Kohler Generator Sets 20--2800 kW User Manual download pdf (Page 40)

TP-5700 7/9328 Section 6 Fuel Systems

6.5 Auxiliary Fuel Pumps

Engine-driven fuel transfer pumps usually develop a

maximum of 7 psi (48 kPa) pressure and have a lift

capacity of 4-6 feet (1.2-1.8 m). Even if the engine pump

can draw fuel a greater distance, a more reliable system

results if a transfer tank and/or auxiliary pump are used

when the vertical lift exceeds three feet or fuel must be

drawn horizontally more than 20 feet (6.1 m).

On engines using less than ten gallons (38 L) of fuel per

hour (approximately 100 kW or less), an electric fuel

transfer pump powered by the engine starting battery

can be installed in series with the engine-driven transfer

pump. Best results are obtained when the electric pump

is located near the fuel tank rather than near the engine.

Where fuel must be lifted 6 feet (1.8 m) or more, or long

horizontal runs are involved, an electric motor driven

positive displacement pump should be used with a

transfer tank and float switch. The power supply for the

pump should always be from the load side of the transfer

switch for maximum reliability. Such pumps typically are

capable of lifting fuel 18 feet (5.5 m) or drawing it

horizontally up to 200 feet (61 m).

Where vertical or horizontal runs exceed these limits,

the pump should be remote mounted adjacent to the fuel

storage tank. When so located, these pumps can push

fuel over 1,000 feet (305 m) horizontally or more than

100 feet (30.5 m) vertically and deliver adequate fuel for

generator sets up to 2800 kW. Positive displacement

pumps should never be connected directly to an engine;

a transfer tank and float switch should always be used

so the engine fuel system is not subjected to excessive

fuel pressures.

A check valve or shutoff solenoid valve (wired into the

engine ignition) can be used to help keep the fuel line

primed. If such a valve is included in the system, it

should be installed on the outlet side of the auxiliary fuel

pump to minimize inlet restriction.

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Kohler Generator Sets 20--2800 kW User Manual Page 40