Install Manual
Gaseous Fuel Systems
Installation Guidelines For Spark-Ignited Stationary Generators 19
LP Gas System
LP gas uses vapors formed above liquid propane in sup-
ply tank. The maximum tank fill capacity is 80% and a
minimum of approximately 20% of tank capacity is
needed for fuel expansion from liquid to vapor state. Fuel
pressure and volume requirements for a LP gas system
at the connection point of the generator are listed on the
unit specification sheet.
Pressure regulation for vapor withdrawal systems is typi-
cally a two-step process. First, by reducing high tank
pressure to a lower line pressure with a first-stage regula
-
tor, then reducing line pressure to pressure required by
unit with a second-stage regulator. Both regulators and
associated system piping and valves need to be sized
correctly to provide generator with the required volume
and pressure of fuel at the generator connection point.
Fuel pressure from the primary regulator (supplied by
installing contractor) to generator's fuel shutoff valve
should be between 11–14 in water column (2.74–3.48
kPa). Always verify fuel pressure using the appropriate
specification sheet for the generator.
The piping system connecting outlet of the first-stage
regulator to the connection point on the second-stage
regulator must be correctly sized to provide fuel volume
required by unit at 100% load.
The piping system between outlet of second-stage regu-
lator and generator connection point must be sized to
provide fuel volume required by generator at 100% load,
while also staying within pressure range noted on the unit
specification sheet.
Follow regulator manufacturer's recommendation for
placement and mounting of the regulator.
Figure 4-2. Typical LP Gas Withdrawal Fuel System
Sediment Trap
A sediment trap must be installed downstream of the
generator fuel shutoff valve, and as close as practical to
the inlet of the generator. Sediment trap must be either a
tee fitting having a capped nipple installed vertically in the
lowest opening of tee fitting, or a device approved for use
as an effective sediment trap.
C
E
B
G
F
A
B
D
009330
A Fuel tank E Second stage regulator
B Manual fuel shutoff valve F Flexible fuel line
C First stage regulator with relief valve and pressure tap G Unit mounted regulator
D Sediment trap — —