sizing gas line

Tim_14

I have to size a gas line for 8 250,000 gas furnaces
with a gas pressure of .25 the units are 300ft away from point of delivery what size or sizes would you use

Earthfire

pipe size

check the Fuel gas code handbook or the burnham heating helper if you have one handy

Unknown

Are they seperatd or all on the same line. and .25

what lbs or inches water column.

If you have the following specs.

Specific Gravity .6

Pressure under 1lb (27.6" WC)

Allowable pressure drop .3

Schedule 40 pipe at 300 feet for 2,000,000 BTUs (2,000 CFH)

4" pipe will handle up to 2,780 CFH

3 1/2" pipe would be up to 1,996 CFH

hope this helps this was from Table 9.5 page 54-60 in National Fuel Gas Code book 1999 Edition ANSIZ223.1/NFPA 54

Larry_7

Need more info

Are all 8 furns 300 ft away or do you mean the furthest one? If furns are at different lengths from the meter, the trunk is sized for capacity at 300 ft but capacity is reduced after each take-off as the demand is reduced by the input dropped at each take-off. Continue to use the 300 ft length throughout. Per the 1996 Int'l Mech Code, if the building is a multiple-family dwelling, the total demand may be reduced to 90% total demand (diversity factor).

If the diversity factor can be used (1800 cfh), 3" Sch 40 pipe will carry 1975 cfh @ .5" press. drop.

Another approach may be to get 2psi from the utility and run CSST. My table shows 300 ft of 1-1/2" CSST will carry 1994 cfh with a 1 psi press. drop. Capacities vary by manufacturer. This stuff isn't cheap and requires additional regulators to cut to distribution press. before the appliances but may be more economical after weighing against the labor and equipment to run large black iron. CSST also requires certification from the manufacturer.

Hope this helps

Larry

Unknown

Forgot to mention in previous post

I have a guide for sizing pipe if you are interested.