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Infraspection Institute Standards



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Infraspection Institute 425 Ellis Street Burlington, NJ 08016 www.infraspection.com



Standard for Infrared Inspection of Building Envelopes



2008 Edition



Infraspection Institute 425 Ellis Street Burlington, NJ 08016 www.infraspection.com



Standard for Infrared Inspection of Building Envelopes Foreword This standard outlines the procedures and documentation requirements for conducting infrared inspections of building envelopes. This standard covers an application which is both art and science. This document assumes that the reader is generally familiar with the science of infrared thermography. It is not intended to be an absolute step-by-step formula for conducting an infrared inspection. The use of this standard is not intended to qualify an individual using it to conduct an infrared inspection, or to analyze the resulting infrared data without formal training prior to its use. This document is intended to support infrared thermographers who have been professionally trained and certified. It must be acknowledged and understood that the misinterpretation of data that can occur without proper training and experience cannot be avoided simply by using this standard. In no event shall Infraspection Institute be liable to anyone for special, collateral, incidental or consequential damages in conjunction with or arising from use of this standard.



Other Infraspection Institute Standards Infraspection Institute began publishing guidelines for infrared thermography in 1988. Since their initial publication, Infraspection Institute guidelines have been adopted by hundreds of companies worldwide and incorporated into documents published by other recognized standards organizations such as the American Society for Testing and Materials (ASTM). Beginning in 2007, Infraspection Institute guidelines were renamed as standards to reflect their industry-wide acceptance and the best practices they embody. Several standards are available from Infraspection Institute. These standards cover equipment operation, temperature measurement, and specific applications. A complete list of current Infraspection Institute standards may be found online at www.infraspection.com. Infraspection Institute standards represent the work of many practicing infrared thermographers and other experts. We thank them for their valuable contributions.



Copyright © 2008, Infraspection Institute 1



Standard for Infrared Inspection of Building Envelopes 2008 Edition



Table of Contents 1.0



Scope



Page 3



2.0



Referenced Documents



Page 3



3.0



Terminology



Page 3



4.0



Significance and Use



Page 4



5.0



Responsibilities of the Infrared Thermographer



Page 5



6.0



Responsibilities of the End User



Page 5



7.0



Instrument Requirements



Page 6



8.0



Limitations (Applicability of Constructions)



Page 6



9.0



Inspection Procedures



Page 6



10.0



Significant Environmental Parameters



Page 9



11.0



Required Conditions



Page 9



12.0



Data Interpretation



Page 10



13.0



Verification



Page 10



14.0



Documentation



Page 10



Copyright © 2008, Infraspection Institute • 425 Ellis Street • Burlington, NJ 08016



This document may be reproduced for personal use and not for profit, without charge, provided you include all of the copyright and address information listed above. Failure to include this information with any reproduction is an infringement of the copyright and is subject to legal action and consequences. Copyright © 2008, Infraspection Institute 2



1.0



Scope



1.1



This standard covers procedures for conducting infrared inspections of building envelopes for the purpose of detecting thermal patterns caused by excess energy loss, latent moisture, or structural details.



1.2



This standard provides a common document for the end user to specify infrared inspections and for the infrared thermographer to perform them.



1.3



This standard lists the joint responsibilities of the end user and the infrared thermographer that, when carried out, will result in the safest and highest-quality inspection for both.



1.4



This standard outlines specific content for documenting the results of an infrared inspection.



1.5



This standard may involve use of equipment in hazardous or remote locations.



1.6



This standard addresses criteria for infrared imaging equipment, such as spatial resolution and thermal sensitivity.



1.7



This standard addresses meteorological conditions under which infrared inspections should be performed.



1.8



This standard addresses operating procedures and operator qualifications.



1.9



This standard addresses verification of infrared data using invasive test methods.



1.10 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.



2.0



Referenced Documents



2.1



Occupational Safety and Health Standards for General Industry 29 CFR, Part 1910. US Department of Labor. Occupational Safety & Health Administration, Washington, DC.



2.2



Occupational Safety and Health Standards for the Construction Industry 29 CFR, Part 1926. US Department of Labor. Occupational Safety & Health Administration, Washington, DC.



2.3



Level-l Certified Infrared Thermographer Reference Manual. Infraspection Institute, Burlington, NJ.



3.0



®



Terminology



For the purpose of this standard, 3.1



Building envelope - those portions of the building that separate conditioned from unconditioned spaces.



3.2



End user - the person requesting infrared thermographic inspections.



3.3



Exception - an abnormally warm or cool portion of a building that may be a potential problem for the end user.



Copyright © 2008, Infraspection Institute 3



3.4



Infrared inspection - the use of infrared imaging equipment to provide specific thermal information and related documentation about a structure, system, object or process.



3.5



Infrared thermal imager (infrared camera) - a camera-like device that detects, displays and records the apparent thermal patterns across a given surface.



3.6



Infrared thermographer - a person who is trained and qualified to use an imaging radiometer.



3.7



Inspection window - the time period during which infrared inspections of building envelopes can be successfully conducted.



3.8



Moisture meter probe - an invasive (electrical resistance or galvanometric type) test that entails the insertion of a meter probe(s) into a material to indicate the presence of moisture.



3.9



Qualified assistant - a person provided and authorized by the end user to perform the tasks required to assist the infrared thermographer. He/she is knowledgeable of the operation and history of the building(s) to be inspected and is trained in all the safety practices and rules of the end user.



3.10 Qualitative infrared thermography - the practice of gathering information about a structure, system, object or process by observing images of different patterns of infrared radiation, and recording and presenting that information. 3.11 Quantitative infrared thermography - the practice of measuring temperatures of the observed patterns of infrared radiation. 3.12 Standard - a set of specifications that define the purposes, scope and content of a procedure. 3.13 Thermogram - a recorded visual image that maps the apparent temperature pattern of an object or scene into a corresponding contrast or color pattern. 3.14 Thermographer - see Infrared thermographer.



4.0 4.1



4.2



Significance and Use The purpose of an infrared inspection of a building envelope is to locate and document abnormal patterns of infrared radiation from the building envelope (exceptions) that can be potential problems for the end user. 4.1.1



Conductive exceptions are usually caused by insufficient, improperly installed, damaged or water-saturated insulation and/or structural components.



4.1.2



Convective exceptions are usually caused by cracks and holes that permit the uncontrolled movement of air across the building envelope.



4.1.3



Destructive testing is necessary to verify the presence of water in the insulation.



Opinions about the causes of these exceptions, the integrity of the building envelope, or recommendations for corrective actions requires skills beyond those of infrared thermography. 4.2.1



Infrared thermography will be presented as a visual inspection technique to gather and present information about the system at a specific time.



4.2.2



Providing destructive testing of any structures for verification of suspected problems is beyond the scope of infrared thermography.



Copyright © 2008, Infraspection Institute 4



4.2.3 4.3



5.0



Data from infrared inspections may be used to assess the condition of a building envelope or for quality assurance inspections of new installations, repairs, or retrofits.



This standard does not provide methods to determine the cause of latent moisture within a building envelope or its point of entry. It does not address the suitability of any particular material or system to function satisfactorily as waterproofing or insulation.



Responsibilities of the Infrared Thermographer



5.1



Infrared inspections will be performed when environmental and physical conditions such as solar gain, wind, surface and atmospheric moisture and heat transfer are favorable to gathering accurate data.



5.2



The thermographer will have knowledge of the materials and construction of building envelopes sufficient to understand the observed patterns of radiation.



5.3



The thermographer will be accompanied by a person who is responsible for the thermographer’s safety.



5.4



Unless so qualified, the thermographer will not perform any tasks that are normally performed by a construction tradesperson.



5.5



The thermographer will comply with the security and safety rules of the end user and applicable safety standards.



5.6



The thermographer will use thermal imaging and/or measurement equipment with capabilities sufficient to meet the inspection requirements.



5.7



When performing quantitative infrared inspections, the thermographer will assure that all temperaturemeasuring equipment meets the manufacturer’s standard specifications for accuracy.



6.0



Responsibilities of the End User



6.1



Prior to the inspection, the end user will inform the thermographer of any past and current problems with the facility to be inspected and the reasons for conducting the inspection.



6.2



Prior to the inspection, the end user will heat or cool the building to be inspected to a uniform air temperature throughout when requested by the thermographer.



6.3



The end user will provide, during the inspection, a qualified assistant familiar with the construction and history of the facility. This person will be responsible for gaining access to, and maintaining the security of, the end user’s facilities and premises. When performing air leakage inspections, this person may need to be qualified to operate and control the building’s HVAC systems.



6.4



For infrared inspections conducted from the inside of the building, it is the end user’s responsibility to remove furniture, wall hangings, and other objects that prevent the thermographer from inspecting the interior wall surfaces prior to the inspection.



6.5



When requested and available, the end user will furnish building drawings and/or blueprints to the thermographer.



6.6



The end user will take full responsibility for consequences resulting from actions taken, or not taken, as a result of information provided by an infrared inspection.



Copyright © 2008, Infraspection Institute 5



7.0 7.1



8.0



Instrument Requirements General 7.1.1



Infrared thermal imaging systems shall detect emitted radiation and convert detected radiation to a real-time visual signal on a monitor screen. Imagery shall be monochrome or multi-color.



7.1.2



Spectral Range: the infrared imaging system shall operate within a spectral range from 2 to 14 µm. A spot radiometer or nonimaging line scanner is not sufficient.



7.1.3



The infrared thermal imaging system shall have a Minimum Resolvable Temperature Difference (MRTD) of 0.1°C or less at 20°C.



Limitations (Applicability of Constructions)



8.1



Applicable constructions include insulated building sidewalls, exterior insulated finish systems (EIFS), and other building finishes which can absorb moisture.



8.2



Certain construction details can preclude the detection of exceptions. Examples include, but are not limited to, stone or brick facades and walls containing dead air spaces.



8.3



Some construction materials can preclude the detection of exceptions. Examples include, but are not limited to, high density materials such as brick, block, stone, spandrel glass, and metal.



8.4



For materials with highly reflective surfaces in the spectral range of the infrared thermal imager, infrared inspections are not practical until the surface is naturally or temporarily dulled.



8.5



The wetting rates of construction materials vary according to the type of material and environmental exposure. Details with insulations that wet slowly, such as EIFS, usually should not be inspected until they are at least three months old.



8.6



Infrared inspections are not intended to identify the source of the moisture.



9.0



Inspection Procedures



9.1



Prior to conducting an infrared inspection, the end user or the qualified assistant will help the thermographer identify the areas to be inspected.



9.2



Prior to the inspection, the thermographer should perform a walk-through of the areas to be inspected with the end user or the qualified assistant.



9.3



9.2.1



In the absence of accurate blueprints or structural drawings, the thermographer will create a graphic representation of the premises showing wall structures and areas included in the inspection.



9.2.1.1



The thermographer should consult any available structural drawings to locate wall voids and other structural areas not readily noticed in a walk-through.



9.2.2



After identifying all the elements of the structure to be inspected, the thermographer should schedule/allow sufficient time for a proper inspection to be made.



Infrared inspections of buildings are generally performed for one or more of the following reasons: to detect excess energy loss, latent moisture, or the location of structural details. Procedures and requirements for these types of inspections are outlined below. Copyright © 2008, Infraspection Institute 6



9.4



Energy Loss 9.4.1



Infrared inspections may be conducted to detect evidence of excess energy loss due to missing, damaged or misapplied insulation or air leakage.



9.4.2



Infrared inspections may be conducted from the exterior and/or the interior of a building; however, inspections performed from the interior are generally more helpful in diagnosing performance issues associated with occupant comfort.



9.4.3



Inspection Procedures



9.4.3.1



With help from the end user or the end user’s representative, the thermographer will define the thermal boundaries of the building envelope.



9.4.3.2



When performing infrared inspections to detect energy loss, the temperature differences across the building envelope will be at least 10C° (18F°) between:



9.4.3.2.1 The conditioned and unconditioned surfaces for at least three hours before performing conduction inspections. 9.4.3.2.2 The building’s inside air temperature and its outside surface temperature when inspecting for air leakage from the outside of a building that is under positive pressure. 9.4.3.2.3 The building’s outside air temperature and its inside surface temperature when inspecting for air leakage from the inside of a building that is under negative pressure. 9.4.3.3



These temperature differences for air leakage inspections may be lowered as higher pressure differences are created across the building envelope.



9.4.3.4



If the building is inspected for air leakage under existing pressure conditions, the thermographer will determine which portions of the building envelope are under positive, negative and neutral pressures.



9.4.3.5



The thermographer may use artificial means of creating uniform pressure differences across the building envelope by using a “blower door” or by asking the qualified assistant to temporarily modify operation of the building’s HVAC system to create the desired pressures.



9.4.3.5.1 The thermographer should be qualified in the safe use and operation of “blower doors” since heating systems and their exhaust gases can be affected by such equipment. 9.4.3.6



Inspections conducted from the exterior of the building should be performed at night or on overcast days to avoid errors due to solar reflections and solar loading. Inspections conducted from the interior of the building may be performed during daytime hours provided that solar loading of exterior walls is not significant.



9.4.3.7



Infrared inspections should be conducted under normal weather conditions with the HVAC system operating normally.



9.4.3.7.1 When inspecting commercial facilities at night, it may be necessary to override the building’s climate controls to duplicate daytime settings. 9.4.3.8



The infrared inspection shall be conducted in an organized fashion to ensure complete coverage of all areas of interest. Items to be inspected shall include walls, windows, and doors. For interior inspections, floors and ceilings should be included as well.



Copyright © 2008, Infraspection Institute 7



9.4.3.9



Exceptions may appear as hot or cold, depending upon the thermographer’s vantage point and weather conditions.



9.4.3.10 Detected exceptions should be documented with a thermogram and daylight photograph. These may be substituted by marking the location and size of exceptions on blueprints or drawings. For large structures, recording thermal imagery to videotape can provide a dynamic record of the infrared inspection. 9.4.3.11 Detected exceptions should be verified by independent means. This may include visual confirmation or the use of invasive testing such as moisture meter probes. 9.5



Latent Moisture 9.5.1



Infrared inspections may be conducted to detect evidence of latent moisture within building materials.



9.5.2



Infrared inspections may be conducted from the exterior and/or the interior of a building. Vantage point should be selected to provide the greatest probability of detection.



9.5.3



Inspection Procedures



9.5.3.1



With help from the end user or the end user’s representative, the thermographer will define the areas to be inspected.



9.5.3.2



Latent moisture generally causes a change in the thermal capacitance and/or thermal conductivity of building materials. Moisture evaporating from a surface will generally cause a pronounced cooling in the wet areas.



9.5.3.3



Infrared inspections to detect latent moisture shall be conducted when conditions are most favorable for gathering accurate data.



9.5.3.4



Inspections conducted from the exterior of the building should be performed post sunset following a sunny day with calm wind conditions. Exceptions associated with latent moisture will generally appear warm.



9.5.3.4.1 Inspections conducted from the interior of the building may be performed during daytime hours provided that solar loading of exterior walls is not significant. Exceptions associated with latent moisture may appear as warm or cold, depending upon environmental conditions.



9.6



9.5.3.5



The infrared inspection shall be conducted in an organized fashion to ensure complete coverage of all areas of interest. Items to be inspected shall include walls, windows, and doors. For interior inspections, floors and ceilings should be included as well.



9.5.3.6



Detected exceptions should be documented with a thermogram and daylight photograph. These may be substituted by marking the location and size of exceptions on blueprints or drawings. For large structures, recording thermal imagery to videotape can provide a dynamic record of the infrared inspection.



9.5.3.7



Detected exceptions should be verified by independent means. This may include visual confirmation or the use of invasive testing such as moisture meter probes.



Structural Details 9.6.1



Infrared inspections may be conducted to detect evidence of structural details within building walls, ceilings, roofs, or floors.



Copyright © 2008, Infraspection Institute 8



10.0



9.6.2



Infrared inspections may be conducted from the exterior or the interior of a building. Vantage point should be selected to provide the greatest probability of detection.



9.6.3



Inspection Procedures



9.6.3.1



With help from the end user or the end user’s representative, the thermographer will define the areas to be inspected.



9.6.3.2



Structural details generally cause a change in the thermal capacitance and/or thermal conductivity of building materials. Examples include, but are not limited to, studs or framing members within framed walls, fasteners in wall systems, and reinforcing grout details in block walls. Under the correct conditions, these details may be thermographically detected.



9.6.3.3



Infrared inspections to detect structural details shall be conducted when conditions are most favorable for gathering accurate data.



9.6.3.4



The infrared inspection shall be conducted in an organized fashion to ensure complete coverage of all areas of interest.



9.6.3.5



Detected exceptions should be documented with a thermogram and daylight photograph. These may be substituted by marking the location and size of exceptions on blueprints or drawings. For large structures, recording thermal imagery to videotape can provide a dynamic record of the infrared inspection.



9.6.3.6



Detected exceptions should be verified by independent means. This may include visual confirmation or the use of invasive testing as appropriate.



Significant Environmental Parameters



10.1 Water retained in building materials such as EIFS decreases the thermal resistance and increases the heat storage capacity of such systems. This can lead to thermal anomalies on the surface that can be located using an infrared thermal imager. These thermal anomalies depend upon the type of material, the amount of moisture in the material, and the weather conditions. For a given building envelope, there are four weather related parameters that can cause significant changes in surface temperatures over wet areas compared to dry areas. These are: inside to outside temperature difference, the rate of change of temperature in the hours prior to viewing, the amount of solar loading, and the wind speed. 10.2 Acceptable weather conditions for nighttime infrared imaging inspections will be calm winds with some combination of a large inside to outside temperature difference, a rapid decrease in ambient temperature in the late afternoon and a sunny day prior to the inspection. Typically, an infrared inspection during cold weather relies on a large inside to outside temperature difference. An infrared inspection during warm weather relies on solar loading.



11.0



Required Conditions



11.1 No appreciable precipitation shall have fallen during the 24 hours prior to the infrared survey. 11.2 At the time of the infrared inspection, all surfaces shall be dry. 11.3 For exterior inspections, winds in the area shall be less than 25 km/h (15 mph) at the time of the inspection.



Copyright © 2008, Infraspection Institute 9



12.0



Data Interpretation



12.1 The interpretation of infrared data is a process of pattern recognition for the purpose of differentiating exceptions from those caused by the following: 12.1.1



Variations in the type, thickness, density, or continuity of insulation.



12.1.2



Variations in wall thickness, moisture content, or continuity.



12.1.3



Variations in the type or thickness of wall surfacing.



12.1.4



Variations within the building walls.



12.1.5



Inconsistencies in walls due to damage, repairs, coatings, or overlays.



12.1.6



Variations in temperature behind walls.



12.1.7



Fasteners, flashings, flanges, or projections from walls or discontinuities within them.



12.1.8



Variations in surface emittance.



12.1.9



Infrared radiation from nearby sources.



12.1.10



Hot or cold air from nearby sources.



12.1.11



Moisture or debris on inspected surfaces.



12.1.12



Variations in shape or geometry of inspected surfaces.



12.2 Accurate interpretation of infrared data requires verification.



13.0



Verification



13.1 In order to determine the cause of exceptions, verification of infrared data must be carried out by the following invasive test methods: visual testing or moisture meter probes. 13.2 Noninvasive testing equipment such as nuclear and capacitance meters may be used to compliment, but not replace invasive verification.



14.0



Documentation



14.1 The thermographer will provide documentation for all infrared inspections. The following information will be included in a written report to the end user: 14.1.1



The name and valid certification level(s) and number(s) of the infrared thermographer.



14.1.2



The name and address of the end user.



14.1.3



The name(s) of the assistant(s) accompanying the infrared thermographer during the inspection.



14.1.4



The manufacturer, model and serial number of the infrared equipment used.



Copyright © 2008, Infraspection Institute 10



14.1.5



A description of the location and construction of the building(s) that were inspected.



14.1.6



When performing air leakage inspections, notations of which parts of the building are under positive, negative or neutral pressures.



14.1.7



The date(s) of the inspection and when the report was prepared.



14.1.8



When performing a qualitative infrared inspection, the thermographer will provide the following information for each exception identified:



14.1.8.1 A description of the exception including its exact location and the direction it faces. 14.1.8.2 The time the exception was documented. 14.1.8.3 The weather conditions surrounding the exception including the inside and outside air temperatures, wind speed and direction, and the sky conditions. 14.1.8.4 Hard copies of a thermal image (thermogram) and corresponding visible-light image of the exception. When approved by the end user, the thermographer may provide sketches or drawings in place of, or in addition to, thermograms and photographs. 14.1.8.5 The field-of-view of the infrared camera lens. 14.1.8.6 Notation of any windows, filters or external optics used. 14.1.8.7 Any other information or special conditions that may affect the results, repeatability or interpretation of the exception. 14.1.9



When performing a quantitative infrared inspection, the thermographer will provide the following additional information for each exception documented:



14.1.9.1 The distance from the infrared camera to the exception. 14.1.9.2 The emissivity, reflected temperature and any transmittance values used to calculate the temperature of the exception. 14.1.9.3 The surface temperature of the exception and of a defined reference, if applicable.



Copyright © 2008, Infraspection Institute 11



Standard for Measuring Distance/Target Size Values for Infrared Imaging Radiometers



2008 Edition



Infraspection Institute 425 Ellis Street Burlington, NJ 08016 www.infraspection.com



Standard for Measuring Distance/Target Size Values for Infrared Imaging Radiometers Foreword This standard outlines the procedures and documentation requirements for measuring distance/target size values for infrared imaging radiometers. This standard covers a technique which is both art and science. This document assumes that the reader is generally familiar with the science of infrared thermography. The use of this standard is not intended to qualify an individual using it to conduct an infrared inspection, or to analyze the resulting infrared data without formal training prior to its use. This document is intended to support infrared thermographers who have been professionally trained and certified. It must be acknowledged and understood that the misinterpretation of data that can occur without proper training and experience cannot be avoided simply by using this standard. In no event shall Infraspection Institute be liable to anyone for special, collateral, incidental or consequential damages in conjunction with or arising from use of this standard.



Other Infraspection Institute Standards Infraspection Institute began publishing guidelines for infrared thermography in 1988. Since their initial publication, Infraspection Institute guidelines have been adopted by hundreds of companies worldwide and incorporated into documents published by other recognized standards organizations such as the American Society for Testing and Materials (ASTM). Beginning in 2007, Infraspection Institute guidelines were renamed as standards to reflect their industry-wide acceptance and the best practices they embody. Several standards are available from Infraspection Institute. These standards cover equipment operation, temperature measurement, and specific applications. A complete list of current Infraspection Institute standards may be found online at www.infraspection.com. Infraspection Institute standards represent the work of many practicing infrared thermographers and other experts. We thank them for their valuable contributions.



Copyright © 2008, Infraspection Institute 1



Standard for Measuring Distance/Target Size Values for Infrared Imaging Radiometers 2008 Edition



Table of Contents 1.0



Scope



Page 3



2.0



Referenced Documents



Page 3



3.0



Terminology



Page 3



4.0



Summary of Test Method



Page 4



5.0



Significance and Use



Page 4



6.0



Equipment Required



Page 4



7.0



Procedure



Page 5



8.0



Calculations



Page 6



9.0



Documentation



Page 7



10.0



Notes



Page 7



Copyright © 2008, Infraspection Institute • 425 Ellis Street • Burlington, NJ 08016



This document may be reproduced for personal use and not for profit, without charge, provided you include all of the copyright and address information listed above. Failure to include this information with any reproduction is an infringement of the copyright and is subject to legal action and consequences. Copyright © 2008, Infraspection Institute 2



1.0



Scope



1.1



The purpose of this standard is to provide infrared thermographers with a practical test method for determining the measurement performance of an infrared imaging radiometer.



1.2



This standard provides a procedure for establishing the Distance/Target Size Value required for producing accurate temperatures with an infrared imaging radiometer. The desired accuracy (percentage of target temperature) may be chosen by the infrared thermographer.



1.3



The Distance/Target Size Value can be used to determine the maximum distance from a target to achieve a desired percentage of measurement accuracy.



1.4



The Distance/Target Size Value can be used to determine the minimum target size required to achieve a desired percentage of measurement accuracy at a given distance from the target.



1.5



This test method may involve use of equipment and materials in the presence of heated equipment.



1.6



This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.



2.0



Referenced Documents



2.1



Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers, Infraspection Institute.



2.2



Standard for Measuring and Compensating for Emissivity Using Infrared Imaging Radiometers, Infraspection Institute.



2.3



Level-II Certified Infrared Thermographer Reference Manual, Infraspection Institute.



3.0



Terminology



3.1



Aperture device - a mechanical device that is opaque to infrared radiation and has an opening through which an infrared imaging radiometer is sighted during testing.



3.2



Blackbody simulator - a device with an emittance close to 1.00 that can be heated or cooled to a known, stable temperature.



3.3



Distance/Target Size Value - a numerical value that may be used to determine the measurement area of an infrared imaging radiometer at a given distance. This value may also be used to calculate minimum target size at a given distance.



3.4



Emittance or emissivity - the ratio of the infrared energy emitted by an object compared to a blackbody at the same wavelength and temperature. Emittance is specified as a number between 0 and 1.



3.5



Infrared imaging radiometer (imaging radiometer) - a thermal imager capable of measuring temperature.



3.6



Infrared thermographer - a person who is trained and qualified to use an imaging radiometer.



3.7



Reflected temperature - is the apparent temperature value reported by a radiometer that corresponds to the infrared energy incident upon, and reflected from the measured surface of an object. Copyright © 2008, Infraspection Institute 3



3.8



Thermal imager - a camera-like device which converts infrared energy emitted by an object into a realtime, visible light image.



3.9



Thermographer - see Infrared thermographer.



4.0



Summary of Test Method



4.1



Three methods are given for determining the Distance/Target Size Value for an infrared imaging radiometer.



4.2



One method is given for determining Distance/Target Size Value using an aperture device with a horizontal opening and an infrared imaging radiometer positioned in a normal upright orientation.



4.3



One method is given for determining Distance/Target Size Value using an aperture device with a vertical opening and an infrared imaging radiometer positioned in a normal upright orientation.



4.4



One method is given for determining Distance/Target Size Value using an aperture device with a circular opening and an infrared imaging radiometer positioned in a normal upright orientation.



4.5



One procedure is given for calculating the measurement area of an infrared imaging radiometer at a given distance.



4.6



One procedure is given for calculating the minimum target size at a given distance when measuring with an infrared imaging radiometer.



5.0 5.1



6.0



Significance and Use This standard encompasses test procedures for determining Distance/Target Size Values for infrared imaging radiometers.



Equipment Required



6.1



A calibrated imaging radiometer with standard measurement functions and a tripod.



6.2



A temperature-controllable blackbody simulator with a surface of a known emittance greater than or equal to 0.97. The blackbody simulator surface should have a minimum width of 7.5 cm and should maintain the desired temperature within +/- 0.5 C° or 1% of the desired temperature, whichever is larger.



6.3



An adjustable aperture device with a maximum width greater than or equal to the width of the blackbody simulator surface. One side of the aperture device should have an emittance of greater than 0.95. The other side should be highly reflective. Should aperture device opening have walls greater than 1 mm thick, walls of opening shall have emittance greater than 0.95.



6.4



A mounting apparatus to hold the aperture device directly in front of the blackbody simulator. The mounting apparatus must allow for quick and easy removal and replacement of the aperture device.



6.5



Calipers with a measurement accuracy of +/- 0.01 mm.



6.6



A distance measuring device with a measurement accuracy of +/- 1.0 mm.



6.7



A test room that can maintain a stable ambient air temperature of 18 to 24°C, +/- 0.5 C°. The room should be free of any intense sources of radiation that might affect the test results. The room should be free of drafts. Copyright © 2008, Infraspection Institute 4



7.0



Procedure



7.1



Prepare the test room by eliminating or shielding any intense sources of thermal radiation from striking the surface of the blackbody simulator or aperture device.



7.2



Record the ambient air temperature, Tamb, at the start of the test and at 30-minute intervals during the test. The air must maintain a stable temperature within the specifications stated in 5.7.



7.3



Set the blackbody simulator to 60°C or to the desired temperature. Wait until it maintains a stable temperature within the specifications stated in 5.2.



7.4



Place the imaging radiometer at the desired location and distance from the object to be measured. The use of a tripod or other support device is recommended.



7.5



Place the imager one meter from the blackbody simulator, positioned so that it views the face of the blackbody simulator at a right angle. Note: This distance may be increased if using a telephoto lens with a minimum focus greater than one meter. Aim and focus the imaging radiometer on the portion of the object where emittance is to be measured.



7.6



Measure and compensate for the object’s reflected temperature. Refer to the Infraspection Institute Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers.



7.7



Enter the known emittance value of the blackbody simulator face in the imager’s computer.



7.8



Focus the imager directly on the face of the blackbody simulator. Using high thermal sensitivity, adjust the imager’s controls to produce a middle-gray image of the surface. Using the imaging radiometer’s appropriate measurement function (i.e. cross-hair, spot or isotherm) measure the temperature of the center of the blackbody simulator surface, (Tbb), with the thermal imager. The imaging radiometer’s reported temperature should be within +/- 1 C° of the temperature indicated by the blackbody simulator’s thermometer. Check equipment for errors if the temperatures are beyond specifications.



7.9



Operate the aperture device so that the opening is one-half the width of the blackbody simulator face width. Place the aperture device directly in front of the blackbody simulator face with the high-emittance surface facing the imaging radiometer (see Figure 1).



Aperture Device



Blackbody Simulator



IR D Figure 1 Copyright © 2008, Infraspection Institute 5



7.10 Focus the imager on the aperture device and place the measurement function at the center of the aperture device. Move the imager away from the aperture until the imager’s reported temperature is less than temperature Tbb, taken in 7.8. Then move the imager closer to the aperture until the reported temperature Tbb is re-established. Be sure to focus the imaging radiometer’s lens at each new position. Measure and record the distance (D) from the imager lens face to the aperture device. Remove the aperture device from its holder when not required for measurement to prevent it from heating up. 7.11 Using the following formulae, calculate the temperature that will be required for each level of accuracy, i.e., 98% (T1), 95% (T2), 90% (T3) and 50% (T4): (Tbb-Tamb) x .98 + Tamb = T1 (Tbb-Tamb) x .95 + Tamb = T2 (Tbb-Tamb) x .90 + Tamb = T3 (Tbb-Tamb) x .50 + Tamb = T4 7.12 With the imager still placed at distance (D) from the aperture, close the aperture device, place it again in front of the simulator face. Slowly increase the width of the aperture until the imager reports temperature T1. 7.13 Remove the aperture device from its holder and use the calipers to measure the aperture opening and note the result. Ensure that the opening is not changed during removal or measurement. 7.14 While the aperture device is removed, re-measure the temperature of the blackbody simulator with the imager to ensure that the reported temperature is within the temperature specifications stated in 6.2. 7.15 Conduct procedures 7.6 through 7.14 a minimum of three times for each desired level of temperature accuracy. Average the results of the tests. 7.16 Conduct procedures 7.6 through 7.15 to determine the aperture widths necessary to produce temperatures T2, T3 and T4.



8.0 8.1



Calculations Calculate and record the Distance/Target Size Value for each of the percentage of temperature test measurements as follows: Value = Distance (mm from lens to target) Aperture Width (mm)



8.2



The Distance/Target Size Value can be used to calculate the minimum target size needed to achieve a desired percentage of accuracy at a specified Distance from the target. Distance is measured from imager lens to target. Minimum Target Size = Distance ÷ Value



8.3



The Distance/Target Size Value can be used to calculate the maximum distance from a target to achieve a desired percentage of measurement accuracy. Distance is measured from imager lens to target. Maximum Distance = Target Size x Value



Copyright © 2008, Infraspection Institute 6



9.0 9.1



Documentation The following information will be included in a written report for the subject radiometer. 9.1.1



Thermal imager manufacturer, model number, serial number, lens field-of-view and the waveband sensed.



9.1.2



Blackbody simulator manufacturer, model number, serial number and the emittance of its surface.



9.1.3



Caliper manufacturer and model number.



9.1.4



Ambient room temperatures noted during the test.



9.1.5



Temperatures of the blackbody simulator noted during the test.



9.1.6



Value for each percentage of temperature calculated and for each differently-shaped aperture tested.



10.0 Notes 10.1 The calculated Values may change when viewing different temperature targets. These procedures may be conducted using blackbody simulators set to different temperatures. Take appropriate safety precautions when working with high-temperature blackbody simulators. 10.2 Differently-shaped apertures may produce different Values. These procedures may be conducted using aperture devices of different shapes, such as circular and rectangular. Following are some representative shapes that may be tested:



Circular



Vertical Slit



Horizontal Slit



Figure 2



10.3 The corresponding Distance/Target Size Value is specific to the temperature of the target measured and the imager and lens used.



Copyright © 2008, Infraspection Institute 7



Standard for Infrared Inspection of Electrical Systems & Rotating Equipment



2008 Edition



Infraspection Institute 425 Ellis Street Burlington, NJ 08016 www.infraspection.com



Standard for Infrared Inspection of Electrical Systems & Rotating Equipment Foreword This standard outlines the procedures and documentation requirements for conducting infrared inspections of electrical systems and rotating equipment. This standard covers an application which is both art and science. This document assumes that the reader is generally familiar with the science of infrared thermography. It is not intended to be an absolute step-by-step formula for conducting an infrared inspection. The use of this standard is not intended to qualify an individual using it to conduct an infrared inspection, or to analyze the resulting infrared data without formal training prior to its use. This document is intended to support infrared thermographers who have been professionally trained and certified. It must be acknowledged and understood that the misinterpretation of data that can occur without proper training and experience cannot be avoided simply by using this standard. In no event shall Infraspection Institute be liable to anyone for special, collateral, incidental or consequential damages in conjunction with or arising from use of this standard.



Other Infraspection Institute Standards Infraspection Institute began publishing guidelines for infrared thermography in 1988. Since their initial publication, Infraspection Institute guidelines have been adopted by hundreds of companies worldwide and incorporated into documents published by other recognized standards organizations such as the American Society for Testing and Materials (ASTM). Beginning in 2007, Infraspection Institute guidelines were renamed as standards to reflect their industry-wide acceptance and the best practices they embody. Several standards are available from Infraspection Institute. These standards cover equipment operation, temperature measurement, and specific applications. A complete list of current Infraspection Institute standards may be found online at www.infraspection.com. Infraspection Institute standards represent the work of many practicing infrared thermographers and other experts. We thank them for their valuable contributions.



Copyright © 2008, Infraspection Institute 1



Standard for Infrared Inspection of Electrical Systems & Rotating Equipment 2008 Edition Table of Contents 1.0



Scope



Page 3



2.0



Referenced Documents



Page 3



3.0



Terminology



Page 4



4.0



Significance and Use



Page 5



5.0



Responsibilities of the Infrared Thermographer



Page 5



6.0



Responsibilities of the End User



Page 6



7.0



Instrument Requirements



Page 6



8.0



Inspection Procedures



Page 7



9.0



Documentation



Page 8



10.0



Delta T Criteria for Electrical Systems



Page 10



11.0



Absolute Temperature Criteria for Electrical Systems



Page 11



12.0



Delta T Criteria for Mechanical Systems



Page 13



13.0



Absolute Temperature Criteria for Mechanical Systems



Page 13



14.0



Documents Referenced by Footnotes



Page 16



Copyright © 2008, Infraspection Institute • 425 Ellis Street • Burlington, NJ 08016



This document may be reproduced for personal use and not for profit, without charge, provided you include all of the copyright and address information listed above. Failure to include this information with any reproduction is an infringement of the copyright and is subject to legal action and consequences. Copyright © 2008, Infraspection Institute 2



1.0



Scope



1.1



This standard covers procedures for conducting infrared inspections of electrical systems and rotating equipment.



1.2



This standard provides a common document for the end user to specify infrared inspections and for the infrared thermographer to perform them.



1.3



This standard lists the joint responsibilities of the end user and the infrared thermographer that, when carried out, will result in the safest and highest quality inspection for both.



1.4



This standard outlines specific content for documenting qualitative and quantitative infrared inspections.



1.5



This standard may involve use of equipment in hazardous or remote locations or in close proximity to energized electrical equipment.



1.6



This standard addresses criteria for infrared imaging equipment, such as spatial resolution and thermal sensitivity.



1.7



This standard addresses meteorological conditions under which infrared inspections should be performed.



1.8



This standard addresses operating procedures and operator qualifications.



1.9



This standard addresses verification of infrared data.



1.10 This standard provides temperature limits for electrical and mechanical components and lubricants. 1.11 This standard provides several means for prioritizing exceptions based on temperature. 1.12 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.



2.0



Referenced Documents



2.1



Standard for Measuring and Compensating for Emittance Using Infrared Imaging Radiometers. Infraspection Institute, 425 Ellis Street, Burlington, NJ 08016.



2.2



Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers. Infraspection Institute, 425 Ellis Street, Burlington, NJ 08016.



2.3



Standard for Measuring and Compensating for Transmittance of an Attenuating Medium Using Infrared Imaging Radiometers. Infraspection Institute, 425 Ellis Street, Burlington, NJ 08016.



2.4



NFPA 70B Recommended Practice for Electrical Equipment Maintenance. National Fire Protection Association, 1 Batterymarch Park, Quincy, MA 02169.



2.5



NFPA 70E Standard for Electrical Safety in the Workplace. National Fire Protection Association, 1 Batterymarch Park, Quincy, MA 02169.



2.6



Occupational Safety and Health Standards for General Industry 29 CFR, Part 1910. US Department of Labor. Occupational Safety & Health Administration, Washington, DC.



Copyright © 2008, Infraspection Institute 3



2.7



Occupational Safety and Health Standards for the Construction Industry 29 CFR, Part 1926. US Department of Labor. Occupational Safety & Health Administration, Washington, DC.



2.8



Level-l Certified Infrared Thermographer Reference Manual. Infraspection Institute, Burlington, NJ.



2.9



Level-ll Certified Infrared Thermographer Reference Manual. Infraspection Institute, Burlington, NJ.



3.0



®



®



Terminology



For the purpose of this standard, 3.1



End user - the person requesting an infrared thermographic inspection.



3.2



Exception - an abnormally warm or cool connector, conductor or component that may be a potential problem for the end user.



3.3



Infrared imaging radiometer (imaging radiometer) - a thermal imager capable of measuring temperature.



3.4



Infrared inspection - the use of infrared imaging equipment to provide specific thermal information and related documentation about a structure, system, object or process.



3.5



Infrared thermal imager (infrared camera) - a camera-like device that detects, displays and records the apparent thermal patterns across a given surface.



3.6



Infrared thermographer - a person who is trained and qualified to use an imaging radiometer.



3.7



Non-imaging radiometer (infrared thermometer) - an instrument that measures the average apparent surface temperature of an object based upon the object’s radiance.



3.8



Qualified assistant - a person provided and authorized by the end user to perform the tasks required to assist the infrared thermographer. He/she is knowledgeable of the operation and history of equipment to be inspected and is trained in all the safety practices and rules of the end user.



3.9



Qualitative infrared thermography - the practice of gathering information about a structure, system, object or process by observing images of infrared radiation, and recording and presenting that information.



3.10 Quantitative infrared thermography - the practice of measuring temperatures of the observed patterns of infrared radiation. 3.11 Rotating equipment - Stationary machinery or electro-mechanical devices that have rotating components. 3.12 Standard - a set of specifications that define the purposes, scope and content of a procedure. 3.13 Thermal imager - see Infrared thermal imager. 3.14 Thermogram - a recorded visual image that maps the apparent temperature pattern of an object or scene into a corresponding contrast or color pattern. 3.15 Thermographer - see Infrared thermographer.



Copyright © 2008, Infraspection Institute 4



4.0 4.1



4.2



5.0



Significance and Use The purpose of an infrared inspection is to identify and document exceptions in the end user’s electrical system and/or rotating equipment. 4.1.1



In electrical systems, exceptions are usually caused by loose or deteriorated connections, short circuits, overloads, load imbalances or faulty, mismatched or improperly-installed components.



4.1.2



For rotating equipment, exceptions are usually caused by friction due to improper lubrication, misalignment, worn components or mechanical loading anomalies.



Providing opinions about the causes of exceptions, the integrity of the system, or recommendations for corrective actions requires knowledge and skills beyond those of infrared thermography. 4.2.1



Infrared thermography will be presented as an inspection technique to gather and present information about the system at a specific time.



4.2.2



Infrared thermography will not be promoted as a remedial measure.



4.2.3



An infrared inspection of an electrical system or rotating equipment does not assure proper operation of such equipment. Other tests and proper maintenance are necessary to assure their reliable performance.



Responsibilities of the Infrared Thermographer



5.1



Infrared inspections will be performed when environmental and physical conditions such as solar gain, wind, surface and atmospheric moisture and heat transfer are favorable to gathering accurate data.



5.2



The infrared thermographer will have sufficient knowledge of the components, construction and theory of electrical systems and/or rotating equipment to understand the observed patterns of radiation.



5.3



The infrared thermographer will use thermal imaging and/or measurement equipment with capabilities sufficient to meet the inspection requirements.



5.4



The infrared thermographer will be accompanied by a qualified assistant who is knowledgeable of the equipment being inspected.



5.5



Unless he/she is a licensed electrician, professional engineer, or has other equivalent qualifications, the infrared thermographer will not perform any tasks that are normally done by these personnel. Unless so qualified and authorized by the end user, the infrared thermographer: 5.5.1



Will not remove or replace covers or open or close cabinets containing electrical equipment.



5.5.2



Will not measure electric loads of the equipment.



5.5.3



Will not touch any inspected equipment and will maintain a safe distance from such equipment.



5.5.4



Will comply with the safety practices and rules of the end user and applicable safety standards.



5.6



When performing quantitative infrared inspections, the infrared thermographer will assure that all temperature-measuring equipment meets the manufacturers’ standard specifications for accuracy.



5.7



After repair, and when requested by the end user, the thermographer will reinspect each exception to assure that the problem has been corrected. Copyright © 2008, Infraspection Institute 5



6.0 Responsibilities of the End User 6.1



The end user will provide or help develop an inventory list of the equipment to be inspected in a logical and efficient route through the facility.



6.2



The end user will provide a qualified assistant(s) who is knowledgeable of the operation and history of the equipment to be inspected. This person(s) will accompany the infrared thermographer during the infrared inspection and, unless specified otherwise, will be qualified and authorized by the end user to: 6.2.1



Obtain authorization necessary to gain access to the equipment to be inspected and will notify operations personnel of the inspection activities.



6.2.2



Open and/or remove all necessary covers immediately before inspection by the infrared thermographer.



6.2.3



Close and/or replace these cabinet and enclosure covers immediately after inspection by the infrared thermographer.



6.2.4



Assure that the equipment to be inspected is under adequate load, create satisfactory loads when necessary, and allow sufficient time for recently-energized equipment to produce stable thermal patterns.



6.2.5



Measure electric loads when requested by the infrared thermographer.



6.3



The end user takes full responsibility for consequences resulting from actions taken, or not taken, as a result of information provided by an infrared inspection.



6.4



After repair, the end user will authorize reinspection of each exception to assure that the problem has been corrected.



7.0 7.1



Instrument Requirements General 7.1.1



Infrared thermal imaging systems shall detect emitted radiation and convert detected radiation to a real-time visual signal on a monitor screen. Imagery shall be monochrome or multi-color.



7.1.2



Spectral Range: the infrared imaging system shall operate within a spectral range from 2 to 14 µm. A spot radiometer or nonimaging line scanner is not sufficient.



7.1.3



The infrared thermal imaging system shall have a Minimum Resolvable Temperature Difference (MRTD) of 0.3°C or less at 20°C.



7.1.4



Infrared equipment may be man portable or vehicle mounted.



7.1.4.1



For vehicle mounted equipment, care should be taken to ensure that equipment is mounted securely, will not interfere with the safe operation of the vehicle, and meets all applicable regulatory requirements.



Copyright © 2008, Infraspection Institute 6



8.0



Inspection Procedures



8.1



Equipment to be inspected shall be energized and under adequate load; ideally this is normal operating load. For acceptance testing, higher loads may be warranted.



8.2



Subject equipment shall be externally examined before opening or removing any protective covers to determine the possible presence of unsafe conditions. If abnormal heating and/or unsafe conditions are found, the end user or qualified assistant shall take appropriate remedial action prior to commencing the infrared inspection.



8.3



Electrical and mechanical equipment enclosures shall be opened to provide line-of-sight access to components contained therein. In some cases, further disassembly may be required to allow for a complete infrared inspection. Examples include dielectric barriers, clear plastic guards, and other materials that are opaque to infrared energy.



8.4



In some cases, the infrared inspection may be conducted through permanently installed view ports or infrared transparent windows. Care must be taken to ensure that all subject equipment can be adequately and completely imaged. In some cases, special lenses may be required for the thermal imager.



8.5



Infrared inspections may be qualitative or quantitative in nature. Qualitative thermographic inspections may be conducted using a thermal imager or an imaging radiometer. Quantitative inspections may be conducted using an imaging radiometer or a thermal imager in combination with a non-imaging radiometer. 8.5.1



When performing qualitative inspections, the thermographer shall utilize a thermal imager with resolution sufficient to provide clear imagery of the inspected components.



8.5.2



When performing quantitative inspections, the thermographer shall utilize an imaging radiometer with resolution sufficient to provide clear imagery and accurate temperature measurement of the inspected components.



8.5.2.1



When performing a quantitative inspection, the thermographer shall make every effort to ensure the accuracy of non-contact temperature measurements. In particular, consideration should be given to target emittance, reflected temperature, weather conditions, and target size.



8.6



Using inventory lists provided by the end user, the thermographer shall inspect electrical components and/or rotating equipment utilizing a thermal imager or imaging radiometer. Inspection shall be conducted in a manner so as to ensure complete coverage of all components.



8.7



Whenever possible, similar components under similar load shall be compared to each other. Components exhibiting unusual thermal patterns or operating temperatures shall be deemed as exceptions and documented with a thermogram and visible light image. 8.7.1



Thermal images shall be stored on electronic media or videotape. Every effort shall be made to ensure the thermal image is in sharp focus.



8.7.2



Visible light images may be recorded with a daylight camera integral to the infrared imager or with a separate daylight or video camera.



8.7.2.1



Visible light images shall be properly exposed to ensure adequate detail. Particular attention should be given to perspective, focus, contrast, resolution, and lighting. Visible light images should align with the thermal image as closely as possible.



Copyright © 2008, Infraspection Institute 7



8.7.3 8.8



In certain cases, one may elect to capture thermograms and visible light images for all inspected components. This practice may be useful for providing quality assurance information or baseline data; however, it can be time and labor intensive for large inventories. 8.8.1



8.9



Thermograms and visible light images shall be included in a written report along with the information required in section 9.



When capturing imagery for all inspected components, thermal and visible light images shall be included in a written report along with the information required in section 9.



As an option, the criteria listed in sections 10 and 11 may be used to help prioritize repair actions; however, use of these criteria is not an exact science and involves risking an unplanned failure. For best results, it is recommended that each exception be inspected for cause and appropriate corrective action taken as soon as possible.



8.10 In some cases, imaging from a motor vehicle or aircraft can provide greater mobility, a superior vantage point, and allow for rapid inspection of large or remote areas. 8.10.1



9.0 9.1



9.2



When imaging from a motor vehicle or aircraft, precautions should be taken to ensure safe operation of the vehicle and imaging equipment, as well as the safety of all occupants.



Documentation The thermographer will provide documentation for all infrared inspections. The following information will be included in a written report to the end user: 9.1.1



The name and any valid certification level(s) and number(s) of the infrared thermographer.



9.1.2



The name and address of the end user.



9.1.3



The name(s) of the assistant(s) accompanying the infrared thermographer during the inspection.



9.1.4



The manufacturer, model and serial number of the infrared equipment used.



9.1.5



A list of all the equipment inspected and notations of the equipment not inspected on the inventory list.



9.1.6



The date(s) of the inspection and when the report was prepared.



When performing a qualitative infrared inspection, the infrared thermographer will provide the following information for each exception identified: 9.2.1



The exact location of the exception.



9.2.2



A description of the exception such as its significant nameplate data, phase or circuit number, rated voltage, amperage rating and/or rotation speed.



9.2.3



When significant, the environmental conditions surrounding the exception including the air temperature, wind speed and direction, and the sky conditions.



9.2.4



Hardcopies of a thermal image (thermogram) and corresponding visible-light image of the exception.



9.2.5



The field-of-view of the infrared imager lens. Copyright © 2008, Infraspection Institute 8



9.3



9.2.6



Notation of any windows, filters or external optics used.



9.2.7



If desired, a subjective evaluation rating provided by the qualified assistant and/or end user representative, of the importance of the exception to the safe and continuous operation of the system.



9.2.8



Any other information or special conditions that may affect the results, repeatability or interpretation of the exception.



When performing a quantitative infrared inspection, the infrared thermographer will provide the following additional information for each exception documented: 9.3.1



The distance from the infrared imager to the exception.



9.3.2



Whenever possible, the maximum rated load of the exception and its measured load at the time of the inspection.



9.3.2.1



The percentage load on the exception, calculated by dividing its measured load by the rated load.



9.3.3



The emittance, reflected temperature and transmittance values used to calculate the temperature of the exception.



9.3.4



When using Delta T criteria, the surface temperature of the exception and of a defined reference and their temperature difference.



9.3.5



When using absolute temperature criteria, the surface temperature of the exception and the standard and the standard temperature(s) referenced.



9.3.6



If desired, an evaluation of the temperature severity of the exception.



9.3.7



If desired, a repair priority rating for the exception based on its subjective rating, temperature severity rating or an average of both.



Copyright © 2008, Infraspection Institute 9



10.0



Delta T Criteria for Electrical Systems



10.1 The infrared thermographer may use the following Delta T (temperature difference) criteria to evaluate the temperature severity of an exception. These Delta T criteria are reported as the temperature rise of the exception above the temperature of a defined reference, which is typically the ambient air temperature, a similar component under the same conditions or the maximum allowable temperature of the component: 1



NETA Maintenance Testing Specifications, for electrical equipment



Priority



Delta T between similar components under similar load



Delta T over ambient air temperature



Recommended Action



4



1 to 3C°



1C° to 10C°



Possible deficiency; warrants investigation



3



4 to 15C°



11C° to 20C°



2



–––



21C° to 40C°



1



>15C°



>40C°



Indicates probable deficiency; repair as time permits Monitor until corrective measures can be accomplished Major discrepancy; repair immediately



2



Military Standard, for electrical equipment Priority



Delta T



Recommended Action



4



10 to 25C°



Component failure unlikely but corrective measure required at next scheduled routine maintenance period or as scheduling permits



3



25 to 40C°



Component failure probable unless corrected



2



40 to 70C°



Component failure almost certain unless corrected



1



70C° and above



Component failure imminent. Stop survey. Inform cognizant officers



3



Experience-Based, for electrical and/or mechanical equipment. Any Delta T classification system 3 based on experience, such as the following Priority



Delta T



Recommended Action



4



1 to 10C°



3



>10 to 20C°



Corrective measures required as scheduling permits



2



>20 to 40C°



Corrective measures required ASAP



1



>40C°



Corrective measures should be taken at the next maintenance period



Corrective measures required immediately



4



Motor Cores, (on test bench, not in service) Priority



Delta T



Recommended Action



3



1 to 10C°



2



>10 to 20C°



1



>20C°



No exception likely Possible exception, consult motor core test data Exception likely Copyright © 2008, Infraspection Institute 10



11.0



Absolute Temperature Criteria for Electrical Systems



11.1 The infrared thermographer may use absolute temperature criteria based on the following ANSI, IEEE and NEMA or other standards to identify electrical system exceptions. 11.2 All temperatures of the following standards are specified in Celsius as follows: Ambient / Rated Rise / Maximum Allowable Note:



Ambient = rated ambient temperature Rated Ambient + Rated Rise = Maximum Allowable Temperature



11.3 When the exception is heating several adjacent components, the lowest temperature component specification should be used. Example: You are inspecting a heating terminal that connects an insulated conductor to a circuit breaker. The component with the lowest temperature specification should be used. 11.4 When several different temperatures for similar equipment are given in the referenced standards, the lowest temperatures (most conservative) are listed. If an exception temperature exceeds the listed maximum allowable temperature limit, it could be operating at a temperature lower than a higher (less conservative) specification. Consult the referenced standard(s). 11.5 When the infrared thermographer is unable to determine the class of insulation or equipment being inspected, he/she should use the lowest temperature (most conservative) specification within the component grouping. Example: You are inspecting an insulated wire that has no visible markings. Use the lowest temperature specification for any conductor insulation. 11.6 Unless noted otherwise, these absolute temperature criteria are based on equipment operating at the 5 stated ambient temperature and at 100% of their rated load. The following formula can be applied to these absolute temperature criteria to give a corrected maximum allowable temperature (Tmaxcorr) for the reduced operating load and actual ambient temperature of the exception: Tmaxcorr



=



{(Ameas ÷ Arated)2 (Trated rise)} + Tambmeas



Tmaxcorr



=



corrected maximum allowable temperature



Ameas



=



measured load, in amperes



Arated



=



rated load, in amperes



Trated rise



=



rated temperature rise (from standard)



Tambmeas



=



measured ambient temperature



Example: A fuse is found to be operating at a temperature of 68°C. The measured ambient temperature (Tambmeas) = 35°C. The fuse is rated at 100 amps (Arated) but its actual load is measured at only 50 amps (Ameas). 1. 2.



What is the Tmaxcorr for the fuse? Is the temperature of the fuse an exception? Tmaxcorr



=



{(Ameas ÷ Arated)2 (Trated rise)} + Tambmeas



Tmaxcorr



= = = = =



{(50 ÷ 100)2 (30)} + 35 {(.5)2 (30)} + 35 {(.25)(30)} + 35



Tmaxcorr



7.5 + 35 42.5°C



The actual operating temperature of the fuse (68°C) is greater than the Tmaxcorr of 42.5°C. This is an exception! Copyright © 2008, Infraspection Institute 11



11.7 Absolute Temperature Criteria: Ambient / Rated Rise / Maximum Conductors (lowest temperature criteria) 6



Bare conductors , in free air Bare conductors, in enclosure Bare conductors, enclosure surface



55/25/80 40/30/70 40/20/60



7



Insulated conductors , in free air Insulated conductors, in enclosure Insulated conductors, enclosure surface Insulated conductors, in sun Conductor Insulations



30/30/60 30/30/60 30/20/50 50/10/60



7



T, TW, R, RW, RU THW, Polyethylene, XHHW, RH-RW Varnished Cambric Paper Lead Varnished Polyester THH, Cross Linked Polyethylene, Ethylene-Propylene Silicone Rubber



30/30/60 30/45/75 30/47/77 30/50/80 30/55/85 30/60/90 30/95/125



Connectors and Terminations (lowest temperature criteria) 10



Metals , silver or silver alloy Metals, copper, copper alloy or aluminum Metals, aluminum alloy Overcurrent Devices



8,9



40/40/80 40/50/90 52/53/105



(lowest temperature criteria)



Circuit breakers, molded case Circuit breakers, all others Fuses



40/20/60 40/30/70 40/30/70



Disconnects and Switches Including Insulators and Supports (lowest temperature criteria) Bushings



11



10



40/30/70



(lowest temperature criteria)



Transformer, lower end Circuit breaker, lower end External terminal Coils and Relays



40/55/95 40/40/80 40/30/70



8,12



Class 90 Class 105 Class 130 Class 155 Class 180 Class 220



40/50/90 40/65/105 40/90/130 40/115/155 40/140/180 40/180/220 13



AC Motors, Field Windings 1.00 SF, class A 1.00 SF, class B 1.00 SF, class F 1.00 SF, class H



40/60/100 40/80/120 40/105/145 40/125/165



1.15 SF, class B 1.15 SF, class F



40/90/130 40/115/155



Note: Casing temperatures may be lower than these specified windings temperatures. Copyright © 2008, Infraspection Institute 12



DC Motors and Generators, Windings



13



1.00 SF, class A 1.00 SF, class B 1.00 SF, class F 1.00 SF, class H



40/70/110 40/100/140 40/130/170 40/155/195



1.25 SF, (2hr), class B 1.25 SF, (2hr), class F



40/80/120 40/110/150



Note: Casing temperatures may be lower than these specified windings temperatures. Cylindrical Rotor Synchronous Generators, Air Cooled, Casing



13



Class B Class F Class H



40/70/110 40/90/130 40/110/150



Transformers, Distribution and Power



14,15,16



Dry type, class 105, windings Dry type, class 150, windings Dry type, class 185, windings Dry type, class 220, windings



30/55/85 30/80/110 30/115/145 30/150/180



Oil cooled, 55°C rise, casing Oil cooled, 65°C rise, casing Note:



12.0



30/55/85 30/65/95



1. Oil-cooled casing temperatures measured near top of liquid in main tank. 2. Most 55C° rise transformers built before 1962. 3. For specialty transformers (other than power and distribution) or other liquid-cooled equipment, such as specified on the nameplate.



Delta T Criteria for Mechanical Systems



12.1 The infrared Thermographer may use Delta T (temperature difference) criteria to rate the temperature severity of mechanical system exceptions. These Delta T criteria are usually reported as the temperature rise of the exception above the temperature of a defined reference. Use the Delta T criteria listed in section 10.1. 12.2 By taking multiple measurements over time of similar components under similar operating and environmental conditions, statistical analysis can be used to set operational limits for trending and predicting the temperature performance of these components.



13.0



Absolute Temperature Criteria for Mechanical Systems



13.1 The infrared thermographer may use absolute maximum allowable temperature criteria based on published standards to identify mechanical system exceptions. 13.2 When an exception is heating several adjacent system components, the component having the lowest temperature specification should be referenced. Example: You are inspecting a bearing of a motor. The applicable adjacent system components are the seals and the lubricant. The component (bearing, seals or lubricant) having the lowest temperature specification should be referenced. Note: In most cases, the lubricant will have the lowest temperature specification. Copyright © 2008, Infraspection Institute 13



13.3 When unable to determine the type of bearing, lubricant or seal, the infrared thermographer should use the lowest component temperature specification within the applicable group. Example: You are inspecting a bearing. You identify the bearing and lubricant types and temperature limits, but you do not know the type of seal. From the list, select the lowest applicable temperature specification for any seal. Compare your measured bearing temperature to the lowest of the three component temperatures (the bearing, lubricant and seal). 13.4 The infrared thermographer often cannot directly measure the surfaces of the components in these specification lists. Care and good judgment must be used when applying these specifications to actual field temperature measurements. 13.5 Unless noted, temperature specifications are based on equipment operating at 100% of their rated load/speed. All temperatures are in Celsius. 13.6 Maximum Allowable Temperature Criteria: Bearings, Rolling Element Types



17



Races (for metallurgical stability) Rolling elements Plastic retainer (cage) Steel retainer (cage) Brass retainer (cage) Steel shield (closure) Nitrile rubber lip seal Acrylic lip seal Silicone lip seal Fluoric lip seal PTFE lip seal Felt seal Aluminum labyrinth seal Bearings, Plain Types Material



125 125 120 300 300 300 100 130 180 180 220 100 300



18



Tin base babbitt Lead base babbitt Cadmium base Copper lead Tin bronze Lead bronze Aluminum



149 149 260 177 260 232 121 19



Bearings, Plain Types, Factory Produced Rulon, filled PTFE Graphite bronze DU PTFE lined fiberglass Nylon Polyurethane Polyacetyl Wood Metalized graphite Pure carbon Polyolefin, UHMPW



204 204 288 177 149 82 104 71 593 399 82 Copyright © 2008, Infraspection Institute 14



Delrin Zytel Teflon Rubber



149 107 288 49 20



Lubricants



(when used with polyamide plastic bearing retainer)



Mineral oils without EP additives, i.e., machine oils, hydraulic fluid EP oils, i.e., industrial, automotive, gearbox oils EP oils, i.e., rear axle, differential, hypoid gear oils



120 110 100



Synthetic oils Polyglycols, poly-olefins Diesters, silicones Phosphate diesters Greases (mineral oil lubricant), lithium, polyurea, bentonite, calcium complex



120 110 100 120



Lubricants, Greases (mineral oil), when used with steel or brass bearing retainer Lithium base Lithium complex Sodium base Sodium complex Calcium (lime) base Calcium complex Barium complex Aluminum complex Inorganic thickeners Polyurea



110 140 80 140 60 130 130 110 130 140



Lubricants, Solid lubricant materials Graphite Molybdenum disulfide Tungsten disulfide Polytetrafluoroethylene



427 450 510 300 21,22



Seals and Gaskets, elastomers O-rings and gaskets Butyl rubber Hypalon Epichlorohydrin rubber Ethylene acrylic EPDM Fluorocarbon (viton, kalrez) Fluorosilicone Neoprene Nitrile Polyacrylate rubber Polysulfide rubber Polyurethane Silicone rubber



107 121 135 177 149 204 177 149 135 177 107 93 232



Copyright © 2008, Infraspection Institute 15



Lip Seals Nitrile Polyacrylate rubber Silicone rubber Fluorocarbon (viton, kalrez) Leather



121 149 163 204 93



23



Mechanical Seal Material , (see above for elastomers) Stellite Tungsten carbide Stainless steel Ni-resist Bronze, leaded Ceramic Carbon Silicon carbide Glass-filled teflon



177 232 316 177 177 177 275 1,650 177 24



Power Transmission Components



V-belts Chain drives: limited by maximum lube temperature. Gear drives: limited by maximum lube temperature.



14.0



60



Documents Referenced by Footnotes



1.



Maintenance Testing Specifications for Electric Power Distribution Equipment and Systems. International Electric Testing Association, 2700 W. Centre Ave., Suite A, Portage, Michigan 49024



2.



Infrared Thermal Imaging Survey Procedure for Electrical Equipment ML-STD-2194 (SH). Naval Publications and Printing Service, 700 Robbins Ave., Bldg. 4D, Philadelphia, Pennsylvania 19111



3.



Level-II Certified Infrared Thermographer Reference Manual. Infraspection Institute, 425 Ellis Street, Burlington, New Jersey 08016



4.



Infrared Inspection of Motor Cores, by Michael Dreher, 1992. Available from Infraspection Institute



5.



ANSI/IEEE C37.010-4.4.3. IEEE Application Guide for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis



6.



ANSI/IEEE C37.20.1-1987 Standard for Metal-Enclosed Low-Voltage Power Circuit Breaker Switchgear ANSI/IEEE C37.20.2-1987 Standard for Metal-Clad and Station-Type Cubicle Switchgear ANSI/IEEE C37.20.3-1987 Standard for Metal-Enclosed Interrupter Switchgear



7.



ANSI/IEEE Standard 242-1986, IEEE Recommended Practice for Protection and Coordination of Industrial and Commercial Power Systems



8.



NEMA AB-1, Molded Case Circuit Breakers



9.



ANSI/IEEE C37.40-1981, Service Conditions and Definitions for High-Voltage Fuses, Distribution Enclosed Single-Pole Air Switches, Fuse Disconnecting Switches and Accessories



10.



ANSI/IEEE Standard C37.30-1971, Definitions and Requirements for High-Voltage Air Switches, Insulators and Supports Copyright © 2008, Infraspection Institute 16



11.



IEEE C37-1991, Guides and Standards for Circuit Breakers, Switchgear, Relays, Substations and Fuses



12.



ANSI/IEEE C37.63-1984 Standard Requirement for Overhead, Pad-Mounted, Dry-Vault, and Submersible Automatic Line Sectionalizers for AC Systems



13.



NEMA MG1-1987, Motor and Generators



14.



ANSI/IEEE Standard 141-1986, Power Switching, Transformation, and Motor-Control Apparatus



15.



ANSI/IEEE C57.94-1982 IEEE Recommended Practice for Installation, Application, Operation and Maintenance of Dry-Type General Purpose Distribution and Power Transformers



16.



ANSI/IEEE C57.92-1981 IEEE Guide for Loading Mineral-Oil-Immersed Power Transformers Up to and Including 100MVA with 55° and 65° Average Winding Rise



17.



SKF General Catalogue 4000 US, 1991, SKF



18.



Machinery’s Handbook, 22nd Edition, Industrial Press



19.



The Plane Bearing Handbook, 1989, Bearings Inc



20.



Steyr Bearings Technical Manual 281E, 1981, Steyr



21.



Parker O-Ring Handbook, Parker Seals



22.



CR Handbook of Seals, CR Industries



23.



Duraseal Manual, Durametallic



24.



Eaton Power Transmission Catalogue, Eaton



Copyright © 2008, Infraspection Institute 17



Standard for Measuring and Compensating for Emittance Using Infrared Imaging Radiometers



2008 Edition



Infraspection Institute 425 Ellis Street Burlington, NJ 08016 www.infraspection.com



Standard for Measuring and Compensating for Emittance Using Infrared Imaging Radiometers Foreword This standard outlines the procedures and documentation requirements for measuring and compensating for emittance using an infrared imaging radiometer. This standard covers a technique which is both art and science. This document assumes that the reader is generally familiar with the science of infrared thermography. The use of this standard is not intended to qualify an individual using it to conduct an infrared inspection, or to analyze the resulting infrared data without formal training prior to its use. This document is intended to support infrared thermographers who have been professionally trained and certified. It must be acknowledged and understood that the misinterpretation of data that can occur without proper training and experience cannot be avoided simply by using this standard. In no event shall Infraspection Institute be liable to anyone for special, collateral, incidental or consequential damages in conjunction with or arising from use of this standard.



Other Infraspection Institute Standards Infraspection Institute began publishing guidelines for infrared thermography in 1988. Since their initial publication, Infraspection Institute guidelines have been adopted by hundreds of companies worldwide and incorporated into documents published by other recognized standards organizations such as the American Society for Testing and Materials (ASTM). Beginning in 2007, Infraspection Institute guidelines were renamed as standards to reflect their industry-wide acceptance and the best practices they embody. Several standards are available from Infraspection Institute. These standards cover equipment operation, temperature measurement, and specific applications. A complete list of current Infraspection Institute standards may be found online at www.infraspection.com. Infraspection Institute standards represent the work of many practicing infrared thermographers and other experts. We thank them for their valuable contributions.



Copyright © 2008, Infraspection Institute 1



Standard for Measuring and Compensating for Emittance Using Infrared Imaging Radiometers 2008 Edition



Table of Contents 1.0



Scope



Page 3



2.0



Referenced Documents



Page 3



3.0



Terminology



Page 3



4.0



Summary of Test Method



Page 3



5.0



Significance and Use



Page 4



6.0



Precautions and Error Sources



Page 4



7.0



How to Measure the Emittance of an Object



Page 5



8.0



How to Compensate for the Emittance of an Object



Page 6



Copyright © 2008, Infraspection Institute • 425 Ellis Street • Burlington, NJ 08016



This document may be reproduced for personal use and not for profit, without charge, provided you include all of the copyright and address information listed above. Failure to include this information with any reproduction is an infringement of the copyright and is subject to legal action and consequences.



Copyright © 2008, Infraspection Institute 2



1.0



Scope



1.1



This test method covers procedures for measuring and compensating for emittance when measuring the surface temperature of an object with an imaging radiometer.



1.2



This test method may involve use of equipment and materials in the presence of heated or electrically energized equipment, or both.



1.3



This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.



2.0



Referenced Documents



2.1



Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers. Infraspection Institute, Burlington, NJ.



2.2



Level-ll Certified Infrared Thermographer Reference Manual. Infraspection Institute, Burlington, NJ.



3.0



®



Terminology



3.1



Contact radiometer - an infrared thermometer designed for contact temperature measurements. Contact radiometers are usually constructed with a mirrored cavity around their lens.



3.2



Emittance or emissivity - the ratio of the infrared energy emitted by an object compared to a blackbody at the same wavelength and temperature. Emittance is specified as a number between 0 and 1.



3.3



Infrared imaging radiometer (imaging radiometer) - a thermal imager capable of measuring temperature.



3.4



Infrared thermographer - a person who is trained and qualified to use an imaging radiometer.



3.5



Non-imaging radiometer - an instrument that measures the average apparent surface temperature of an object based upon the object’s radiance.



3.6



Reflected temperature - the apparent temperature value reported by a radiometer that corresponds to the infrared energy incident upon, and reflected from the measured surface of an object.



3.7



Surface-modifying material - any tape, spray, or paint that is used to change the emittance of an object.



3.8



Thermographer - see Infrared thermographer.



4.0



Summary of Test Methods



4.1



Two methods are given for measuring the emittance of an object: Contact Method and Non-Contact Method.



4.2



A procedure is also given for compensating for errors due to object emittance by using the computer built into an imaging radiometer.



Copyright © 2008, Infraspection Institute 3



5.0



Significance and Use



5.1



The emittance of an object can cause significant error when measuring temperature with an imaging radiometer. Two methods are provided for measuring emittance.



5.2



These methods can be used in the field or laboratory using commonly available materials.



5.3



These methods may also be used with non-imaging radiometers that have the required computer capabilities.



6.0 6.1



Precautions and Error Sources Contact Method 6.1.1



6.2



Contact thermometers can act as heat sinks and change the temperature of an object.



Non-Contact Method 6.2.1



The use of surface-modifying materials can change the heat transfer properties and temperature of an object. Such errors can be minimized by applying surface-modifying materials to the smallest area that satisfies the measurement accuracy requirements of the imaging radiometer.



6.2.2



Prior to applying surface-modifying material to an object as directed in 7.3.3, make certain that area to be modified and adjacent area are at the same temperature.



6.2.3



When removing a surface-modifying material as directed in 7.3.6, errors can be minimized by ensuring that the surface is returned to its original condition.



6.3



Both Contact and Non-Contact test methods require the object temperature be at least 10°C warmer or cooler than the ambient temperature. Potential errors can be minimized by ensuring the stability of the temperature difference between the object and the ambient temperature during the test. Additionally, the accuracy of the emittance measurement can be increased by increasing this temperature difference.



6.4



The emittance of an object may be specific to the temperature of the object and the spectral waveband of the imaging radiometer used. Therefore, the temperature of the object and the spectral waveband of the imaging radiometer should be noted along with the measured emittance value.



6.5



These methods are valid only for objects that are opaque in the waveband of the imaging radiometer utilized.



6.6



Some imaging radiometers do not have inputs for reflected temperature. Emittance values determined with such instruments may be exaggerated. The amount of exaggeration will depend upon the emittance of the object and the amount of infrared energy reflected from it.



6.7



As the emittance of an object decreases, its reflectivity increases. Careful consideration and avoidance of potential error sources, including the precise determination of reflected temperature, is required to accurately determine the emittance value of an object. For materials with emittance values of less than 0.5, emittance measurements and radiometric temperature measurements have a high likelihood of error.



6.8



Both methods of measuring emittance require contact with the target surface. Do not touch any energized or potentially dangerous surfaces unless you are qualified to do so and have taken the necessary safety precautions.



Copyright © 2008, Infraspection Institute 4



7.0 7.1



7.2



7.3



How to Measure the Emittance of an Object Equipment Required 7.1.1



A calibrated imaging radiometer with a computer that allows the infrared thermographer to input reflected temperature (R) and emittance (E) values.



7.1.2



A natural or induced means of heating or cooling the target at least 10C (18F) above or below ambient temperature. The target temperature should be stable and close to the temperature of the target(s) you will be measuring in the field.



7.1.3



The Contact Method requires a calibrated contact thermometer such as a thermocouple and thermocouple reader or a contact radiometer.



7.1.4



The Non-Contact Method requires a surface-modifying material such as paint or tape with a known high emittance in the waveband of the subject imaging radiometer.



Contact Method 7.2.1



Place the imaging radiometer at the desired location and distance from the object to be measured. The use of a tripod or other support device is recommended. Aim and focus the imaging radiometer on the portion of the object where emittance is to be measured.



7.2.2



Measure and compensate for the object’s reflected temperature. Refer to the Infraspection Institute Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers.



7.2.3



With the imaging radiometer’s emittance control set to 1.00, use an appropriate imager measurement function, such as spot temperature, cross hairs, or isotherms to define a measurement point or area where emittance is to be measured.



7.2.4



Use a contact thermometer or contact radiometer to measure the temperature of the point or area just defined by the imaging radiometer’s measurement function. Record this temperature.



7.2.5



Without moving the imaging radiometer, adjust its emittance control until the indicated temperature matches the temperature recorded in 7.2.4. The indicated emittance value is the measured emittance value of this object at this temperature and waveband.



7.2.6



Conduct procedures 7.2.1 through 7.2.5 a minimum of three times to obtain an average emittance value.



Non-Contact Method 7.3.1



Place the imaging radiometer at the desired location and distance from the object to be measured. The use of a tripod or other support device is recommended. Aim and focus the imaging radiometer on the portion of the object where emittance is to be measured.



7.3.2



Measure and compensate for the object’s reflected temperature. Refer to the Infraspection Institute Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers.



7.3.3



Apply a surface-modifying material on, or immediately adjacent to, the area of the object where emittance is to be measured. Make sure the surface-modifying material is dry and in good contact with the object. Allow sufficient time for modifying-material to achieve thermal equilibrium with object. Copyright © 2008, Infraspection Institute 5



8.0



7.3.4



Enter the known emittance value of the surface-modifying material into the imaging radiometer under the E input (commonly referred to as “E,” “Emissivity” or “Emittance”).



7.3.5



Use the imaging radiometer to measure the temperature of the surface-modifying material. Record this temperature.



7.3.6



Use the imaging radiometer to measure the temperature of the area immediately adjacent to the surface-modifying material.



7.3.6.1



As an alternative, remove the surface-modifying material and use the imaging radiometer to measure the temperature of the previously modified surface. When removing the surfacemodifying material, be sure to completely remove material and any residue, and allow enough time for the object’s temperature to stabilize.



7.3.7



Without moving the imaging radiometer, adjust its E control until the radiometer indicates the same temperature recorded in 7.3.5. The indicated emittance value is the measured emittance value of this object at this temperature and waveband.



7.3.8



Conduct procedures 7.3.1 through 7.3.7 a minimum of three times to obtain an average emittance value.



How to Compensate for the Emittance of an Object



8.1



Determine object emittance utilizing either Contact Method described in 7.2 or Non-Contact Method described in 7.3.



8.2



Compensate for object emittance by entering the average emittance value of the object in the imaging radiometer under the E input (commonly referred to as “E,” “Emissivity” or “Emittance”).



Copyright © 2008, Infraspection Institute 6



Standard for Infrared Inspections to Detect Pests and Pest Related Damage



2008 Edition



Infraspection Institute 425 Ellis Street Burlington, NJ 08016 www.infraspection.com



Standard for Infrared Inspections to Detect Pests and Pest Related Damage Foreword This standard outlines the procedures and documentation requirements for conducting infrared inspections to detect pests and pest related damage. This standard covers an application which is both art and science. This document assumes that the reader is generally familiar with the science of infrared thermography. It is not intended to be an absolute step-by-step formula for conducting an infrared inspection. The use of this standard is not intended to qualify an individual using it to conduct an infrared inspection, or to analyze the resulting infrared data without formal training prior to its use. This document is intended to support infrared thermographers who have been professionally trained and certified. It must be acknowledged and understood that the misinterpretation of data that can occur without proper training and experience cannot be avoided simply by using this standard. In no event shall Infraspection Institute be liable to anyone for special, collateral, incidental or consequential damages in conjunction with or arising from use of this standard.



Other Infraspection Institute Standards Infraspection Institute began publishing guidelines for infrared thermography in 1988. Since their initial publication, Infraspection Institute guidelines have been adopted by hundreds of companies worldwide and incorporated into documents published by other recognized standards organizations such as the American Society for Testing and Materials (ASTM). Beginning in 2007, Infraspection Institute guidelines were renamed as standards to reflect their industry-wide acceptance and the best practices they embody. Several standards are available from Infraspection Institute. These standards cover equipment operation, temperature measurement, and specific applications. A complete list of current Infraspection Institute standards may be found online at www.infraspection.com. Infraspection Institute standards represent the work of many practicing infrared thermographers and other experts. We thank them for their valuable contributions.



Copyright © 2008, Infraspection Institute 1



Standard for Infrared Inspections to Detect Pests and Pest Related Damage 2008 Edition



Table of Contents 1.0



Scope



Page 3



2.0



Referenced Documents



Page 3



3.0



Terminology



Page 3



4.0



Significance and Use



Page 4



5.0



Responsibilities of the Infrared Thermographer



Page 5



6.0



Responsibilities of the End User



Page 5



7.0



Equipment Requirements



Page 5



8.0



Inspection Procedures



Page 6



9.0



Data Interpretation



Page 8



10.0



Verification



Page 9



11.0



Documentation



Page 10



Copyright © 2008, Infraspection Institute • 425 Ellis Street • Burlington, NJ 08016



This document may be reproduced for personal use and not for profit, without charge, provided you include all of the copyright and address information listed above. Failure to include this information with any reproduction is an infringement of the copyright and is subject to legal action and consequences. Copyright © 2008, Infraspection Institute 2



1.0



Scope



1.1



This standard covers procedures for conducting an infrared inspection to locate and document patterns of infrared radiation associated with pest presence or pest related damage.



1.2



This standard provides a common document for the end user to specify infrared inspections and for the infrared thermographer to perform them.



1.3



This standard lists the joint responsibilities of the end user and the infrared thermographer that, when carried out, will result in the safest and highest quality inspection for both.



1.4



This standard outlines specific content for documenting the results of an infrared inspection.



1.5



This standard may involve use of equipment in hazardous or remote locations or in close proximity to animals or insects.



1.6



This standard addresses criteria for infrared imaging equipment, such as spatial resolution and thermal sensitivity.



1.7



This standard addresses meteorological conditions under which infrared inspections should be performed.



1.8



This standard addresses operating procedures and operator qualifications.



1.9



This standard addresses verification of infrared data using invasive test methods.



1.10 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.



2.0



Referenced Documents



2.1



Standard for Infrared Inspection of Insulated Roofs. Infraspection Institute, Burlington, NJ.



2.2



Standard for Infrared Inspection of Building Envelopes. Infraspection Institute, Burlington, NJ.



3.0



Terminology



For the purpose of this standard, 3.1



Critter - a living creature.



3.2



Critter Control Professional - a person who is Licensed and/or Certified to perform animal control and/or removal by the State(s) or region(s) in which they operate.



3.3



Delta-T - refers to the temperature differential between two objects.



3.4



End user - the person requesting an infrared inspection.



3.5



Exception - an abnormally warm or cool portion of a building or structure that may be indicative of pest presence or pest damage.



3.6



Infrared inspection - the use of infrared imaging equipment to provide specific thermal information and related documentation about a structure, system, object, or process. Copyright © 2008, Infraspection Institute 3



3.7



Infrared thermographer - a person who performs and documents an infrared inspection.



3.8



Integrated Pest Management Professional - a person who is Licensed and/or Certified to perform pest inspections by the State(s) or region(s) in which they operate.



3.9



Pest - an animal, critter, insect, or organism whose presence is unwanted.



3.10 Pest damage - the resulting destruction of property or structure or the construction of unwanted nests or structures by pests. 3.11 Qualitative infrared thermography - the practice of gathering information about a structure, system, object, or process by observing images of different patterns of infrared radiation, and recording and presenting that information. 3.12 Standard - a set of specifications that define the purposes, scope, and content of a procedure. 3.13 Thermal imager - a camera-like device which converts infrared energy emitted by an object into a realtime, visible light image. 3.14 Thermogram - a recorded visual image that maps the apparent temperature pattern of an object or scene into a corresponding contrast or color pattern. 3.15 Thermographer - see Infrared thermographer. 3.16 Wood destroying organism - an insect or fungus that damages structures by feeding on, or nesting in, construction materials made of wood.



4.0 4.1



4.2



Significance and Use The purpose of an infrared inspection is to locate and document patterns of infrared radiation associated with pest presence or pest related damage. In some cases, pests and pest damage may be detected directly by thermal imaging. In other cases, evidence of pests and pest damage may be detected indirectly by observing thermal patterns across the surface of structures. 4.1.1



Conductive exceptions are thermal anomalies that may be the result of past or present or pest activity. For structures, conductive exceptions may also be caused by missing or damaged insulation; structural components; and/or water-saturated insulation that may be attractive to or supportive of pests.



4.1.2



Convective exceptions are usually caused by cracks and holes that permit the uncontrolled movement of air across, through, or within a structure. Convective exceptions may provide clues to pest entry points within a given structure.



Providing opinions about the causes of thermal patterns, exceptions, the integrity of structures, or recommendations for corrective actions, pest management and/or critter control requires skills beyond those of infrared thermography. 4.2.1



Infrared thermography will be presented as an inspection technique to gather and present thermal information at a specific time.



4.2.2



Providing destructive testing of any structures for verification of suspected problems is beyond the scope of infrared thermography.



4.2.3



An infrared inspection of a structure that detects no exceptions does not assure that the subject structure is free of pests or pest related damage. Copyright © 2008, Infraspection Institute 4



5.0



Responsibilities of the Infrared Thermographer



5.1



Infrared inspections will be performed when environmental and physical conditions such as solar gain, wind, surface and atmospheric moisture and heat transfer are favorable to gathering accurate data.



5.2



The infrared thermographer will have knowledge of the materials and construction of building envelopes and/or structures sufficient to understand the observed patterns of radiation. The infrared thermographer will also have knowledge of the biology, morphology, and habits of the anticipated pest(s). When performing infrared inspections to indirectly detect pests or pest damage, the infrared thermographer shall also be qualified as a licensed or certified Integrated Pest Management or Critter Control Professional.



5.3



The infrared thermographer will be accompanied by a person who is responsible for the infrared thermographer’s safety when accessing crawl spaces, attics, roofs, limited access areas, or confined spaces.



5.4



Unless so qualified, the infrared thermographer will not perform any tasks that are normally performed by an Integrated Pest Management or Critter Control Professional or other tradesperson.



5.5



The infrared thermographer will comply with the security and safety rules of the end user.



5.6



The infrared thermographer will use thermal imaging and/or other measurement or inspection equipment with capabilities sufficient to meet the inspection requirements.



6.0



Responsibilities of the End User



6.1



Prior to the inspection, the end user will inform the infrared thermographer of any past and current pest problems with the facility or areas to be inspected and the reasons for conducting the inspection.



6.2



Prior to inspections of buildings, the end user will heat or cool the building to be inspected to a uniform air temperature throughout when requested by the infrared thermographer.



6.3



During the inspection, the end user will provide a qualified assistant familiar with the construction and history of the facility. This person will be responsible for gaining access to, and maintaining the security of, the end user’s facilities and premises. If performing air leakage inspections to locate potential pest entry points, this person may need to be qualified to operate and control the building’s HVAC systems.



6.4



When performing inspections from the inside of a building, it is the end user’s responsibility to remove furniture, wall hangings and other objects that prevent the infrared thermographer from inspecting the interior wall surfaces.



6.5



When requested and available, the end user will furnish building drawings and/or blueprints to the infrared thermographer.



6.6



The end user will take full responsibility for consequences resulting from actions taken, or not taken, as a result of information provided by an infrared inspection.



7.0 7.1



Instrument Requirements General 7.1.1



Infrared thermal imaging systems shall detect emitted radiation and convert detected radiation to a real-time visual signal on a monitor screen. Imagery shall be monochrome or multi-color.



Copyright © 2008, Infraspection Institute 5



8.0



7.1.2



Spectral Range: the infrared imaging system shall operate within a spectral range from 2 to 14 µm. A spot radiometer or nonimaging line scanner is not sufficient.



7.1.3



The infrared thermal imaging system shall have a Minimum Resolvable Temperature Difference (MRTD) of 0.1°C or less at 20°C.



7.1.4



Infrared equipment may be man portable or vehicle mounted.



7.1.4.1



For vehicle mounted equipment, care should be taken to ensure that equipment is mounted securely, will not interfere with the safe operation of the vehicle, and meets all applicable regulatory requirements.



Inspection Procedures



8.1



Prior to conducting an infrared inspection, the end user or the qualified assistant will help the thermographer identify the areas to be inspected..



8.2



Prior to inspecting a building, the thermographer should perform a walk-through of the areas to be inspected with the end user or the qualified assistant.



8.3



8.2.1



In the absence of accurate blueprints or structural drawings, the thermographer will create a graphic representation of the premises showing wall structures and areas included in the inspection.



8.2.1.1



The thermographer should consult any available structural drawings to locate wall voids and other structural areas not readily noticed in a walk-through.



8.2.2



After identifying all the elements of the structure to be inspected, the thermographer should schedule/allow sufficient time for a proper inspection to be made.



Direct Detection 8.3.1



Certain pests may be directly detected with a thermal imager. These pests are typically warm-blooded animals such as rodents, fowl, bats, deer, or marsupials. In some cases, coldblooded organisms may be directly detected due to heat associated with their presence; examples include, but are not limited to: bees, wasps and hornets.



8.3.2



In order to detect pests directly, a direct line-of-sight is required between the imager and the subject pest.



8.3.2.1



Line-of-sight must be free of any obstructions, including glass or plastic.



8.3.3



The ability to directly detect pests is influenced by an interdependent set of circumstances, including, but not limited to: size of pest, distance to pest, surface temperature of pest, environmental conditions, and spatial resolution and thermal sensitivity of the thermal imager utilized.



8.3.3.1



Prior to imaging, the infrared thermographer should select imaging equipment sufficient to detect subject pest(s). For large pests such as deer, direct detection may be possible at considerable distances.



8.3.4



Prior to imaging, consideration should be given to pest behavior and habits, time of day, and environmental conditions to ensure that imaging is conducted when subject pest is likely to be present. Imaging should be performed in a manner sufficiently covert to prevent the infrared thermographer from scaring subject pests away from area(s) being imaged or provoking pests into attacking. Copyright © 2008, Infraspection Institute 6



8.4



8.3.5



In some cases, imaging from a motor vehicle or aircraft can provide greater mobility, a superior vantage point, and allow for rapid inspection of large areas.



8.3.5.1



When imaging from a motor vehicle or aircraft, precautions should be taken to ensure safe operation of the vehicle and imaging equipment, as well as the safety of all occupants.



8.3.6



Visual confirmation of subject pest may be required unless pest morphology or behavior are adequate for identification.



8.3.6.1



False positives may be encountered when imaging in wooded areas, populated areas, or rough terrain. False positives may be caused by domestic animals, rocks, or other structures.



8.3.7



When performing infrared inspections for animal counts such as deer, care should be taken to avoid double counting subject animals.



8.3.7.1



For animal counts, multiple inspections over a period of time may be necessary for accurate statistical analysis.



8.3.8



An infrared inspection is valid only for the time and date that the inspection is performed.



8.3.8.1



Negative findings do not ensure that pests have not been or will not be present at other times.



Indirect Detection 8.4.1



Evidence of pest presence or pest damage may be indirectly detected with a thermal imager. Examples include rodents nesting within walls or structures; or the presence of insect activity sufficient to cause a detectable temperature differential such as a beehive within a wall cavity or other structural area.



8.4.1.1



Evidence of conditions attractive to pests such as latent moisture may also be detected with a thermal imager. Detection of such conditions may or may not be associated with past or present pest activity or conditions conducive to mold or microbial growth.



8.4.2



In order to detect pests or pest damage indirectly, a direct line-of-sight is required between the imager and the surface of the area being imaged.



8.4.2.1



Line-of-sight must be free of any obstructions, including glass or plastic.



8.4.3



The ability to indirectly detect pests or pest damage is influenced by an interdependent set of circumstances including, but not limited to: size of thermal pattern; distance to subject surface; emittance, thermal conductivity and temperature of subject surface; environmental conditions; and spatial resolution and thermal sensitivity of the thermal imager utilized.



8.4.3.1



Prior to imaging, the infrared thermographer should select imaging equipment sufficient to detect anticipated thermal patterns associated with subject pest(s) or pest damage.



8.4.4



Prior to imaging, consideration should be given to thermal patterns associated with subject pest(s) and/or pest damage. In particular, consideration should be given to time of day, structural characteristics such as emittance and environmental conditions to ensure that imaging is conducted under optimal conditions. Imaging should be performed in a manner sufficiently covert to prevent the infrared thermographer from scaring subject pests away from area(s) being imaged or provoking pests into attacking.



8.4.4.1



In order to indirectly detect pests or pest damage, a detectable temperature differential must be present across the imaged surface. In the absence of a detectable Delta-T, one may be created by actively heating or cooling the subject areas by one of the following methods: Copyright © 2008, Infraspection Institute 7



8.4.4.1.1 Active heating of subject surface. A quartz light or hot air gun may be used to create a necessary Delta-T for small areas; for large structures, inspections may be performed during evening hours following a sunny day. 8.4.4.1.2 Active cooling of subject surface. Compressed air or other non-hazardous gases may be temporarily injected into subject structures to create a necessary Delta-T.



9.0 9.1



8.4.4.2



When employing active heating or cooling techniques, care should be taken to avoid damaging subject structure or creating safety or fire hazards.



8.4.5



For infrared inspections of building sidewalls, ceilings, and floors, an alternate for achieving a desired temperature differential is to conduct the infrared inspection when there is a Delta-T of at least 10 C° (18 F°) across the building envelope between:



8.4.5.1



The conditioned and unconditioned surfaces for at least three hours before performing conduction inspections.



8.4.5.2



The building’s inside air temperature and its outside surface temperature when inspecting for air leakage from the outside of a building that is under positive pressure.



8.4.5.3



The building’s outside air temperature and its inside surface temperature when inspecting for air leakage from the inside of a building that is under negative pressure.



8.4.6



Temperature differences for air leakage inspections may be lowered as higher pressure differences are created across a building envelope.



8.4.7



If a building is inspected for air leakage under existing pressure conditions, the infrared thermographer will determine which portions of the building envelope are under positive, negative and neutral pressures.



8.4.8



If inspecting a building for air leakage, the infrared thermographer may use artificial means of creating uniform pressure differences across the building envelope by using a “blower door” or by asking the qualified assistant to temporarily modify operation of the building’s HVAC system to create the desired pressures.



8.4.8.1



The infrared thermographer should be qualified in the safe use and operation of “blower doors” since heating systems and their exhaust gases can be affected by such equipment. If not so qualified, the infrared thermographer should work with another person who is.



8.4.9



An infrared inspection is valid only for the time and date that the inspection is performed.



8.4.9.1



Negative findings do not ensure that pests have not been or will not be present at other times.



Data Interpretation Exceptions associated with pests or pest damage may show as inexplicably warm or cold areas. Temperature of exceptions will be determined by an interdependent set of circumstances including, but not limited to: presence or absence of pest; type of damage; environmental conditions; imaging vantage point; and the use of active heating/cooling techniques. 9.1.1



Warm exceptions are usually caused by:



9.1.1.1



The presence of warm blooded pests or sizeable insect infestation.



9.1.1.2



Pest damage to building insulation when heat flow through damaged areas is toward imager. Copyright © 2008, Infraspection Institute 8



9.2



10.0



9.1.1.3



Pest damage when inspecting under active heating conditions.



9.1.2



Cold exceptions are usually caused by:



9.1.2.1



Latent moisture within materials or structural components.



9.1.2.2



Pest damage to building insulation when heat flow through damaged areas is away from imager.



9.1.2.3



Pest damage when inspecting under active cooling conditions.



Exceptions associated with latent moisture are typically amorphously shaped or may follow the geometric shape associated with wet materials. Depending upon conditions, exceptions may appear hot or cold. 9.2.1



Cold exceptions caused by latent moisture are generally caused by evaporation of moisture from the wet areas. These types of exceptions are commonly associated with wet carpet, furniture, or drywall.



9.2.2



Warm exceptions associated with latent moisture are possible due to increased thermal conductivity through wet materials or when materials are being actively wetted by a hot liquid. An example of the latter would be a hot water leak occurring behind drywall.



Verification



10.1 All infrared data must be verified by independent means. 10.1.1



False positives and false negatives may be caused by construction details; structural characteristics; missing or damaged insulation; or air movement within wall cavities of structures.



10.1.2



The infrared thermographer should employ the appropriate verification equipment/tools for each inspection. The infrared thermographer should be certified and/or skilled in the use of such equipment. Verification equipment should include the following as appropriate:



10.1.2.1 Visual Inspection 10.1.2.2 Moisture Meter(s) 10.1.2.3 Digital Camera 10.1.2.4 Video Camera 10.1.2.5 Boroscope 10.1.2.6 Acoustic Emissions Detector 10.1.2.7 Microwave Movement Detector 10.1.2.8 CO2 Detector 10.2 Materials found to be wet should be tested for mold presence or other microbial growth as appropriate.



Copyright © 2008, Infraspection Institute 9



11.0



Documentation



11.1 The infrared thermographer will provide documentation for all infrared inspections. The following information will be included in a written report to the end user: 11.1.1



The name and valid certification level(s) and number(s) of the infrared thermographer.



11.1.2



The name and address of the end user.



11.1.3



The name(s) of the assistant(s) accompanying the infrared thermographer during the inspection.



11.1.4



The manufacturer, model and serial number of the infrared equipment used.



11.1.5



The address and a description of the location and construction of the facilities that were inspected and notations of any portions that could not be inspected.



11.1.6



When performing air leakage inspections, notations of which parts of a building are under positive, negative or neutral pressures.



11.1.7



The date(s) of the inspection and when the report was prepared.



11.1.8



A list of all other test equipment utilized in the inspection, including make, model and serial number for each piece of equipment.



11.2 The infrared thermographer will provide the following information for each exception identified: 11.2.1



A description of each exception including its exact location and the direction it faces.



11.2.2



The time the exception was documented.



11.2.3



The weather conditions surrounding the exception including the inside and outside air temperatures, wind speed and direction, and the sky conditions.



11.2.4



Hard copies of a thermal image (thermogram) and corresponding visible-light image of the exception.



11.2.5



The field-of-view of the infrared camera lens.



11.2.6



Notation of any windows, filters or external optics used.



11.2.7



Any other information or special conditions that may affect the results, repeatability, or interpretation of the data.



11.2.8



Results of tests performed with other inspection equipment to confirm infrared data.



11.2.9



As an option, thermal data may be recorded to videotape or movie file in order to provide a permanent historical record of the inspection.



Copyright © 2008, Infraspection Institute 10



Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers



2008 Edition



Infraspection Institute 425 Ellis Street Burlington, NJ 08016 www.infraspection.com



Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers Foreword This standard outlines the procedures and documentation requirements for measuring and compensating for reflected temperature using an infrared imaging radiometer. This standard covers a technique which is both art and science. This document assumes that the reader is generally familiar with the science of infrared thermography. The use of this standard is not intended to qualify an individual using it to conduct an infrared inspection, or to analyze the resulting infrared data without formal training prior to its use. This document is intended to support infrared thermographers who have been professionally trained and certified. It must be acknowledged and understood that the misinterpretation of data that can occur without proper training and experience cannot be avoided simply by using this standard. In no event shall Infraspection Institute be liable to anyone for special, collateral, incidental or consequential damages in conjunction with or arising from use of this standard.



Other Infraspection Institute Standards Infraspection Institute began publishing guidelines for infrared thermography in 1988. Since their initial publication, Infraspection Institute guidelines have been adopted by hundreds of companies worldwide and incorporated into documents published by other recognized standards organizations such as the American Society for Testing and Materials (ASTM). Beginning in 2007, Infraspection Institute guidelines were renamed as standards to reflect their industry-wide acceptance and the best practices they embody. Several standards are available from Infraspection Institute. These standards cover equipment operation, temperature measurement, and specific applications. A complete list of current Infraspection Institute standards may be found online at www.infraspection.com. Infraspection Institute standards represent the work of many practicing infrared thermographers and other experts. We thank them for their valuable contributions.



Copyright © 2008, Infraspection Institute 1



Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers 2008 Edition



Table of Contents 1.0



Scope



Page 3



2.0



Referenced Documents



Page 3



3.0



Terminology



Page 3



4.0



Summary of Test Methods



Page 3



5.0



Significance and Use



Page 4



6.0



Precautions and Error Sources



Page 4



7.0



How to Measure Reflected Temperature



Page 4



8.0



How to Compensate for Reflected Temperature



Page 6



Copyright © 2008, Infraspection Institute • 425 Ellis Street • Burlington, NJ 08016



This document may be reproduced for personal use and not for profit, without charge, provided you include all of the copyright and address information listed above. Failure to include this information with any reproduction is an infringement of the copyright and is subject to legal action and consequences.



Copyright © 2008, Infraspection Institute 2



1.0



Scope



1.1



This test method covers procedures for measuring and compensating for reflected temperature when measuring the surface temperature of an object with an imaging radiometer.



1.2



This test method may involve use of equipment and materials in the presence of heated or electrically energized equipment, or both.



1.3



This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.



2.0 2.1



3.0



Referenced Documents ®



Level-ll Certified Infrared Thermographer Reference Manual. Infraspection Institute, Burlington, NJ.



Terminology



3.1



Diffuse reflector - a surface that produces a diffuse image of a reflected source.



3.2



Emittance or emissivity - the ratio of the infrared energy emitted by an object compared to a blackbody at the same wavelength and temperature. Emittance is specified as a number between 0 and 1.



3.3



Infrared imaging radiometer (imaging radiometer) - a thermal imager capable of measuring temperature.



3.4



Infrared reflector - a material with a reflectance as close as possible to 1.00.



3.5



Infrared thermographer - a person who is trained and qualified to use an imaging radiometer.



3.6



Infrared thermometer - see Non-imaging radiometer.



3.7



Non-imaging radiometer - an instrument that measures the average apparent surface temperature of an object based upon the object’s radiance.



3.8



Reflected temperature - the apparent temperature value reported by a radiometer that corresponds to the infrared energy incident upon, and reflected from the measured surface of an object.



3.9



Specular reflector - a surface that produces a direct image of a reflected source.



3.10 Thermal imager - a camera-like device which converts infrared energy emitted by an object into a realtime, visible light image. 3.11 Thermographer - see Infrared thermographer.



4.0



Summary of Test Methods



4.1



Two methods are given for measuring the reflected temperature of an object: the Reflector Method and the Direct Method.



4.2



A procedure is also given for compensating for the error produced by reflected temperature using the computer built into an imaging radiometer.



Copyright © 2008, Infraspection Institute 3



5.0



Significance and Use



5.1



The reflectivity of an object can cause significant error when measuring temperature with an imaging radiometer. Two methods are provided for measuring reflected temperature.



5.2



These methods can be used in the field or laboratory using commonly available materials.



5.3



These methods may also be used with non-imaging radiometers that have the required computer capabilities.



6.0 6.1



6.2



Precautions and Error Sources Reflector Method 6.1.1



This method uses an infrared reflector with an assumed reflectance of 1.0, which is an ideal property. Errors can be minimized by using a reflector having a reflectance as close as possible to 1.0.



6.1.2



Objects vary in that they can be diffuse or spectral reflectors, or both. Use of an infrared reflector with reflectance properties as close as possible to those of the object will reduce errors.



Direct Method 6.2.1



The Direct Method usually does not account for heat from the infrared thermographer’s body as a source of reflected temperature. In some cases, this omission can create a significant error. To minimize this error, the thermographer should use the reflector method whenever possible.



6.3



The measured reflected temperature of an object is specific to the imaging radiometer utilized.



6.4



The measured reflected temperature is specific to individual objects at the time of measurement. Reflected temperature should be recalculated whenever reflected sources or environmental conditions change significantly.



6.5



The significance of error due to reflected temperature can be estimated by shielding the object from various angles and observing any changes in the thermal image.



6.6



The error caused by reflected temperature can be reduced by shielding the object from the source of the reflection.



6.7



Reflected temperature errors produced by a point source such as the sun are difficult to measure accurately. These error sources can often be avoided by moving the imaging radiometer’s position and angle relative to the object.



6.8



Reflected temperature can be lower than ambient temperature.



7.0 7.1



How to Measure Reflected Temperature Equipment Required 7.1.1



A calibrated imaging radiometer with a computer that allows the infrared thermographer to input reflected temperature (R) and emittance (E) values.



Copyright © 2008, Infraspection Institute 4



7.1.2



7.2



An infrared reflector made from a piece of metal whose reflectance is as close as possible to 1.00. Examples are a crumpled and reflattened piece of aluminum foil placed shiny side up on a piece of cardboard, or a flat piece of metal with diffuse or spectral reflective characteristics similar to those of the object being measured.



Reflector Method 7.2.1



Set the imaging radiometer’s emittance control to 1.00.



7.2.2



Place the imaging radiometer at the desired location and distance from the object to be measured. The use of a tripod or other support device is recommended. Aim and focus the imaging radiometer on the portion of the object where temperature is to be measured.



7.2.3



Place the reflector in the field of view of the imaging radiometer. The reflector must be placed in front of, and in the same plane as the object’s surface (see Figure 1). Maintain a safe working distance from any energized or potentially dangerous objects.



Reflection Source Reflector Parallel to Target



IR Figure 1



7.3



7.2.4



Without moving the imaging radiometer, use an appropriate measurement function, such as spot temperature, cross hairs, or isotherms to measure the apparent surface temperature of the reflector. Imager should be clearly focused on reflector during this measurement. This is the reflected temperature (R) of the target when viewed from the position indicated in 7.2.2.



7.2.5



Conduct procedures 7.2.1 through 7.2.4 a minimum of three times to obtain an average reflected temperature value.



Direct Method 7.3.1



Set the imaging radiometer’s emittance control to 1.00.



7.3.2



Place the imaging radiometer at the desired location and distance from the object to be measured. The use of a tripod or other support device is recommended. Aim and focus the imaging radiometer on the portion of the object where temperature is to be measured. Estimate the angle of reflection and the angle of incidence when viewing the object with the imaging radiometer from this location (see Figure 2).



Reflection Source Line A



Perpendicular to target



A B



IR A = Angle of reflection B = Angle of incidence Angle A = Angle B



Figure 2



Copyright © 2008, Infraspection Institute 5



Target



7.3.3



Position the imaging radiometer so that it is pointing away from the object and in the same direction as the angle of reflection (see Figure 3, line A). Maintain a safe working distance from any energized or potentially dangerous objects.



Reflection Source (Line A) Perpendicular to target A B



IR Target



A = Angle of reflection B = Angle of incidence Angle A = Angle B



Figure 3



8.0



7.3.4



Measure the apparent temperature of objects within the imaging radiometer’s field of view. Use a measurement feature such as area averaging to obtain an average apparent temperature of objects within the imaging radiometer’s field of view. Imager should be clearly focused during this measurement. This is the reflected temperature (R) of the target when viewed from the position indicated in 7.3.2.



7.3.5



Conduct procedures 7.3.1 through 7.3.4 a minimum of three times to obtain an average reflected temperature value.



How to Compensate for Reflected Temperature



8.1



Determine reflected temperature by utilizing either Reflector Method described in 7.2 or Direct Method described in 7.3.



8.2



Compensate for reflected temperature by entering the average reflected temperature value of the object in the imaging radiometer under the R input (commonly referred to as “TAM,” “Amb Temp”, “Reflected Background” or “T Reflected”).



Copyright © 2008, Infraspection Institute 6



Standard for Infrared Inspection of Insulated Roofs



2008 Edition



Infraspection Institute 425 Ellis Street Burlington, NJ 08016 www.infraspection.com



Standard for Infrared Inspection of Insulated Roofs Foreword This standard outlines the procedures and documentation requirements for conducting infrared inspections of insulated roofs. This standard covers an application which is both art and science. This document assumes that the reader is generally familiar with the science of infrared thermography. It is not intended to be an absolute step-by-step formula for conducting an infrared inspection. The use of this standard is not intended to qualify an individual using it to conduct an infrared inspection, or to analyze the resulting infrared data without formal training prior to its use. This document is intended to support infrared thermographers who have been professionally trained and certified. It must be acknowledged and understood that the misinterpretation of data that can occur without proper training and experience cannot be avoided simply by using this standard. In no event shall Infraspection Institute be liable to anyone for special, collateral, incidental or consequential damages in conjunction with or arising from use of this standard.



Other Infraspection Institute Standards Infraspection Institute began publishing guidelines for infrared thermography in 1988. Since their initial publication, Infraspection Institute guidelines have been adopted by hundreds of companies worldwide and incorporated into documents published by other recognized standards organizations such as the American Society for Testing and Materials (ASTM). Beginning in 2007, Infraspection Institute guidelines were renamed as standards to reflect their industry-wide acceptance and the best practices they embody. Several standards are available from Infraspection Institute. These standards cover equipment operation, temperature measurement, and specific applications. A complete list of current Infraspection Institute standards may be found online at www.infraspection.com. Infraspection Institute standards represent the work of many practicing infrared thermographers and other experts. We thank them for their valuable contributions.



Copyright © 2008, Infraspection Institute 1



Standard for Infrared Inspection of Insulated Roofs 2008 Edition



Table of Contents 1.0



Scope



Page 3



2.0



Referenced Documents



Page 3



3.0



Terminology



Page 3



4.0



Significance and Use



Page 4



5.0



Responsibilities of the Infrared Thermographer



Page 5



6.0



Responsibilities of the End User



Page 5



7.0



Instrument Requirements



Page 6



8.0



Limitations (Applicability of Constructions)



Page 6



9.0



Significant Environmental Parameters



Page 6



10.0



Required Conditions



Page 7



11.0



Inspection Techniques & Procedures



Page 8



12.0



Data Interpretation



Page 9



13.0



Verification



Page 10



14.0



Documentation



Page 10



Copyright © 2008, Infraspection Institute • 425 Ellis Street • Burlington, NJ 08016



This document may be reproduced for personal use and not for profit, without charge, provided you include all of the copyright and address information listed above. Failure to include this information with any reproduction is an infringement of the copyright and is subject to legal action and consequences. Copyright © 2008, Infraspection Institute 2



1.0



Scope



1.1



This standard covers procedures for conducting an infrared inspection at night to determine the location of wet insulation in roofing systems that have insulation above the deck and in contact with the underside of the waterproofing membrane. Inspections may be ground-based or conducted from an aircraft.



1.2



This standard provides a common document for the end user to specify infrared inspections and for the infrared thermographer to perform them.



1.3



This standard lists the joint responsibilities of the end user and the infrared thermographer that, when carried out, will result in the safest and highest-quality inspection for both.



1.4



This standard outlines specific content for documenting the results of an infrared inspection.



1.5



This standard may involve use of equipment in hazardous or remote locations.



1.6



This standard addresses criteria for infrared imaging equipment, such as spatial resolution and thermal sensitivity.



1.7



This standard addresses meteorological conditions under which infrared inspections should be performed.



1.8



This standard addresses operating procedures and operator qualifications.



1.9



This standard addresses verification of infrared data using invasive test methods.



1.10 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.



2.0



Referenced Documents



2.1



Occupational Safety and Health Standards for General Industry 29 CFR, Part 1910. US Department of Labor. Occupational Safety & Health Administration, Washington, DC.



2.2



Occupational Safety and Health Standards for the Construction Industry 29 CFR, Part 1926. US Department of Labor. Occupational Safety & Health Administration, Washington, DC.



2.3



Level-l Certified Infrared Thermographer Reference Manual. Infraspection Institute, Burlington, NJ.



3.0



®



Terminology



For the purpose of this standard, 2



2



3.1



Core sample - A small sample encompassing at least 13 cm (2 in ) of the roof surface area taken by cutting through the roof membrane and insulation and removing the insulation to determine its composition, condition, and moisture content.



3.2



Exception - an abnormally warm or cool portion of a roof that may be a potential problem for the end user.



Copyright © 2008, Infraspection Institute 3



3.3



Expansion joint - a structural separation or flexible connection between two building elements that allows free movement between the elements without damage to the roof or waterproofing system.



3.4



Infrared inspection - the use of infrared imaging equipment to provide specific thermal information and related documentation about a structure, system, object or process.



3.5



Infrared thermal imager (infrared camera) - a camera-like device that detects, displays and records the apparent thermal patterns across a given surface.



3.6



Infrared thermographer - a person who is trained and qualified to use an imaging radiometer.



3.7



Inspection window - the time period during which infrared inspections of insulated roofs can be successfully conducted.



3.8



Insulated roof - a roof whose insulation is between the deck and the membrane and is in direct contact with the underside of the membrane.



3.9



Membrane - a flexible or semiflexible roof covering or waterproofing material whose primary function is the exclusion of water.



3.10 Moisture meter probe - an invasive (electrical resistance or galvanometric type) test that entails the insertion of a meter probe(s) through the roof membrane to indicate the presence of moisture within the insulated roof. 3.11 Qualified assistant - a person provided and authorized by the end user to perform the tasks required to assist the infrared thermographer. He/she is knowledgeable of the operation and history of the roof(s) to be inspected and is trained in all the safety practices and rules of the end user. 3.12 Qualitative infrared thermography - the practice of gathering information about a structure, system, object or process by observing images of different patterns of infrared radiation, and recording and presenting that information. 3.13 Roof section - a portion of a roof that is separated from adjacent portions by walls or expansion joints. 3.14 Roofing system - see Insulated roof. 3.15 Standard - a set of specifications that define the purposes, scope and content of a procedure. 3.16 Thermogram - a recorded visual image that maps the apparent temperature pattern of an object or scene into a corresponding contrast or color pattern. 3.17 Thermographer - see Infrared thermographer.



4.0 4.1



Significance and Use The purpose of an infrared inspection of an insulated roof is to locate and document patterns of infrared radiation (exceptions) on the roof surface that are caused by wet insulation beneath the membrane. 4.1.1



4.2



Invasive testing is necessary to verify the presence of water in the insulation.



Providing opinions about the causes of exceptions, the integrity of the roofing system, or recommendations for corrective actions requires skills beyond those of infrared thermography. 4.2.1



Infrared thermography will be presented as a visual inspection technique to gather and present information about the roofing system at a specific time. Copyright © 2008, Infraspection Institute 4



4.3



5.0



4.2.2



Performing invasive testing is beyond the scope of infrared thermography.



4.2.3



Data from infrared inspections of insulated roofs may be used for assessing the condition of a roofing system or for quality assurance inspections of new installations, repairs, or retrofits.



This standard does not provide methods to determine the cause of latent moisture within an insulated roof or its point of entry. It does not address the suitability of any particular material or system to function satisfactorily as waterproofing or insulation.



Responsibilities of the Infrared Thermographer



5.1



Infrared inspections will be performed when environmental and physical conditions such as solar gain, wind, surface and atmospheric moisture and heat transfer are favorable to gathering accurate data.



5.2



The infrared thermographer will have knowledge of the materials and construction of insulated roofs sufficient to understand the observed patterns of radiation.



5.3



The infrared thermographer will be accompanied by a person who is responsible for the thermographer’s safety when accessing roofs.



5.4



Unless so qualified, the infrared thermographer will not perform any tasks that are normally performed by a construction tradesperson.



5.5



The infrared thermographer will comply with the security and safety rules of the end user and applicable safety standards.



5.6



The infrared thermographer will use thermal imaging and/or measurement equipment with capabilities sufficient to meet the inspection requirements.



6.0



Responsibilities of the End User



6.1



Prior to the inspection, the end user will inform the infrared thermographer of any past and current problems with the roof(s) to be inspected and the reasons for conducting the inspection.



6.2



Prior to the inspection, the end user will heat or cool the building to be inspected to a uniform air temperature throughout when requested by the infrared thermographer.



6.3



When requested, the end user will provide a qualified assistant familiar with the construction and history of the roof(s). This person will be responsible for gaining access to, and maintaining the security of, the end user’s facilities and premises.



6.4



The end user will ensure that the subject roof surfaces are dry and free of debris or construction materials for a period of at least 24 hours prior to the infrared inspection.



6.5



When requested and available, the end user will furnish building drawings and/or blueprints to the infrared thermographer.



6.6



The end user will take full responsibility for consequences resulting from actions taken, or not taken, as a result of information provided by an infrared inspection.



Copyright © 2008, Infraspection Institute 5



7.0 7.1



7.2



Instrument Requirements General 7.1.1



Infrared thermal imaging systems shall detect emitted radiation and convert detected radiation to a real-time visual signal on a monitor screen. Imagery shall be monochrome or multi-color.



7.1.2



Spectral Range: the infrared imaging system shall operate within a spectral range from 2 to 14 µm. A spot radiometer or nonimaging line scanner is not sufficient.



7.1.3



The infrared thermal imaging system shall have a Minimum Resolvable Temperature Difference (MRTD) of 0.2°C or less at 20°C.



Ground-based Inspections 7.2.1



7.3



Aerial Inspections 7.3.1



8.0



For walk-over inspections or inspections performed from an elevated vantage point, the infrared imaging system shall have sufficient resolution to permit recognition of exceptions as small as 0.15 m (6 inches) on a side from the chosen vantage point.



For aerial inspections, the infrared imaging system shall have sufficient resolution to permit recognition of exceptions as small as 0.3 m (12 inches) on a side from the chosen altitude.



Limitations (Applicability of Constructions)



8.1



Applicable constructions include insulated roofs containing any of the commercially available rigid insulation boards. This includes boards made of organic fibers, perlite, cork, fibrous glass, cellular glass, polystyrene, polyurethane, isocyanurate, and phenolic. Composite boards and tapered systems made from these materials can also be inspected as can roofs insulated with foamed-in-place polyurethane.



8.2



Wet applied insulations such as lightweight concrete and wet applied decks such as gypsum can be difficult to inspect since they may retain significant quantities of construction water.



8.3



When moisture sensitive materials are located under pavers, stone ballast, or layers of dry insulation, thermal anomalies on the surface of the roof are diminished.



8.4



For roofs with highly reflective surfaces (aluminized coatings or foils) in the spectral range of the infrared thermal imager, infrared inspections are not practical until the surface is naturally or temporarily dulled.



8.5



The wetting rates of roof insulations vary according to the type of insulation and environmental exposure. New roofs with insulations that wet slowly, such as cellular plastics or cellular glass, usually should not be inspected until they are at least three months old.



8.6



Infrared inspections are not intended to identify the source of the moisture.



9.0 9.1



Significant Environmental Parameters Water retained in roofing systems decreases the thermal resistance and increases the heat storage capacity of such systems. This can lead to thermal anomalies on the surface that can be located using an infrared thermal imager. These thermal anomalies depend upon the type of roofing system, the amount of moisture in the insulation, and the weather conditions. For a given roof, there are four weather related parameters that can cause significant changes in surface temperatures over wetted roof areas compared to dry areas. These are: inside to outside temperature difference, the rate of change of temperature in the hours prior to viewing, the amount of solar loading, and the wind speed. Copyright © 2008, Infraspection Institute 6



9.2



10.0



Acceptable weather conditions for nighttime infrared imaging inspections will be light winds with some combination of a large inside to outside temperature difference, a rapid decrease in ambient temperature in the late afternoon and a sunny day prior to the inspection. Typically, an infrared inspection during cold weather relies on a large inside to outside temperature difference. An infrared inspection during warm weather relies on solar loading. 9.2.1



Inside to Outside Temperature Difference: exceptions become more distinct as the inside to outside temperature difference increases.



9.2.2



Rate of Change of Temperature: the surface temperature over a wet roof area responds more slowly to a change in the air temperature than the surface temperature over a dry roof area. Thus, when the whole roof is cooling, wet areas will cool more slowly. The greater the rate of outside temperature change, the greater the difference in surface temperature between wet and dry areas.



9.2.3



Solar Loading: during the course of a sunny day, areas of the roof containing wet insulation will store more solar energy than dry areas causing these areas to cool more slowly during the evening. This effect increases as solar loading increases. Thus, the effect is greater in the summer than in the winter and greater on a clear day than on a cloudy day. Shaded areas receive less solar loading than unshaded areas.



9.2.4



Wind: air flow over a roof surface increases the convective heat transfer to the surrounding air significantly. This causes all surface temperatures to approach the ambient air temperature reducing the intensity of exceptions or making them undetectable.



Required Conditions



10.1 No appreciable precipitation shall have fallen on the roof during the 24 hours prior to the infrared inspection. 10.2 At the time of the infrared inspection, the surface of the roof shall be free of ponded water, snow, ice, debris, and piles of aggregate except that these conditions may exist in a few areas provided that those areas are delineated as being uninspected in the report. 10.3 At the time of the infrared inspection, winds in the area shall be less than 25 km/h (15 mph). 10.4 After a day of heavy overcast, infrared inspections shall not be conducted unless the outside temperature is at least 10°C (18°F) colder than the temperature of the space under the roof deck at the time of the inspection and for most of the prior 24 hours. In other weather, the indoor to outdoor temperature difference is not an issue except as indicated in 10.7 and 12.2. 10.5 Most infrared inspections can be conducted from one hour after sunset until sunrise. However, the inspection window will be dependent upon roof construction, amount of moisture in the roof, and local weather conditions both before and during the infrared inspection. It may be necessary to delay the start of inspections after warm cloudy days since cloud cover reduces both solar loading and nighttime radiational cooling. To check that a sufficient delay has been allowed after such days, the first portion of the infrared inspection shall be repeated before leaving the roof. 10.6 The formation of dew or frost on the roof will reduce the intensity of exceptions. It may not be possible to conduct infrared inspections under these conditions. 10.7 Infrared inspections of roofing systems ballasted with stone or pavers should only be conducted when the outside temperature at the time of the inspection and for most of the prior 24 hours has been at least 18°C (32°F) colder than the temperature of the space under the roof deck.



Copyright © 2008, Infraspection Institute 7



11.0



Inspection Techniques & Procedures



11.1 Infrared inspections may be conducted from a ground-based vantage point or from an aircraft. 11.1.1



Ground-based inspections may be conducted as follows:



11.1.1.1 Walk-over: maneuvering a man-portable infrared thermal imager while walking on the surface of a roof. The system may be hand carried or mounted on a cart. Thermograms are taken of areas of interest. Exceptions are outlined on the surface of the roof using spray paint or other semi-permanent means. Invasive verification is used to confirm the presence of moisture within the outlined areas. 11.1.1.2 Elevated vantage point: Use of a man-portable infrared thermal imager from an elevated vantage point may provide an improved view of the roof. 11.1.2



Aerial inspections may be conducted using an infrared imaging system from an aircraft. Thermograms are obtained for the entire roof and subsequently analyzed.



11.2 Prior to performing an infrared inspection, the infrared thermographer will ascertain, whenever possible, the construction of the roof system including the types and thicknesses of the membranes and insulations for each roof section of different construction. 11.2.1



Ideally, this should be accomplished via core sampling of the subject roofs prior to the infrared inspection.



11.3 The infrared thermographer will inform the end user of any limitations of the roof system design, weather, inspection techniques and/or the infrared inspection equipment, and will provide or recommend inspection techniques as necessary to perform a complete and accurate inspection. 11.4 Ground-based inspections 11.4.1



Prior to the infrared inspection, the infrared thermographer will visually inspect the roof system during daylight to locate means of access, identify possible safety hazards, identify heat sources beneath the roof, and determine the most effective procedure for inspecting the roof.



11.4.2



The infrared thermographer will exercise reasonable care while on the roof and will avoid damaging the roof membrane and other components of the roof.



11.4.3



Whenever possible, the underside of the roof should be visually examined to note conditions that may affect inspection results such as, room temperature, equipment, air movement, and changes in construction.



11.4.4



An infrared imaging system shall be maneuvered over the roof in an organized manner to ensure complete inspection viewing at an angle greater than 0.35 rad (20°) from the surface of the roof.



11.4.5



Exceptions shall be delineated on the surface of the roof in a semipermanent manner such as with spray paint.



11.4.6



Infrared data shall be verified in accordance with Section 13.



11.4.7



The location of all invasive test sites shall be marked on the surface of the roof.



Copyright © 2008, Infraspection Institute 8



11.5 Aerial inspections



12.0



11.5.1



Compliance: before aerial infrared inspections are conducted, the requirements of regulatory bodies such as the Federal Aviation Administration (FAA) must be met with regard to installed equipment, flight safety, security, and noise.



11.5.2



Execution: the infrared inspection shall be conducted so as to meet the conditions in 7.3. The findings of infrared imaging systems shall be viewed on a monitor in the aircraft during the flight to ensure that the roof has been inspected properly. The findings are also recorded for detailed study after the flight. The information required in Section 14 shall be obtained.



11.5.3



Visual: subject roofs shall be inspected visually during daylight hours within two days of when the aerial infrared inspection is conducted in order to provide a visual record of roof surface conditions which may affect the infrared inspection. The visual inspection can be accomplished by taking air photographs or by walking the roof. The condition of the roof surface shall not have changed appreciably in the period between the infrared inspection and the visual inspection.



11.5.4



Verification: infrared data shall be verified according to Section 13.



11.5.5



The location of all invasive test sites shall be marked on the surface of the roof.



Data Interpretation



12.1 The interpretation of infrared data from a roof is a process of pattern recognition for the purpose of differentiating exceptions caused by wet insulation from those caused by the following: 12.1.1



Variations in the type, thickness, density, or continuity of roof insulation.



12.1.2



Variations in membrane thickness, moisture content, or continuity.



12.1.3



Variations in the type or thickness of aggregate surfacing or ballast.



12.1.4



Variations within the roof deck or supporting structure.



12.1.5



Inconsistencies in the roofing system due to damage, repairs, coatings, or overlays.



12.1.6



Variations in temperature beneath the roofing system.



12.1.7



Fasteners, flashings, flanges, or projections from the roofing system or discontinuities within it.



12.1.8



Variations in roof surface emittance.



12.1.9



Infrared radiation from nearby sources.



12.1.10



Moisture or debris on the surface of the roof.



12.2 Most exceptions associated with wet insulation observed at night will be warmer than adjacent areas of the roof that contain dry insulation. However, the reverse may be true for roofs over refrigerated areas. 12.3 Exceptions associated with wet insulation generally fall into one of the following categories: boardstock, picture-framed, or amorphous.



Copyright © 2008, Infraspection Institute 9



12.3.1



Board-stock patterns are comprised of solid rectangular patterns generally associated with board by board wetting of perlite, cork, wood fiber, and glass fiber insulation.



12.3.2



Picture-framed patterns are comprised of rectangular outlined patterns generally associated with slow-wetting insulation boards such as cellular plastic and cellular glass. However, insulation boards that do not abut adjacent boards may give similar patterns even though the insulation is not wet.



12.3.3



Amorphous patterns are irregular in shape. They are generally associated with monolithic insulations such as lightweight concrete, gypsum, or foamed-in-place polyurethane. Such patterns can also be associated with layers of water above or below any insulation.



12.4 Accurate interpretation of infrared data requires verification.



13.0



Verification



13.1 Verification of infrared data must be carried out by the following invasive test methods: cores, or cores and moisture meter probes. 13.1.1



Cores shall be used to determine the composition and condition of the roofing system, and the quantity of moisture in the insulation.



13.1.2



Moisture meter probes may be used to indicate the presence of moisture in roofing systems provided that they are correlated with core moisture contents (see 13.4.2).



13.2 The penetrated roofing system at invasive verification sites must be repaired in a manner that will not impair its waterproof integrity. 13.3 Minimum verification shall meet these requirements: 13.3.1



One core in each roof section (see 3.1.13) to determine the composition of that section. This core can be of either wet or dry insulation so as to verify with the minimum number of cores.



13.3.2



One core or correlated moisture meter probe reading in an area of dry insulation for each roof section. However, at least one core in an area of dry insulation is required for each roofing system of different composition.



13.3.3



One core in each type of thermal pattern associated with wet insulation (see 12.3) for each roofing system of different composition.



13.4 Noninvasive testing equipment such as nuclear and capacitance meters may be used to compliment, but not replace invasive verification.



14.0



Documentation



14.1 The thermographer will provide documentation for all infrared inspections. The following information will be included in a written report to the end user: 14.1.1



The name and valid certification level(s) and number(s) of the infrared thermographer.



14.1.2



The name and address of the end user.



14.1.3



The name(s) of the assistant(s) accompanying the infrared thermographer during the inspection.



14.1.4



The manufacturer, model and serial number of the infrared equipment used. Copyright © 2008, Infraspection Institute 10



14.1.5



A description of the location and construction of the roof(s) that were inspected and notations of any portions that could not be inspected.



14.1.6



The date(s) of the inspection and when the report was prepared.



14.1.7



The time the exception was documented.



14.1.8



The weather conditions surrounding the exception including the inside and outside air temperatures, wind speed and direction and the sky conditions.



14.1.9



Hard copies of a thermal image (thermogram) and corresponding visible-light image of the exception. When approved by the end user, the infrared thermographer may provide sketches or drawings in place of, or in addition to, thermograms and photographs.



14.1.10



The field-of-view of the infrared camera lens.



14.1.11



Notation of any windows, filters or external optics used.



14.1.12



Any other information or special conditions that may affect the results, repeatability or interpretation of the exception.



14.1.13



A written narrative that summarizes:



14.1.13.1 The roof construction and materials including the insulation type and thickness, if known. 14.1.13.2 The results of any destructive or other nondestructive tests performed. 14.1.13.3 The inspection procedures and findings. 14.1.14



Painted outlines on the roof surface of areas suspected to contain wet insulation beneath the membrane.



14.1.15



An accurate drawing of the roof with appropriate scale, direction orientation and showing the roof areas that have been outlined with paint on the roof surface.



Copyright © 2008, Infraspection Institute 11



Standard for Measuring and Compensating for Transmittance of an Attenuating Medium Using Infrared Imaging Radiometers



2008 Edition



Infraspection Institute 425 Ellis Street Burlington, NJ 08016 www.infraspection.com



Standard for Measuring and Compensating for Transmittance of an Attenuating Medium Using Infrared Imaging Radiometers Foreword This standard outlines the procedures and documentation requirements for measuring and compensating for transmittance of an attenuating medium using an infrared imaging radiometer. This standard covers a technique which is both art and science. This document assumes that the reader is generally familiar with the science of infrared thermography. The use of this standard is not intended to qualify an individual using it to conduct an infrared inspection, or to analyze the resulting infrared data without formal training prior to its use. This document is intended to support infrared thermographers who have been professionally trained and certified. It must be acknowledged and understood that the misinterpretation of data that can occur without proper training and experience cannot be avoided simply by using this standard. In no event shall Infraspection Institute be liable to anyone for special, collateral, incidental or consequential damages in conjunction with or arising from use of this standard.



Other Infraspection Institute Standards Infraspection Institute began publishing guidelines for infrared thermography in 1988. Since their initial publication, Infraspection Institute guidelines have been adopted by hundreds of companies worldwide and incorporated into documents published by other recognized standards organizations such as the American Society for Testing and Materials (ASTM). Beginning in 2007, Infraspection Institute guidelines were renamed as standards to reflect their industry-wide acceptance and the best practices they embody. Several standards are available from Infraspection Institute. These standards cover equipment operation, temperature measurement, and specific applications. A complete list of current Infraspection Institute standards may be found online at www.infraspection.com. Infraspection Institute standards represent the work of many practicing infrared thermographers and other experts. We thank them for their valuable contributions.



Copyright © 2008, Infraspection Institute 1



Standard for Measuring and Compensating for Transmittance of an Attenuating Medium Using Infrared Imaging Radiometers 2008 Edition



Table of Contents 1.0



Scope



Page 3



2.0



Referenced Documents



Page 3



3.0



Terminology



Page 3



4.0



Summary of Test Method



Page 3



5.0



Significance and Use



Page 4



6.0



Precautions and Error Sources



Page 4



7.0



How to Measure the Transmittance of an Attenuating Medium



Page 4



8.0



How to Compensate for the Transmittance of an Attenuating Medium



Page 5



Copyright © 2008, Infraspection Institute • 425 Ellis Street • Burlington, NJ 08016



This document may be reproduced for personal use and not for profit, without charge, provided you include all of the copyright and address information listed above. Failure to include this information with any reproduction is an infringement of the copyright and is subject to legal action and consequences.



Copyright © 2008, Infraspection Institute 2



1.0



Scope



1.1



This test method covers procedures for measuring and compensating for transmittance when using an imaging radiometer to measure the temperature of an object through an attenuating medium, such as a window, filter, or atmosphere.



1.2



This test method may involve use of equipment and materials in the presence of heated or electrically energized equipment, or both.



1.3



This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.



2.0



Referenced Documents



2.1



Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers. Infraspection Institute, Burlington, NJ.



2.2



Standard for Measuring and Compensating for Emittance Using Infrared Imaging Radiometers. Infraspection Institute, Burlington, NJ.



2.3



Level-ll Certified Infrared Thermographer Reference Manual. Infraspection Institute, Burlington, NJ.



3.0



®



Terminology



3.1



Attenuating medium - a semi-transparent solid, liquid or gas, such as a window, filter, external optics or an atmosphere that attenuates infrared radiation.



3.2



Blackbody simulator - a device with an emittance close to 1.00 that can be heated or cooled to a known, stable temperature.



3.3



Filter - a semi-transparent material that attenuates certain wavelengths of radiation.



3.4



Infrared imaging radiometer (imaging radiometer) - a thermal imager capable of measuring temperature.



3.5



Infrared thermographer - a person who is trained and qualified to use an imaging radiometer.



3.6



Non-imaging radiometer - an instrument that measures the average apparent surface temperature of an object based upon the object’s radiance.



3.7



Reflected temperature - is the apparent temperature value reported by a radiometer that corresponds to the infrared energy incident upon, and reflected from the measured surface of an object.



3.8



Thermographer - see Infrared thermographer.



3.9



Window - a semi-transparent material that separates conditioned and unconditioned atmospheres. Windows may also attenuate certain wavelengths of infrared radiation.



4.0 4.1



Summary of Test Methods Using the computer built into an imaging radiometer, methods are given for: Copyright © 2008, Infraspection Institute 3



5.0



4.1.1



Measuring the transmittance of an attenuating medium.



4.1.2



Compensating for errors when measuring the temperature of an object through an attenuating medium when the emittance of the object and the transmittance of the attenuating medium are known.



4.1.3



Measuring and compensating for unknown transmittance and emittance errors when the object temperature is known.



Significance and Use



5.1



The transmittance of an attenuating medium can cause significant error when measuring the temperature of an object with an imaging radiometer through the medium. Test methods are given for measuring and compensating for this error source.



5.2



These methods can be used in the field or laboratory using commonly available materials.



5.3



These methods may also be used with non-imaging radiometers that have the required computer capabilities.



6.0 6.1



Precautions and Error Sources Method for Measuring the Transmittance of an Attenuating Medium 6.1.1



This test method requires a blackbody simulator with an emittance of 0.95 or greater that is at least 10°C warmer than ambient temperature. Potential errors can be minimized by ensuring the stability of the temperature difference between the source and the ambient temperature during the test. Also, the transmittance measurement accuracy can be increased by increasing this temperature difference.



6.1.2



The compositions and thicknesses of attenuating media can vary within the same object. Errors can be minimized by measuring through the same portion of the object every time.



6.2



The transmittance of an attenuating medium may be specific to the temperature of the medium and the spectral waveband of the radiometer used to make the measurement. Therefore, the temperature of the measured object and the spectral waveband of the radiometer used should be noted with the measured transmittance value.



6.3



These methods are valid only for objects that are opaque in the waveband of the imaging radiometer utilized.



7.0 7.1



How to Measure the Transmittance of an Attenuating Medium Equipment Required 7.1.1



A calibrated imaging radiometer with a computer that allows the thermographer to input reflected temperature (R) and emittance (E) values.



7.1.2



A blackbody simulator or a target with an emittance greater than 0.95 and which is heated close to the temperature of the target(s) you will be measuring in the field.



7.1.3



A window that is semitransparent in the waveband of the imaging radiometer. Copyright © 2008, Infraspection Institute 4



7.2



7.3



8.0 8.1



8.2



Method 7.2.1



Heat the blackbody simulator to a temperature close to the temperature(s) of the target(s) that you will be measuring in the field. Be sure to allow enough time for the blackbody simulator temperature to stabilize.



7.2.2



Place the imaging radiometer at the desired location and distance from the blackbody simulator. The use of a tripod or other support device is recommended. Aim and focus the imaging radiometer on the blackbody simulator.



7.2.3



Measure and compensate for the blackbody simulator’s reflected temperature. Refer to the Infraspection Institute Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers.



7.2.4



With the imaging radiometer’s emittance control set to 1.00, use an appropriate imager measurement function, such as spot temperature, cross hairs, or isotherms to define a measurement point or area in the center of the blackbody simulator. Measure and note the apparent temperature of the blackbody simulator.



7.2.5



Place the window directly in front of, and in contact with, the imaging radiometer’s lens.



7.2.6



Without moving the imager, adjust its emittance control until the indicated temperature is the same as the apparent temperature just taken in 7.2.4. The indicated emittance value is the transmittance percentage, T, of this window when measuring this temperature target with this waveband imaging radiometer.



7.2.7



Conduct procedures 7.2.1 through 7.2.6 a minimum of three times and average the transmittance percentage values.



Notes 7.3.1



Maintain a safe working distance from any high temperature blackbody simulators or targets.



7.3.2



Window thickness can vary. Be sure to sight through the same area each time you use the window.



How to Compensate for the Transmittance of an Attenuating Medium Equipment Required 8.1.1



A calibrated imaging radiometer with a computer that allows the thermographer to input reflected temperature (R) and emittance (E) values.



8.1.2



Procedure 8.2 requires an attenuating medium with a known transmittance value and a target with known emittance. Both E and T values should be calculated with the subject imaging radiometer at a temperature close to that of the target to be measured.



8.1.3



Procedure 8.3 requires an attenuating medium with an unknown transmittance value and a target having an unknown emittance value and a known surface temperature.



Measuring Object Temperature Through an Attenuating Medium with Known E and T Values 8.2.1



Position the imaging radiometer so that its lens views the target to be measured through the attenuating medium. When measuring through a window, the window should be in contact with the imaging radiometer’s lens. Aim and focus the imaging radiometer on target to be measured. Copyright © 2008, Infraspection Institute 5



8.3



8.4



8.2.2



Measure and compensate for the target’s reflected temperature (R). Refer to the Infraspection Institute Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers but input the transmittance percentage (T) of the attenuating medium (instead of 1.00) in the imaging radiometer’s computer under the “E” input when measuring the reflected temperature.



8.2.3



Calculate the combined transmittance and emittance correction value by multiplying the known attenuating medium transmittance percentage times the known target emittance (T x E). Note this combined correction value.



8.2.4



Compensate for transmittance and emittance by entering the combined correction value from 8.2.3 in the imaging radiometer’s computer under the “E” input.



8.2.5



With attenuating medium or window in place, measure the temperature of the object with the imaging radiometer. Use an appropriate imager measurement function, such as spot temperature, cross hairs, or isotherms to define a measurement point or area on the target.



Measuring Object Temperature Through an Attenuating Medium with Unknown E and T Values 8.3.1



Position the imaging radiometer so that its lens views the target to be measured through the attenuating medium. When measuring through a window, the window should be in contact with the imaging radiometer’s lens. Aim and focus the imaging radiometer on target to be measured.



8.3.2



Measure and compensate for the object’s reflected temperature. Refer to the Infraspection Institute Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers.



8.3.3



With the imaging radiometer’s emittance control set to 1.00, use an appropriate imager measurement function, such as spot temperature, cross hairs, or isotherms to define a measurement point or area on the target.



8.3.4



Without moving the imaging radiometer, adjust its emittance control until the indicated temperature matches the target’s known temperature. The indicated emittance value is the combined correction value for viewing this object at this temperature and waveband through the subject attenuating medium or window.



8.3.5



Conduct procedures 8.3.1 through 8.3.4 a minimum of three times to obtain an average correction value.



8.3.6



With attenuating medium or window in place, this combined correction value may be used to measure other areas of the target having similar emittance values and operating at similar temperatures.



Notes 8.4.1



Some imaging radiometers have an input for transmittance of a window commonly called “external optics” or “optics”. When conducting procedure 8.2, enter the percentage transmittance value under the external optics input and measure reflected temperature with the imaging radiometer’s E control set to 1.0. After compensating for reflected temperature, enter the known E value of target into the imaging radiometer’s computer.



8.4.2



Errors can occur if the temperature of the attenuating medium is different from the reflected temperature of the target whose temperature you are measuring.



Copyright © 2008, Infraspection Institute 6