Fuel Pressure; Power Loss; Fuel Type; The Gaseous Fuel System - Briggs & Stratton GC1031 GENSET Mode D'emploi

freezing. The termination of hard piping must include
a sediment trap (E) where condensate is not likely to
freeze.
• A minimum of one accessible, approved manual shutoff
valve (F) shall be installed in the fuel supply line within 6
ft (180 cm) of the generator.
• You must install a manual fuel shut-off valve in the interior
of the building.
• Where local conditions include earthquake, tornado,
unstable ground, or flood hazards, special consideration
shall be given to increase strength and flexibility of piping
supports and connections.
• Piping must be of the correct size to maintain the
required supply pressures and volume flow under
varying generator load conditions with all gas appliances
connected to the fuel system turned on and operating.
• Use a pipe sealant or joint compound approved for
use with NG/LP on all threaded fittings to reduce the
possibility of leakage.
NOTICE Keep thread sealant out of the gas piping to
prevent component part damage.
• Installed piping must be properly purged and leak tested,
in accordance with applicable codes and standards.
(A) Generator Fuel Inlet
(B) Flexible Fuel Line
(C) Union Fitting
(D) Manometer Test Port
(E) Sediment Trap
(F) Manual Shut-off Valve

Fuel Type

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 correct engine function,
factors that are inherent to each of these fuels, like your
location and the duration of possible utility interruptions, are
important considerations in the following fuel guidelines:
• Use clean, dry fuel that is free of moisture or
any particulate material. Using fuels outside the
recommendation values that follow can 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 and 20% of 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).

Fuel Pressure

Both LP vapor and natural gas fuel supply pressure at the
generator's fuel inlet port and must be between the following
levels at full load with all gas appliances turned on and in
operation.
• NG is 3.5-7" W.C.
• LP is 11-14" W.C.
Make sure that all gas line shutoff valves are OPEN and
that adequate fuel pressure is available whenever automatic
operation is desired.
For Natural Gas fuel pressure levels of 3.5 - 5" W.C., replace
the regulator assembly with service kit 6331-00 (available at
your local service dealer).

Power Loss

Air density is less at high altitudes, resulting in less available
engine power. Engine power will decrease by 3.5% for each
1,000 feet (300 m) above sea level and by 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 your Automatic
Transfer Switch manual on how to adjust for the power
decrease.

The Gaseous Fuel System

Fuel Pipe Sizing
NFPA 54 and 58 are common resources. The installer must
consider the specific gravity of gas, compensate for a nominal
amount of restriction from bends and fittings, and refer to
federal and local codes for guidance.

Fuel Conversion

The engine of your generator system is factory Calibrated and
set to operate on natural gas (NG). It can also be operated on
liquefied petroleum (LP) vapor.
NOTICE The initial factory NG settings are:
• Screw C: 2.5 turns
• Screw D: 0.5 turns
To configure 12kW units for LP fuel use:
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