Fuel Consumption; Fuel Pressure; Power Loss; Fuel Pipe Sizing - Briggs & Stratton Generator System Installation & Start-Up Manual

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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:

particulate material. Using fuels outside the

following recommended values may cause

performance problems.

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).

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.

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 meters) above sea level and 1% for

each 10° F (5.6°C) above 77°F (25°C). Make sure you and

your installer consider these factors when determining total

generator load.

Fuel Pipe Sizing

There are numerous on-line or otherwise-published

references for fuel pip sizing. For example, NFPA 54-Natural

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.