Section 2 – Installation
IMPACT-36 plus II Recreational Vehicle Generator
◆2.4.2 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 gaseous fuel solenoid valve and rigid gas piping. The flexible line should be at least six (6) inches longer than necessary.
◆2.4.3 VAPOR WITHDRAWAL
Liquid propane (LP) gas is stored in pressure tanks as a liquid. The gas systems used with these genera- tors 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 kit along with any “liquid withdrawal” type system.
◆2.4.4 PRIMARY REGULATOR
Gas pressure delivered to the solenoid valve must be properly regulated by means of a primary gas regula- tor. Mount the primary regulator at the gas tank out- let or in the supply line from the gas tank, The fol- lowing rules apply:
•For best results, the primary regulator supplies gaseous fuel to the secondary regulator at 11 inch- es water column. Do NOT exceed 14 inches water column.
•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
IMPORTANT: IF AN EXISTING PRIMARY GAS REG- ULATOR 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 SEPARATE REGULATOR RATED AT LEAST 67 CUBIC FEET PER HOUR. THE INLET SIDE OF ANY PRIMARY REGULATOR THAT SUPPLIES THE GENERATOR MUST CONNECT DIRECTLY TO GAS TANK PRESSURE. DO NOT TEE THE GENERATOR LINE INTO A GAS CIRCUIT FEEDING OTHER APPLIANCES.
◆2.4.5 GASEOUS CARBURETION
LP gas vapors should be supplied to the generator regulator inlet at about 11 inches water column (pos- itive pressure). The engine piston draws 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 flow through the carburetor.
The greater the air flow through the carburetor ven- turi, the lower the pressure at the venturi throat, the greater the diaphragm movement and the greater the movement of the regulator valve. The more the regu- lator valve opens, the greater the gas flow that is pro- portional to air flow through the carburetor.
The following facts about the secondary regulator must be emphasized:
Figure 2.16 — Propane Gas Carburetion Diagram
26 Generac® Power Systems, Inc.