Figure 4-11.-Fuel level control valve.
the main valve stem. It then shuts off the fuel
is a one-direction valve, It is important that the
pressure in the bottom side of the diaphragm. The
valve be installed so that the arrow points in the
pilot valve opens and permits fuel to drain from
desired direction of flow.
the main valve body. As the pressure on the under
In some turbojet engine fuel systems, there is
surface of the diaphragm is relieved, the main
a check valve between the fuel control and the fuel
valve opens to admit fuel from the auxiliary tank.
dump valve. The check valve remains closed until
a certain pressure is reached in the fuel line. A
bypass to the top of the dump valve transmits this
Check Valves.-- Check valves are installed in
the fuel system wherever fuel flow in one direc-
bypass pressure. Then, upon engine starting, the
tion is required. Fuel pressure in the direction of
controlled fuel pressure builds up. The dump
flow-indicated by an arrow on the valve-forces
valve is then actuated to close the drain port and
the valve open against spring pressure. Spring
open the flow into the fuel manifolds. The check
valve remains fully open during engine operation.
force and reversal of fuel flow close the valve. This
4-17
