pounds per hour to scfm

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pounds per hour to scfm

Postby keith » Sun May 22, 2005 12:07 am

I need to conver 20.2 lbs per hour to scfm can anyone help?
thanks
keith
 

Postby Guest » Sun May 22, 2005 12:54 am

You need to know the density at the "standard" conditions (the "s" in scfm). The hours and minutes are trivial.
Guest
 

pph to scfm

Postby keith » Mon May 23, 2005 4:55 pm

Anonymous wrote:You need to know the density at the "standard" conditions (the "s" in scfm). The hours and minutes are trivial.

gas is nitrogen at approx. 70f can this be used to calculate approx. value?
keith
 

Postby Guest » Mon May 23, 2005 6:23 pm

Yes, that's enough. The density of any gas is

rho = MP/RT

M is the molecular weight, 28.02 u
P is the pressure, 1 atm is normal for "standard conditions"
T is the absolute temperature. 60 °F and 68 °F are the usual "standard" temperatures in english unit gas measure. We'll assume 68 °F and convert it to Rankine, 527.7 R.
R is the gas constant, in English units, is 0.7302 atm-ft^3/(lbmol-R)

rho = 28.02 lb/mol x 1 atm/ (0.7302 atm-ft^3/(lbmol-R) x 527.7 R) = 0.0727 lb/ft^3.

Then 20.2 lb/hr x 1hr/60 min x 1 ft^3/.0727 lbs = 4.63 ft^3/m. Since I used the pressure and temp. of standard conditions, those are scfm.
Guest
 

Postby Guest » Mon May 23, 2005 7:59 pm

we found a chart in our rocket service manual you were right
on thanks
Guest
 


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