Gases conditions definitions 1

Please I need to confirm which are by definition Pressure and Temperature for Gases at Normal condition and Standard condition.

 

[MortenA]

Normal: 1 atm 0 deg C
Standard (SI ): 1 atm 15 deg C
Standard (imperial: 14.7 psia (=1 atm), 60 deg F=15.6 deg C

Best Regards

Morten

 

[grt12]

Note that atm is not an SI unit ! Standard conditions in SI are 101.3 kPa and 15.6 deg C though often 100 kPa and 15 deg C are used.

 

[MortenA]

all right true enough atm is not SI and kPa is - but here in Denmark (+ rest of scandinavia) i dont know many who uses kPa (most Bar/barg)

BUT You _cant_ use 100 kPa for your Normal/standard definition! Its 101.325 kPa if you insist!

AND its NOT 15.6 deg C for standard BUT 15.0 deg C (yes i know is a wrong rounding but thats how its defined)

Best Regards

Morten

 

[y3]

Conejo99,

Yours is a good question, and has elicited some good replies. It points out the myth of SI being a universal system. Each country has its own set of SI units, especially when "Standard Conditions" are defined for such purposes as metering of gas flows or quantification of gas volumes for commerce or custody transfer. Use the SI and/or other units that are defined in the commerce and trade laws of the country that your project pertains to. Most countries define these "standards", and may even give the numerical values for the units to be used. Good luck to you.

 

[TD2K]

I echo Y3, 'standard' conditions can vary between companies and industries, especially the gas industry here in the US.

Don't just accept 'standard' conditions, ensure that those conditions are specified. It doesn't really matter what is used, as long as all parties use the same basis (although some industries will definitely have a commonly used basis).