MIL-HDBK-1022A
2.17.1
Piping Inlet Connections. Design connections to
tanks for reduced velocity and to prevent splashing by use of
diffusers. Fuel products are not permitted to free fall under
any circumstances. Position inlet as close to the tank floor
as possible to limit free fall.
2.17.2
Enclosed Vapor Spaces. Spaces above flammable or
combustible hydrocarbons in tanks or other liquid containers
must not have any pointed projection or probes which could be
focal points for static electricity discharges.
2.17.3
Filter/Separators and Fuel Quality Monitors. The
heaviest electrostatic charges are usually developed in
filtering elements of this equipment. The design should
attempt to reduce such charges before fuel is transferred into
storage tanks, vehicle tanks, or any equipment containing
vapor spaces.
a) By means of residence time in piping or in a
relaxation tank, provide 30 seconds relaxation time between
this equipment and discharging into a tank or vehicle. The
only fuel currently in the inventory that requires relaxation
time is JP-5.
b) Relaxation time is not required for projects
handling only fuels containing a static dissipated additive
that provides a conductivity level greater than 50
conductivity units (50 picosiemens per meter) at the fuel
temperature of the operations. Examples of this are JP-4 and
JP-8.
c) Prevent static build-up during filling of
filter/separators by providing a means to slow-fill the
vessels. Refer to Standard Design AW 78-24-28.
2.17.4
Aircraft Direct Fueling Stations. JP-5 requires a
30-second residence time in the piping or in a relaxation
tank before being discharged into the aircraft to allow
separate charges generated by the filtering elements to
recombine and neutralize themselves. Where possible, design
the piping layout to provide the required 30-second relaxation
time without use of a relaxation tank.
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