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regulator in the fuel line will interfere with each other.
When this two (2) stage regulator system is used, 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
secondary regulator. (Consult your local fuel supplier
for your exact requirements.) The appropriate line size
from the table below is then installed from the second
regulator to the generator set.
*************
***** 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 start to hazardous fuel leaks.
Size of pipe normally required for generators operating on
NATURAL GAS or LP vapor
up to 25 feet* 25 - 100 feet* over 100 feet*
PSS8000 3/4" pipe 1" pipe not recommended
PSS12000 3/4” pipe 1” pipe use a two
PSS20000 1" pipe 1.25" pipe regulator system
*Allow an additional 3 feet for each standard elbow. Do not use
‘street ells’ (restrictive)*
Size of pipe normally required for generators operating on
LP liquid withdrawal
PSS20000 - 3/8” line for all distances.
**** 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.
TWO (2) REGULATOR FUEL SYSTEM
Supply Primary Secondary Generator
Tank Regulator Regulator Set
1 2 3 4
SINGLE REGULATOR FUEL SYSTEM
Supply Primary Generator
Tank Regulator Set
1 3 4
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
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