Pumping units and filter/separators are widely used throughout the theater. Pumping units serve as a
primary means for the receipt, storage, and issue of petroleum fuels during bulk and retail Class III
operations. Filter/separators provide an effective means for insuring that fuels are free from contamination.
As an NCO there are several assignments that require knowledge of maintaining this equipment.
PART A - USE OF FILTER/SEPARATORS
Filter/separators (Figure 2-1, and 2-2) remove solid contaminants and entrained water from liquid fuels.
Filter/separators range in size from 15-GPM to 600-GPM capacity. Organizational maintenance personnel
are responsible (with the help of the equipment operators) for replacing the filter elements in all
filter/separators. The use of standard interchangeable elements and canisters make it simple to replace
elements in filter/separators. They may be used when ground product, such as automotive gasoline and
diesel fuel, are pumped to the user's vehicles. They must be used on all lines pumping fuel directly to
aircraft and to vehicles that refuel aircraft. In addition, all fuel loaded into aircraft refueling vehicles should
be filtered again before it is pumped to aircraft.
The standard filter element fits inside the canister. It is a perforated tube surrounded by a fiberglass
filtering material, which in turn is wrapped with several layers of different material. The fiberglass material
filters solid particles from fuel. The cotton knit and fiberglass screen and combine fine particles of water in
fuel to form water droplets which settle because they are heavier than fuel. The expected service life of the
standard filter element is 24 months.
The canister is a cylinder approximately 5 inches in diameter and 23 inches long. It consists of an outer
and inner-tube. The inner tube is made of perforated metal and metal screen. The outer tube is made of
perforated metal lined with a Teflon coated screen.
Raw fuel enters the center tube of the filter element through a fitting at the bottom of the canister. Solid
filtering material. As the fuel passes through the outer layers of the element, fine particles of water in the
fuel are coalesced into droplets. The fuel containing the coalesced water passes through the inner tube of
the canister to the space between the inner and outer tubes. The Teflon coated screen of the outer tube
throws off water droplets, and they fall to the bottom chamber of the filter separator. Only clean fuel passes
through the outer canister tube into the filter separator tank. Tank vehicles such as the M131A5C tank
semitrailer have filter/separators that work in three stages. The first stage has 15 filter elements that remove
solid contaminants. The second stage has five canisters to separate water from fuel and let water drain into
the sump. The third stage has 15 go/no go fuses. They shut off the flow of fuel if the other two stages allow
water or contaminants to exceed a safe level. M49AC filter/separators have three filter elements, three
separator canisters, and three go/no go fuses. The go/no go fuses automatically shut off the flow of fuel if
the water and/or contaminants reach a high level.
Performing Before Operational Maintenance.
Make a visual check for leaks and for loose or missing parts in cover assembly and other connections.
Ensure that all valves operate freely and do not leak. Ensure drain valves are in closed position.
Ensure the ground wire is connected properly and is not broken.
Ensure gaskets are in place and not leaking.
Ensure a fire extinguisher is easily accessible and in working order.
Performing During Operational Maintenance.
Check the pressure gage reading to ensure pressure reading is below the red band on the gage. If it is in
the yellow band change elements after the operation. (If in the red stop operation).
Check the water level sight gage and drain the water if necessary.
Check the filter separator for leaks.