If Sm3/h is same as m3/h? 1

[valve321]

I know Sm3/h normally used for gas flow rate, is the value equal to m3/h

 

[TD2K]

I'm not quite sure what you are asking but I'll take a guess at it.

Assuming S stands for 'Standard' then at the temperature and pressure you're using for your 'standard' conditions, a gas flow of 1000 Sm3/h has an actual volume of 1000 m3/hr.

Change the pressure and temperature and while the Sm3/h will still be 1000, the actual volumetric flow rate will not likely be equal to 1000 actual m3/h.

Hope this helps.

 

[vzeos]

valve321,

Sometimes engineers use Sm3/h and m3/h interchangeably and use Am3/h to specify actual cubic meters per hour. The only way to be sure is to verify the pressure and temperature at which the volumetric flow rate was measured.

To correct to standard conditions (Q_s), you need to correct the flowing temperature(T_a) and pressure (P_a) to standard T - P conditions using the combined gas laws:

P_aQ_a/T_a=P_sQ_s/T_s

where the subscript a refers to actual conditions and the subscript s refers to standard conditions. Also, you may need to correct for compressibility depending on your operating pressure and your working fluid.

 

[zdas04]

RGasEng,
That equation works for up to about 200 psig (689 kPa), above that pressure, compressibility is too big a factor to ignore for most industrial gases and both "T" terms should be "T*Z".

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

The harder I work, the luckier I seem

 

[vzeos]

zdas04:

I agree. See the last sentence of my post… It is technically correct to say that both Z_a and Z_s should be included but Z_s can be taken as 1.00.

 

[MortenA]

valve321

Try to search these forums for "standard" and "normal" conditions and you will see that "standards" and "normal" have broard definitions in engineerings terms Anyway - its tru that sometimes the S (or N) is omitted - and you should be weary of this.

I can mention a program like "pipeline studio" from enegy solutions. Heer you can specify the flow in "m3/hr". Read closer in the help text and it fills in that they are referring to "standard conditions". BUT!!! These can be defined by the user. By default the correspond to 60 deg F and 1 atm (normally used for standard conditions in the imperial unit systems". The Sm3 is however defined at 15 deg C - but the user could specify any other standard condition!

I would recommend that you allways somewhere state what standard conditions (P&T) you refer to.

Best regards

Morten

 

[TD2K]

A point (stating your standard conditions) which Art would heartily agree to I believe.

I know of one of my co-workers which innocently asked the question, was initially brushed off and then watched the subsequent arguement as it turned out different groups in the meeting had different opinions of what 'standard conditions' meant.