Critical Flow Sub-Critical Flow [PDF]

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K(Cp/Cv) Kd



1.065



(Ratio of specific heat)



0.975



(Kd=0.975 when a PSV is installed with/without a RD in combination) (Kd=0.62 when a PSV isnot installed and sizing is only for RD)



59.705882352941 21 14.5 32.411764705882 855.6 Relieving Temperature 24669.603524229



Pset (psig) overpressure % Patm (psia) Pback press.(psia) T1(R) W (lb/hr)-required- critical V (scfm)-required- critical Z



0.86 1



(For Conventional & Pilot-operated Valve, Kb=1, for Balanced , Kb read from Page 37, API-RP-520)



1



(Kc:0.9, when RD is installed in combination with a PRV AND Kc:1, when RD not installed)



Kb (correction factor-back pressure)



Kc(Combination Factor) M.W.



110.3



M.W. at inlet releiving Condition



86.744117647059 Upstream Releiving Pressure 322.87906099745 51.363751672356 Critical Flow Nozzle Pressure



P1(psia) C Pcf(psia)



critical flow critical flow



Av- required-in2Aw- required-in2 refer to table and find the correct Area-in2 W-Critical-lb/hr-Actual



sub-critical flow r f1 F2- Coefficient of sub-critical flow 0 Av- required-in2 2.3333210344857 Aw- required-in2 2.853 refer to table and find the correct Area 30164.035644645 W-SubCritical-lb/hr-Actual



al flow 0.373647984 0.093100805 0.490062324 0 2.642813298 2.642813298 24669.60352



K(Cp/Cv) Kd TW (R) Tn (R) Pn (psia) Pset (psig) overpressure % Patm (psia) D (in) L (in) Pback press.(psia)



1.2 0.975 vessel wall temp. normal operating gas normal operating gas 75 10 14.7 Vessel diameter vessel height 77.2



P1(psia) T1(R) C F' A'(in2) Lcalculated(in0 A(in2) Pcf(psia)



97.2 upstream releiving pressure #DIV/0! relieving temp 337.2362087673 #DIV/0! 0 surface area of vessel 0 #DIV/0! 54.86686600123 Sub critical flow critical flow



Z Kb (correction factor-back pressure) Kc(0.9:RD installed ; 1: RD not installed) M.W. V (scfm) -required - critical W (lb/hr)-required- critical



sub-critical flow 0.84 1 1 65 #DIV/0! #DIV/0!



refer to table and find the correct Area V-Critical -scfm-actual W-Critical-lb/hr-Actual



r f1 F2 Vscfm-required W (lb/hr)-required- subcritical



refer to table and find the correct Area #DIV/0! #DIV/0!



V-SubCritical -scfm-actual W-SubCritical-lb/hr-Actual



al flow 0.794238683 0.18306384 0.86497344 #DIV/0! #DIV/0!



#DIV/0! #DIV/0!