shutdown. Residual lead and gum deposits from
The fuel-pressurizing and dump valve is
evaporated fuel cause problems in fuel manifolds
connected to the fuel manifold. It is composed
and fuel nozzles.
of an inlet check valve, a 200-mesh fuel inlet
In some instances, the function of draining
screen, a pressurizing or flow-dividing valve, and
fuel manifolds is accomplished by an individual
a manifold dump or drain valve.
unit known as a drip or dump valve. This type
Flow Divider
of valve may operate by pressure differential, or
it may be solenoid operated. See figure 4-18.
A flow divider performs essentially the same
The combustion chamber drain valve drains
function as a pressurizing valve. It is used, as the
raw fuel that accumulates in the combustion
name implies, to divide flow to the duplex fuel
nozzles. It is not unusual for units performing the
chamber. It drains after each shutdown when the
engine fire has gone out, and it drains fuel that
same functions to be called different names on
collects during a false start. The can type
different engines or by different manufacturers.
combustion chambers drain fuel, by gravity, down
Drain Valves
through the flame tubes or interconnector tubes
Drain valves drain residual fuel from the
until it gathers in the lower chambers. It is fitted
various parts of jet engines where accumulated
with drain lines to the drain valve. In the basket
annular type combustion chamber, the fuel drains
fuel is most likely to present operating problems
through the airholes in the liner and collects in
The chance of a fire hazard exits in a combustion
a trap in the bottom of the chamber housing. A
chamber if fuel accumulation occurs during
Figure 4-18.-Solenoid-operated drip (dump) valve.
4-24
