Install Manual

Fuel Conversion/Gas Connections
Installation Guidelines for Air-Cooled Generators 21
5.4 — Fuel Line Sizing
• First, determine what size pipe is required. Refer to NFPA 54 for NG or NFPA 58 for LP for further information.
• Always refer to the owner’s manual for the proper BTU / megajoule and required gas pressures. To calculate
BTU or Megajoules:
– Natural Gas: BTU = Cubic feet / hour x 1000
Megajoules = Cubic meters / hour x 37.26
– Liquid Propane Vapor: BTU = Cubic feet / hour x 2500
Megajoules = Cubic meters / hour x 93.15
• Start by measuring the distance from the generator to the gas source. The generator should be plumbed directly
from the source, not off the end of an existing system.
• When measuring the pipe length, add 2.5ft. (.76m) for every angle or bend in the pipe and add that to the overall
pipe distance.
5.4.1— Natural Gas Pipe Sizing
To properly use this chart, find the kW rating of the generator in the left column, and trace to the right. The number to
the right is the maximum length (measured in feet / meters) allowed for the pipe sizes on top. The pipe sizes are mea-
sured by inside diameter (ID) to include any fittings, valves (must be full flow), elbows, tees or angles. Add 2.5 ft (.76 m)
per any bend, tee or angle in the pipe to the overall distance.
Pipe Size (in. / mm)
kW .75 / 19 1 / 25 1.25 / 32 1.5 / 38 2 / 51
8 55 / 16.76 200 / 60.96 820 / 249.94
11 20 / 6.1 85 / 25.91 370 / 112.78 800 / 243.84
16 40 / 12.19 190 / 57.91 425 / 129.54
20 20 / 6.1 130 / 39.62 305 / 92.96 945 / 288.04
22 20/6.1 130 / 39.62 305 / 92.96 945 / 288.04
For 5-7 in of water column (9-13 mm mercury).
Pipe Size (in. / mm)
kW .75 / 19 1 / 25 1.25 / 32 1.5 / 38
8 20 / 6.1 60 / 18.29 175 / 53.34
11 30 / 9.14 125 / 38.1 200 / 60.96
16-20 10 / 3.05 60 / 18.29 125 / 38.1
22 10 / 3.05 60 / 18.29 125 / 38.1
For pressures below 5 in of water column (9 mm mercury) down to 3.5” of water
column (7mm mercury).