Generac Power Systems Stationary Emergency Generator, Owner'S Manual

Page: 81 / 144

FUEL SYSTEM
FUEL REQUIREMENTS
The Stationary Emergency Generator may be equipped with one of
the following fuel systems:
• Natural gas fuel system
• Propane vapor (LPV) fuel system
Recommended fuels should have a Btu content of at least 1,000
Btu's per cubic foot for natural gas; or at least 2,520 Btu's per
cubic foot for LP gas. Ask the fuel supplier for the Btu content of
the fuel.
NOTE:
The fuel consumption requirements are identified in the
Specifications section of the Owner's Manual. Refer to the
Installation Manual if assistance is required for the sizing of
the pipe diameter for the generator. Any piping used to connect
the generator to the fuel supply should be of adequate size to
achieve the 100% load fuel consumption requirements identi-
fied in the Specifications section regardless of actual load.
NOTE:
The recommended fuel pressure is identified in the Specifications
section this manual.
NOTE:
It is the responsibility of the installer to make sure that only
the correct recommended fuel is supplied to the generator fuel
system. Thereafter, the owner/operator must make certain that
only the proper fuel is supplied.
NATURAL GAS FUEL SYSTEM
Natural gas is supplied in its vapor state. In most cases, the gas
distribution company provides piping from the main gas distribu-
tion line to the standby generator site. The following information
applies to natural gas fuel systems.
• Gas pressure in a building is usually regulated by national, state
and local codes.
• To reduce gas pressure to a safe level before the gas enters a
building, a primary regulator is needed. The natural gas supplier
may or may not supply such a regulator.
• It is the responsibility of the gas supplier to make sure sufficient
gas pressure is available to operate the primary regulator.
• Gas pressure at the inlet to the fuel shutoff solenoid must never
exceed approximately 14 inches water column (0.5 psi).
PROPANE VAPOR WITHDRAWAL FUEL SYSTEM
This type of system utilizes the vapors formed above the liquid
fuel in the supply tank. Approximately 10 to 20 percent of the tank
capacity is needed for fuel expansion from the liquid to the vapor
state. The vapor withdrawal system is generally best suited for
smaller engines that require less fuel. The installer should be aware
of the following:
• When ambient temperatures are low and engine fuel consump-
tion is high, the vapor withdrawal system may not function
efficiently.
• Ambient temperatures around the supply tank must be high
enough to sustain adequate vaporization, or the system will not
deliver the needed fuel volume.
• In addition to the cooling effects of ambient air, the vaporization
process itself provides an additional cooling effect.
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FuelSys001 R ev. F 04/11
Fuel System