Generac Power Systems NP Series - Manual (Page 31)

Section 6 - Installation INSTALLATION
PRIMEPACT 55G and 55LP Recreational Vehicle Generators
Figure 6.15 - Typical Propane Gas Fuel System ^ 6.5.4 PRIMARY REGULATOR
• 6.5.2 SOME IMPORTANT CONSIDERATIONS
When installing an LP gas system, consider seriously
the following items:
• All fittings, lines, hoses and clamps must be tight and
free of leaks. Apply a pipe sealant to threads when
assembling threaded connections. This reduces the
possibility of leakage.
• Test the entire fuel system for leaks using approved
test methods.
• Optimum gas pressure at the inlet to the gaseous fuel
solenoid valve and secondary regulator is 11 inches
water column.
• The installer’s fuel supply connection point is at the
gaseous fuel solenoid valve. This is a 3/4-inch
(female) connection. Provide a suitable 3/4-inch NPT
(male) connector to attach to the fuel supply line.
• Use a length of approved flexible fuel hose between
the gaseous fuel solenoid valve and rigid gas piping.
The flexible line should be at least 6 inches longer
than necessary.
• 6.5.3 VAPOR WITHDRAWAL ____________ _________
LP gas is stored in pressure tanks as a liquid. The gas
systems used with these generators were designed only
for vapor withdrawal type systems. Vapor withdrawal
systems use the gas vapors that form above the liquid
fuel in the tank. Do NOT attempt to use the generator
with any liquid withdrawal type system.
Gas pressure delivered to the solenoid valve must be
properly regulated by means of a primary gas regulator.
Mount the primary regulator at the gas tank outlet or in
the supply line from the gas tank. The following rules
apply:
• For best results, the primary regulator supplies
gaseous fuel to the secondary regulator at 11 inches
water column. Do NOT exceed 14 inches water col­
umn.
• The installer must be sure the primary regulator is
rated at sufficient gas flow to operate the generator
plus all other gas appliances in the circuit.
NOTE:
Recommended MINIMUM gas flow rate for all air­
cooled PRIMEPACT series generators is 67 cubic feet
per hour.
If an existing primary gas regulator does not have a
sufficient flow capacity for the generator and other
gas appliances in the circuit, (a) install a primary
regulator with adequate flow rate, or (b) install a sep­
arate regulator only and rated at least 67 cubic feet
per hour. The inlet side of any primary regulator that
supplies the generator must connect directly to a gas
pressure tank. Do NOT tee the generator line into a
gas circuit feeding other areas.
• 6.5.5 GASEOUS CARBURETION___________________
LP gas vapors should be supplied to the secondary reg­
ulator inlet at about 11 inches water column (positive
pressure). The engine pistons draw air in during the
intake stroke (Figure 2.16). This air passes through a
carburetor venturi, which creates a low pressure that is
proportional to the quantity of air being pumped. The
low pressure from the carburetor venturi acts on the
regulator diaphragm to pull the diaphragm toward the
source
of low pressure. A lever attached to the
diaphragm opens a valve to permit gas glow through the
carburetor.
Figure 6.16 - LP Gas Carburetion Diagram
AIR GAS AT
Generac* Power Systems, Inc. 23