are removed. The fuel then flows through the
second-stage filter elements, which further filters minute
particles and coalesces water particles to be collected in
and/or valve R to evacuate the 2-inch hose.
the filter sump. Coalescence is a process by which many
(6) Set engine throttle to maximum speed
small droplets of free water in the fuel are collected to
(2400 rpm) for a few seconds until evacuation is
form larger water drops. These large water drops are then
completed (meter stops turning backward).
released into the filter sump.
(7) Idle down engine. Close all valves. Stop
(2) Automatic Water Drain. When water in the
filter sump reaches a certain level, the water is
automatically ejected out of the filter sump. This is
(8) Store and cover fire extinguishers.
accomplished by an automatic drain valve connected to
the filter sump. The drain valve has a ball float which will
2-15. Filter/Separator Operation (M969, M969A1,
float in water but not in any type of fuel. Automatic water
M970, and M970A1)
drain for the M969 and M969A1 is different than for the
M970 and M970A1.
(a) As water accumulates in the filter sump
of the M969 and M969A1, a float rises. When the float
of the filter/separator on the M969, M969A1, M970, and
rises to a certain level, a valve will open in the automatic
M970A1, the engine and pump assembly provides filtered
drain valve, allowing pump pressure to be applied to a
fuel for various servicing operations. The filter/separator
diaphragm valve opening the automatic drain valve. Water
consists of an aluminum tank with 15 filter elements and 5
is then ejected out of the filter sump through the
second-stage water stripper elements. Fuel under
automatic drain valve. As water is being ejected, fuel flow
pressure from the pump enters the filter case inlet and
flows through the 15 filter elements, where solid particles
Figure 2-30. Filter/Separator Assembly (M969,
M969A1, M970, and M970A1).