8/7/2019 Choked Mass Flow Rate for Gases
2/2
gravitational conversion factor gc which is 32.17 ft/s2 in USA
units ... and since the
factor gc is 1 (kg-m) / (N-s2) in the SI metric system of units,
the above equations do
not include it.
The technical literature can be very confusing because many
authors fail to explainwhether they are using the Universal Gas Law
constant R which applies to any ideal
gas or whether they are using the gas law constant Rs which only
applies to aspecific individual gas. The relationship between the
two constants is Rs = R / (MW).
Notes:(1) The above equations are for a real gas.(2) For an
ideal gas, Z = 1 and d is the ideal gas density.(3) kgmol =
kilogram mole
References:
(1) Handbook of Chemical Hazard Analysis Procedures, Appendix B,
FederalEmergency Management Agency, U.S. Dept. of Transportation,
and U.S.Environmental Protection Agency, 1989.Handbook of Chemical
Hazard Analysis,Appendix B Click on the PDF icon, wait quite a bit
and then scroll down to page 391of 520 PDF pages.
(2) Risk Management Program Guidance For Offsite Consequence
Analysis, U.S. EPApublication EPA-550-B-99-009, April 1999.
Guidance for Offsite ConsequenceAnalysis (Appendix D: Equation D-1
in Section D.2.3 and Equation D-7 in SectionD.6)
Milton Beychok(Visit me at www.air-dispersion.com).
http://nepis.epa.gov/Exe/ZyNET.exe/10003MK5.TXT?ZyActionD=ZyDocument&Client=EPA&Index=1986+Thru+1990&Docs=&Query=&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=pubnumber%5E%22OSWERHCHAP%22&QFieldYear=&QFieldMonth=&QFieldDay=&UseQField=pubnumber&IntQFieldOp=1&ExtQFieldOp=1&XmlQuery=&File=D%3A%5Czyfiles%5CIndex%20Data%5C86thru90%5CTXT%5C00000003%5C10003MK5.TXT&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=10&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=p%7Cf&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=xhttp://nepis.epa.gov/Exe/ZyNET.exe/10003MK5.TXT?ZyActionD=ZyDocument&Client=EPA&Index=1986+Thru+1990&Docs=&Query=&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=pubnumber%5E%22OSWERHCHAP%22&QFieldYear=&QFieldMonth=&QFieldDay=&UseQField=pubnumber&IntQFieldOp=1&ExtQFieldOp=1&XmlQuery=&File=D%3A%5Czyfiles%5CIndex%20Data%5C86thru90%5CTXT%5C00000003%5C10003MK5.TXT&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=10&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=p%7Cf&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=xhttp://nepis.epa.gov/Exe/ZyNET.exe/10003MK5.TXT?ZyActionD=ZyDocument&Client=EPA&Index=1986+Thru+1990&Docs=&Query=&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=pubnumber%5E%22OSWERHCHAP%22&QFieldYear=&QFieldMonth=&QFieldDay=&UseQField=pubnumber&IntQFieldOp=1&ExtQFieldOp=1&XmlQuery=&File=D%3A%5Czyfiles%5CIndex%20Data%5C86thru90%5CTXT%5C00000003%5C10003MK5.TXT&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=10&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=p%7Cf&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=xhttp://www.epa.gov/emergencies/docs/chem/oca-all.pdfhttp://www.epa.gov/emergencies/docs/chem/oca-all.pdfhttp://www.air-dispersion.com/http://nepis.epa.gov/Exe/ZyNET.exe/10003MK5.TXT?ZyActionD=ZyDocument&Client=EPA&Index=1986+Thru+1990&Docs=&Query=&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=pubnumber%5E%22OSWERHCHAP%22&QFieldYear=&QFieldMonth=&QFieldDay=&UseQField=pubnumber&IntQFieldOp=1&ExtQFieldOp=1&XmlQuery=&File=D%3A%5Czyfiles%5CIndex%20Data%5C86thru90%5CTXT%5C00000003%5C10003MK5.TXT&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=10&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=p%7Cf&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=xhttp://nepis.epa.gov/Exe/ZyNET.exe/10003MK5.TXT?ZyActionD=ZyDocument&Client=EPA&Index=1986+Thru+1990&Docs=&Query=&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=pubnumber%5E%22OSWERHCHAP%22&QFieldYear=&QFieldMonth=&QFieldDay=&UseQField=pubnumber&IntQFieldOp=1&ExtQFieldOp=1&XmlQuery=&File=D%3A%5Czyfiles%5CIndex%20Data%5C86thru90%5CTXT%5C00000003%5C10003MK5.TXT&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=10&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=p%7Cf&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=xhttp://www.epa.gov/emergencies/docs/chem/oca-all.pdfhttp://www.epa.gov/emergencies/docs/chem/oca-all.pdfhttp://www.air-dispersion.com/
