21 JANUARY 2003
falls with the liquid level.
Floating pan. A floating cover, usually of honeycomb design, which lays directly on the fuel in a
petroleum storage tank used to reduce vapor emissions and provide fire protection. Older pans
supported above the fuel using pontoons are not effective for fire prevention.
Fluid. A substance tending to flow or conform to the shape of a container. Fluid can be in a liquid or
Free water. Undissolved water content in fuel.
Freeze point. The temperature at which wax crystals form in distillate fuels and jet fuels.
Fuels control center (FCC). POL control center, usually manned twenty-four hours a day, 365 days a
Galvanizing. Zinc coating applied to iron or steel that cathodically protects it.
Gas. A fluid that has no particular shape or volume but tends to expand indefinitely. Will take the
shape of the container it is in and can be compressed.
Gasoline. A volatile liquid hydrocarbon fuel generally made from petroleum.
. A term used
to describe the equalizing
of static electrical potential between
or piece of equipment and the earth. This is done by connecting the equipment by wire to a ground rod.
Ground rod. A rod, typically 19 millimeters by 2.4 meters (0.75 inch by 8 feet), made of galvanized
steel, and driven into the earth for grounding. Copper ground rods are not typically used around
cathodic protection systems.
Hazardous atmosphere. An atmosphere presenting a potential for death, disablement, injury, or acute
illness from one or more of the following: flammable gas, vapor, or mist in excess of 10% of its LEL or
lower flammable limit (LFL); atmospheric oxygen concentration below 19.5% or above 23.5%; an
atmospheric concentration of any chemical substance greater than the occupational exposure limit
(OEL), which is capable of causing death, incapacitation, impairment of ability to self-rescue, injury, or
acute illness due to health affects.
Header. A term describing a loading/offloading connection or coupler.
Hot pit. An aircraft direct fueling system where aircraft can be refueled while engines are still running
Hydrant servicing vehicle - R-12. Vehicle used with a Type III hydrant system to refuel aircraft.
Hydrant system. Distribution and dispensing system for aviation fuels, consisting of a series of fixed-
flush-type outlets or hydrants connected by piping.
Hydraulic fluid. Fluids intended for use in hydraulic systems. Low viscosity, low rate of change of
viscosity with temperature, and low pour point are desirable characteristics.
. The science
at rest or in motion.
. Any components made
in various ratios.
. The science
at rest (see "Hydraulics").