MIL-HDBK-1022
d) On the product pipeline or header just before the
line leaves a pumping station.
e) On the suction side and discharge side of each
pumping unit, except the suction side of vertical centrifugal
pumps installed in underground tanks.
f) At all aircraft fuel dispensing points.
g) On the inlet and outlet connection of each line
strainer, filter/separator, meter, automatic valve, and other
equipment that requires periodic servicing. One inlet valve
and one outlet valve may be used to isolate more than one
piece of adjacent equipment which are connected in series.
h) On the aboveground piping at each tank car or
tank truck off-loading connection. This requirement does not
apply to gravity off-loading lines unless block valves are
specifically called for on applicable drawings.
i) On the aboveground piping at each refueler
loading connection.
j) At critical points where pipes cross runways,
roads, and taxiways.
4.7.9.5
Valve Pits. Provide fiberglass or concrete pits
with a rolling or hinged cover designed in accordance with the
Air Force Standard Design AW 78-24-28 for all valves installed
in non-traffic areas on underground fuel systems.
4.7.10
Hydraulically Operated Diaphragm Control Valves.
Diaphragm-operated globe valves are used extensively in
fueling systems as control valves. These valves consist of a
main valve and a pilot control system. The valve is operated
by varying the amount of pressure above the diaphragm. Since
the chamber above the diaphragm exposes a greater area of the
diaphragm to chamber pressure than the area of the disc
exposed to line pressure, an equal pressure in the chamber and
pipeline results in a greater force being applied to the top
of the disc. This forces the disc against the seat, thus
closing the valve. By selecting the proper pilot control
system, these valves can be used in numerous ways to control
flow, pressure, and level within fueling systems.
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