Gaseous Fuel Systems
Installation Guidelines For Spark-Ignited Stationary Generators 15
Section 4: Gaseous Fuel Systems
Fuel Requirements and
Recommendations
NOTE: NG is lighter than air and will collect in high
areas. LP gas is heavier than air and will settle in low
areas.
LP gas should only use a vapor withdrawal system. This
type of system uses vapors formed above liquid propane
in the storage tank.
The unit will run on NG or LP gas, but has been factory-
configured to run on NG.
NOTE: Should the primary fuel need to be changed to
LP gas, the fuel system needs to be reconfigured. See
Fuel System Conversion for instructions on converting
fuel system.
BTU Content
Recommended fuels should have a BTU content of at
least 1,000 BTU/ft
3
(37.26 MJ/m
3
) for NG; or at least
2,500 BTU/ft
3
(93.15 MJ/m
3
) for LP gas.
NOTE: BTU fuel content information is available from the
fuel supplier.
Fuel Pressure
Required fuel pressure for NG is 3.5–14 in water column
(0.87–3.48 kPa) and LP gas is 7–14 in water column
(1.74–3.48 kPa). Always verify fuel pressure using the
appropriate specification sheet for the generator.
NOTE: The primary regulator for LP gas supply is NOT
INCLUDED with generator.
NOTE: All pipe sizing, construction, and layout must
comply with ICC IFGC, NFPA 54 for NG applications, and
NFPA 58 for LP gas applications. Verify fuel pressure
NEVER drops below required specification once genera-
tor is installed. See the NFPA website at www.nfpa.org
for further information regarding NFPA requirements.
Always contact local fuel suppliers or fire marshal to ver-
ify codes and regulations for correct installation. Local
codes will mandate correct routing of gaseous fuel line
piping around gardens, shrubs, and other landscaping.
Piping strength and connections should be given special
consideration when installation takes place in areas at
risk for; flooding, tornadoes, hurricanes, earthquakes,
and unstable ground.
NOTE: Use an approved pipe sealant or joint compound
on all threaded fittings.
NOTE: All installed gaseous fuel piping must be purged
and leak tested prior to initial startup in accordance with
local codes, standards, and regulations.
Fuel System Conversion
Commercial units are factory-configured and EPA certi-
fied with the fuel system ordered. Units are factory-con-
figured for NG, and can be reconfigured for LP in the
field.
Any one of the following gaseous fuel systems may be
installed:
• Natural Gas (NG)
• LP Gas Vapor Withdrawal
To convert to a different fuel (for example, from NG to LP
gas vapor), see owner's manual or contact an IASD.
Gaseous Fuel Properties
Natural Gas
NG is lighter than air. It is found in the gaseous state at
normal ambient temperatures and pressures. It is highly
explosive and can be ignited by the slightest spark. For
this reason, fuel lines must be free of leaks and adequate
ventilation is required. Local fuel/gas codes dictate maxi
-
mum pressure under which NG can be delivered to a site
or structure. Supply pressure from utility meter/regulator
is usually not the same as required by generator, so a
separate primary regulator providing the correct pressure
and volume of fuel to generator is required. If local utility
source fuel pressure is less than required by generator, it
is up to local utility to provide volume of fuel at the
required pressure.
(000192)
DANGER
Explosion and fire. Fuel and vapors are extremely
flammable and explosive. No leakage of fuel is
permitted. Keep fire and spark away. Failure to do
so will result in death or serious injury.
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