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The greater the airflow through the carburetor ven-
turi, the lower the pressure at the venturi throat. The
lower the pressure at the venturi throat, the greater
the diaphragm movement, and the greater the move-
ment of the regulator valve. The more the regulator
valve opens, the greater the gas flow that is propor-
tional to airflow through the generator.
The following facts about the secondary regulator
must be emphasized:
• The regulator must be sensitive to venturi throat
pressure changes throughout the operating range.
• The regulator must be properly adjusted so it will
stop the flow of gas when the engine is not running
(no air flow through the carburetor).
• The slightest airflow (and vacuum in the venturi
throat) should move the regulator valve off its seat
and permit gas to flow.
2.4.6 FUEL
SUPPLY LINES
• LP gas lines must be accessible, but protected
against possible damage.
• Do NOT connect electrical wiring to any LP gas fuel
line or run wiring alongside the lines.
• Route gas lines away from hot engine exhausts.
• Retain gas lines with metal clamps that do not have
sharp edges.
• Install an approved length of flexible hose between
the gaseous fuel solenoid valve and rigid fuel
supply lines. The flexible line must be nonmetal-
lic, nonorganic and nonconductive. It must be
approved for use with LP gas.
2.4.7 EXCESS FLOW VALVE
LP gas tanks should have an excess flow valve,
according to NFPA 501C, Paragraph 3-4.4. This
valve and the gas lines must be carefully sized so the
valve will close when a fuel line is severed or broken.
Consult the Natural-LP Gas Association for informa-
tion and limitations of excess flow valves.
Manual shutoff valves on the supply tank and else-
where in the system must be fully open when oper-
ating the generator. The excess flow valve functions
properly only if all valves are fully open.
2.4.8 LEAKAGE
TESTS
Do not place the generator into service until the gas
system has been properly tested for leaks. To test the
system, a separate source of 12 volts DC is needed to
open the gaseous fuel solenoid valve.
The leak test must comply fully with NFPA, Paragraph
318. All connections, hoses, valve regulators, fittings,
and other fuel system parts must be tested under
gas or air pressure of not less than 90 psi (620 kPa),
while using soap and water or an equivalent solution
to check for leaks. Other approved methods of testing
for leaks may be used, if appropriate. DO NOT USE
ANY FLAME TO TEST FOR LEAKS.
DANGER
Gaseous fuel lines between the tank and the
secondary regulator are under a positive pres-
sure (about 11 inches water column). Gas pres-
sure at the outlet side of the secondary regula-
tor, however, is a negative pressure and can
draw flame inside a line or fitting and cause an
explosion.
2.5 EXHAUST SYSTEM
The generator exhaust system must be safely and
properly installed. Only approved mufflers and other
exhaust system parts must be used. A properly
installed exhaust system must be vapor tight, quiet
and completely safe.
DANGER
The generator engine gives off DEADLY carbon
monoxide gas through its exhaust system. This
dangerous gas, if breathed in sufficient con-
centrations, can cause unconsciousness or even
death. Never operate the generator set with
the vehicle inside any garage or other enclosed
area. DO NOT OPERATE THE GENERATOR IF THE
EXHAUST SYSTEM IS LEAKING OR HAS BEEN
DAMAGED. SYMPTOMS OF CARBON MONOXIDE
POISONING ARE (a) inability to think coher-
ently; (b) vomiting; (c) twitching muscles; (d)
throbbing temples; (e) dizziness; (f) headaches;
(g) weakness; and (h) sleepiness. IF FEELING
ANY OF THESE SYMPTOMS, MOVE INTO FRESH
AIR IMMEDIATELY. IF SYMPTOMS PERSIST, GET
MEDICAL HELP. Do not operate the generator
until its exhaust system has been inspected and
properly repaired.
Never tee the generator engine exhaust pipe
into the vehicle engine exhaust piping. This
causes excessive back pressure on the generator
engine. Also, water from one engine can dam-
age the other engine.
Section 2 – Installation
Recreational Vehicle Generator
