PAGE 5
7340-20
60706-186
Size of pipe normally required for generators operating on
NATURAL GAS or LP VAPOR
up to 25 feet*
25 - 100 feet*
over 100 feet*
use a two
PSS15B2W 3/4” pipe
1” pipe
regulator system
*Allow an additional 3 feet for each standard elbow. Do not use
‘street ells’ (restrictive)*
**** 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
L.P. & N.G. VAPOR FUEL
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 block diagram of a typical L.P.
or N.G. vapor fuel installation.
Notice the following tables give two (2) 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.
Reference numbers 1 through 3 in the block diagrams
above are system parts supplied by customer.
Reference number 4 is the engine generator set.
Below is a table of the fuel pressure reading at each
reference in the system.
Fuel Pressure Table
Single Regulator (L.P. Vapor only)
1
3 4
UNIT OFF
TANK PSI
7-11 in
7-11 in
4-6 oz
4-6 oz
STARTING
TANK PSI
7-11 in
7-11 in
4-6 oz
4-6 oz
NO LOAD
TANK PSI
7-11 in
7-11 in
4-6 oz
4-6 oz
FULL LOAD TANK PSI
7-11 in
7-11 in
4-6 oz
4-6 oz
Two (2) Regulator System (L.P. Vapor only)
1
2
3
4
UNIT OFF
TANK PSI
10-15 lbs
7-11 in
7-11 in
4-6 oz
4-6 oz
STARTING
TANK PSI
10-15 lbs
7-11 in
7-11 in
4-6 oz
4-6 oz
NO LOAD
TANK PSI
10-15 lbs
7-11 in
7-11 in
4-6 oz
4-6 oz
FULL LOAD TANK PSI
10-15 lbs
7-11 in
7-11 in
4-6 oz
4-6 oz
Natural Gas
1
3
4
UNIT OFF
LINE PSI
7-11 in
7-11 in
4-6 oz
4-6 oz
STARTING
LINE PSI
7-11 in
7-11 in
4-6 oz
4-6 oz
NO LOAD
LINE PSI
7-11 in
7-11 in
4-6 oz
4-6 oz
FULL LOAD LINE PSI
7-11 in
7-11 in
4-6 oz
4-6 oz
LP/NG FUEL CONVERSION
To make a fuel conversion you will have to first remove
the end panel of the enclosure on the air intake end.
These units are normally tested on Natural gas and will
have the fuel line connected to the N.G. port on the fuel
outlet tee.
If you are going to operate on LPG you will need to move
the fuel line from the NG port to the LPG port on the fuel
outlet tee. These two ports have different orifice inserts
installed in them, which provide proper engine operation
with no further adjustments.
Fuel Outlet Tee
Fuel Line to Engine
Natural Gas
Connection
LP Gas
Connection
