Fuel Factors - GE 040374 Installation And Start-Up Manual

Fuel Factors

An important consideration affecting the entire installation
is the type of fuel used by your generator. The system was
factory tested and adjusted using natural gas, but can
be converted to use LP vapor. For proper engine function,
factors that are inherent to each of these fuels, your
location and the duration of possible utility interruptions are
important considerations in the following fuel guidelines:
• Use clean, dry fuel, free of moisture or any
particulate material. Using fuels outside the
following recommended values may cause
performance problems.
• In engines set up to run on propane (LP), commercial
grade HD5 propane with a minimum fuel energy of
2500 BTUs/ft3 with maximum propylene content of
5% and butane and heavier gas content of 2.5% and
minimum propane content of 90% is required.
Natural gas rating will depend on specific fuel but typical
derates are between 10 to 20% off the LP gas rating.
Natural gas or LP engines are certified to operate on natural
or liquid propane gas. The emissions control system for this
engine is EM (Engine Modifications).
WARNING Propane and Natural Gas are extremely flammable
and explosive, which could cause burns, fire or
explosion resulting in death or serious injury.
• The residential generator is equipped with an automatic safety
gas "fuel shut-off" valve.
• DO NOT operate the equipment if the "fuel shut-off" valve is
missing or inoperative.
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Fuel Pressure
Both LP vapor and natural gas fuel supply pressure at the
generator's fuel inlet port should be between the following levels
at full load with all gas appliances turned on and operating.
• NG is 3.5-7" W.C.
• LP is 11-14" W.C.
Ensure that all gas line shutoff valves are OPEN and that
adequate fuel pressure is available whenever automatic
operation is desired.
Power Loss
Air density is less at high altitudes, resulting in less available
engine power. Specifically, engine power will decrease 3.5%
for each 1,000 feet (300 m) above sea level and 1% for
each 10° F (5.6°C) above 77°F (25°C). Generators located in
these conditions must have their transfer switch adjusted
appropriately for this power decrease. See Automatic
Transfer Switch manual on how to adjust for the power
decrease.
Fuel Pipe Sizing
There are numerous on-line or otherwise-published
references for fuel pipe sizing. For example, NFPA 54 -
National Fuel Gas Code, 2006 (Item #: 320-6031-06) is a
common resource.
The installer should consider the specific gravity of gas
and compensate for a nominal amount of restriction from
bends, fittings, etc. If an unusual number of fittings, bends, or
other restrictions are used, refer to federal and local codes
for guidance.