7
REV F
60706-209
LP TANK SIZING
Tank Temperature
Tank Size
60° F (16° C)
150 Gallons
32° F (0° C)
250 Gallons
0° F (18° C)
500 Gallons
-20° F (-29° C)
1000 Gallons
NATURAL GAS (NG)
The primary regulator (fuel meter) on the building should deliver the
correct volume and pressure to the generator set. This regulator must
be sized to deliver the required BTU’s to the generator set and all other
appliances in the building. If the primary regulator (fuel meter) is a high
pressure regulator, then a low pressure regulator must be installed
to bring the pressure down to 4-6 oz. (7-11 inches water column) of
pressure. This low pressure regulator must be at least 10 feet from the
engine generator set; any closer installation will require a larger line
be installed to provide a fuel reservoir. If this is not done, the demand
regulator on the unit and the pressure regulator in the fuel line will
interfere with each other. This regulator must be sized to accommodate
the demand of the generator set and any other appliance connected to
it. See the following table for the correct size of pipe to be installed.
Feet*
Size of pipe
Up to 25 ft
¾” pipe
25 - 100 ft
1” pipe
Over 100 ft
Use a two regulator system
*Allow an additional 3 feet for each standard elbow. DO NOT use
‘street ells’ (restrictive).
WARNING: PERSONAL DANGER:
Do not use galvanized pipe in fuel line runs. The galvanized coating
can become eroded and flake off, causing possible obstructions in the
regulator or fuel valve. The results could range from inoperative engine
to hazardous fuel leaks.
CAUTION:
Be careful when sealing gas joints. Excessive sealing compound can
be drawn into the solenoid, regulator or carburetor causing an engine
malfunction.
FUEL PRESSURE
Correct fuel pressure cannot be stressed enough. The most common
cause for inoperative systems is an inadequate or incorrect fuel
pressure. Performance of the engine is in direct relation to the
correctness of the fuel system. Shown below is a diagram of a typical
LP vapor fuel installation. Notice the following tables give two different
units of measuring fuel pressure. The first and most accurate is the
use of a simple water manometer. A manometer is calibrated in inches
of water column . The second is with a pressure gauge calibrated in
ounces per square inch.
WARNING: FIRE HAZARD:
All fuel runs should be installed by a licensed fuel supplier.
To connect the fuel line to the generator set you will connect your
incoming fuel line to the 3/4 inch NPT fitting located on the left side
of the engine-generator set. This fitting is shipped with a plastic plug
installed to insure the fuel system stays clean. For all vapor fuel
systems the delivery pressure of the fuel to the fuel solenoid on the unit
must be four to six ounces psi (per square inch) or 7 to 11 inches
W.C. (water column). These fuel pressures are critical; failure to
provide the proper pressure can cause many problems ranging from a
unit that will not start to causing damage to the fuel system.
These units are normally tested on Natural Gas and will have a
tag hanging on the fuel hose indicating on what fuel your unit was
factory tested. If you are running on LP or have to change fuel types
at any time, see information on page 8 on NG/LP CONVERSION.
INSTALLING THE FUEL LINE
NOTICE:
The engine generator sets are properly adjusted before they
leave the factory. A tag is attached to the unit that specifies the fuel,
natural gas (NG) or propane vapor (LP) that the unit was set up and
tested on.
NATURAL GAS or LP VAPOR PIPE SIZE
Size of pipe normally required for generators operating on natural gas
or LP vapor. Unit location will determine the size of fuel line that is
required to supply the engine with a constant fuel pressure and volume.
LIQUID PROPANE VAPOR (LP)
Refer to the tables on the following pages for fuel line size and
recommended tank size. For distances of 100 feet or over, a two
regulator fuel system is recommended. This is accomplished by
installing a primary regulator at the tank which will reduce the tank
pressure down to 10 to 15 lbs. A low pressure regulator is installed to
further reduce the fuel pressure to the required four (4) to six (6) oz.
operating pressure. This low pressure regulator must be at least 10
feet from the engine generator set; any closer installation will require
a larger line be installed to provide a fuel reservoir. This is also true
for the single low pressure regulator, it should also be a minimum of
10 feet from the unit. If this is not done, the demand regulator on the
unit and the pressure regulator in the fuel line will interfere with each
other. When the two (2) regulator system is used on LP, a fuel line size
of 1/2 to 5/8 inch is generally adequate for distances up to 300 feet
from the primary to the low pressure regulator. Consult your local fuel
supplier for your exact requirements . The appropriate line size from
the following table is then installed from the low pressure regulator to
the generator set.
Feet*
Size of pipe
Up to 25 ft
¾” pipe
25 - 100 ft
1” pipe
Over 100 ft
Use a two regulator system
*Allow an additional 3 feet for each standard elbow. DO NOT use
‘street ells’ (restrictive).