Figure 5-16.—Gravity fueling nozzle.
smaller valve, and the nozzle is then completely
closed.
Never block the gravity fueling nozzle in an open
position. Ratcheted handles that allow the operator to
lock the handle in the open position are prohibited.
The nozzle must always be controlled by hand, so
that the flow of fuel may be instantly stopped when
necessary. A strainer or screen installed in the nozzle
provides a last means of stopping any dirt or foreign
matter from entering the aircraft fuel tanks. This
strainer should never be left out of the nozzle if it is
to be used for fueling aircraft.
DEFUEL PUMP
The defuel pump used in Cla-Val fueling stations
is the Blackmer rotary vane, positive displacement
pump. It is described in detail in chapter 4 of this
manual.
Flight and hangar deck station defuel pumps are
normally set to pump 100 gpm at 15 psi.
PORTABLE DEFUEL PUMPS
The portable defueling pumps are either an air-
motor-driven internal gear pump or an air twin-dia-
phragm pump mounted on a mobile cart. Both pumps
are operated off the ship’s low-pressure air system.
Three hoses are used with the defueling unit: an
air hose, which has a 1/2- or 3/4-inch inside diameter,
and two defueling hoses, which have 1 1/2 or 2 1/2-
inch inside diameter. One defueling hose is used as a
suction hose. It should be as long as necessary to
reach from the aircraft to the defueling unit. The
longer the hose, the less effective the defueling unit
is. The other defueling hose is used for the defueling
unit discharge hose. The length of this hose has little
effect on the defueling unit operation as long as it
does not become kinked.
The defueling suction hose is connected to the
aircraft in several different ways. For jet aircraft hav-
ing single-point fueling/defueling capability, the hose
is connected to the aircraft through a pressure
fueling nozzle. For aircraft drop tanks, the hose
without a fitting is inserted into the tank fill opening
or pushed up over a drain fitting on the bottom of the
tank. When defueling drop tanks only, the method
normally used
5-15
