Natural Gas Consumption

[voltsnamps]

Anyone know the formula for calculating the volume of natural gas used if the orfice size is known and the pressure is known? I am trying measure natural gas consumption for a residential application. I would love to have 4-20mA signal off of a residential gas line, but they are pricey. Anyone know of a reasonable way to measure this usage(besides a monthly gas bill)?

 

[kbs]

The formula for orifice flow is :
Q = 1658.5*A*k*the sq.root of (press.drop divided by the S.G. of the gas).

Q = cu.ft./hr
A = area of the orifice
k = coefficient of friction of the orifice
press. drop = normally the manifold pressure
S.G. of CH4 = .6

If the "k" factor is unknown, use .9 (90%)

Hope this helps.

kbs

 

[MintJulep]

Most residential equipment operates at a constant fire-rate, modulating by on-off control.

If this is in fact your case, and you can apply the formula that kbs provided then consumption is simply flow rate times operating time.

I suppose pricy is a relative term, but it seems like gas flow (or gas consumption, which seems like what you are really after) should be pretty common, and available from multiple sources, and hence pretty cheap.

 

[ChasBean1]

kbs, the A is in square inches? or square feet? (looks familiar but I haven't seen it in a while). Thanks, -CB

 

[pmover]

caution: whether or not the formula provided is applicable to low-pressure orifice systems is not known. also, the units of measurement are not provided. clarification is prudent.
while i'm not familiar with mfg, make, model #, etc., i've seen new residential properties that have remote metering monitoring capabilities install (i.e. telephone wire).
a suggestion - install a pd meter downstream of gas provider's meter and read the meter.
-pmover

 

[kbs]

Sorry about that. The units of measurement are:
Q = cu.ft./hr
A = sq.ft.
Press. drop = "w.c.

Also, as I have seen very few high pressure residential systems, I only provided a low pressure orifice flow formula.
Cheers, kbs.