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Generac
®
Power Systems, Inc. 5
1.6 GENERATOR FUEL SYSTEM
The unit has been factory tested and adjusted using a
natural gas fuel system. If propane (LP) gas is neces-
sary, refer to Section 1.12 for conversion.
Fuel pressure for a natural gas set up should be five
inches to 14 inches of water column (0.18 to 0.5
psi) at all load ranges.
Fuel pressure for an LP vapor set up should be 11
inches to 14 inches of water column (0.4 to 0.5
psi) at all load ranges.
NOTE:
A seperate gas line and regulator may be needed
to assure proper gas pressure to the generator.
Improper gas pressure can cause hard starting and
affect engine durability.
Gaseous fuels such as natural and LP
(propane) gas are highly explosive. Even the
slightest spark can ignite such fuels and cause
an explosion. No leakage of fuel is permitted.
Natural gas, which is lighter than air, tends to
collect in high areas. LP gas is heavier than air
and tends to settle in low areas.
1.7 ENGINE PROTECTIVE DEVICES
The engine has several safety switches which cause
the engine to automatically shut down under the fol-
lowing conditions: low oil pressure, high coolant tem-
perature, engine overspeed, low coolant level or over-
crank (Figure 1.3).
Figure 1.3 - Engine Protective Devices
1.7.1 LOW OIL PRESSURE SWITCH
This switch is normally-closed (N.C.) but is held open
by engine oil pressure during engine running. Should
operating oil pressure drop below about 8-10 psi
(55-68 kPa), the switch contacts close, the engine
shuts down automatically, and the low oil pressure
LED is turned ON (Figure 1.4).
NOTE:
The Low Oil Pressure, High Coolant Temperature
and Low Coolant Level are not monitored for the
first 10 seconds of engine run time.
Figure 1.4 - Low Oil Pressure Switch
1.7.2 HIGH COOLANT TEMPERATURE
SWITCH
Normally open (N.O.) thermostatic switch has sens-
ing tip which is immersed in captive coolant. Should
coolant temperature exceed about 230°F (110°C), the
switch contacts close. This causes the engine to shut
down automatically and turns on the high coolant
temperature/low coolant level LED (Figure 1.5).
Figure 1.5- High Coolant Temperature Switch
1.7.3 LOW COOLANT LEVEL SWITCH
Should engine coolant level drop below the level of
the high coolant temperature switch, it is possible for
the engine to overheat without automatic shutdown.
To prevent such overheating without automatic shut
down, the engine has a low coolant level sensor. If the
engine coolant drops too low, the engine automatical-
ly shuts down and turns on the high coolant temper-
ature/low coolant level LED (Figure 1.6 on page 6).
Low Coolant
Level Sensor
Low Oil Pressure Switch
High Coolant
Temperature Switch
!
Section 1 - General Information
Guardian 40kW Liquid-cooled Generators