Detailed Theory; Fuel System - Aerotech BT 400-46 Installation And Operation Maintenance

Section 4
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4.11

Detailed Theory

4.12

Fuel System

4.13 Fuel Pump
4.14 The fuel pump is mounted on a bracket to the left of the engine. The pump is belt driven by the diesel
engine. The pump has three outlets (see figure 4-2). A primary by-pass will handle all the flow if the
balanced valve is closed. If the primary by-pass line is closed, the fuel will flow into the balanced valve
and hence out through both the nozzle fuel line and the secondary by-pass line. The secondary by-pass
supplies fuel to the diesel engine and returns surplus back to the fuel tank. The burner control valve, which
is in the primary by-pass line, is closed to obtained fuel flow to the nozzle. When this valve is open the
pump can not build up sufficient pressure to open the balanced valve and effect flow through the nozzle
fuel line. Closing the burner control valve allows the pump to build up pressure to the point where the
valve opens allowing fuel flow in the nozzle fuel line. The pressure at which the balanced valve opens is
determined by the compression of the piston spring, normally the spring is adjusted to 150 psi. This
pressure can be checked at the burner control valve. Since the pump delivers fuel in excess of the
maximum nozzle capacity there will always be flow through the secondary by-pass line when burner
control valve is on. Fuel from the secondary by-pass flows back into the tank through a check valve which
opens under a pressure of about 5 psi, which is sufficient to divert adequate fuel to the engine.
Figure 4-2 • Schematic Diagram of
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AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: 204-633-1999 (24 Hours) Fax: 204-694-1612 Email:
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Fuel Pump
10
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12.18.07 REVISION 1.02
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