MIL-HDBK-1164
Foot Valve. A valve placed in the bottom of the suction pipe of a pump, which opens to
allow water to enter the suction pipe but closes to prevent water from passing out of it
at the bottom end.
Friction, Hydraulic. The resistance to flow exerted on the perimeter or contact surface
of a body of water moving in a stream of conduit, caused by the roughness that is
characteristic of the confining surface and which induces turbulence and consequent
loss of energy. Energy losses arising from excessive turbulence, impact at
obstructions, curves, eddies, and pronounced channel changes are not ordinarily
ascribed to hydraulic friction.
Friction Loss. Pressure lost in overcoming friction of pipe material on flowing water.
Gage. (1) A device for indicating magnitude or position in specific units, when such
magnitude or position undergoes change, for example: the elevation of a water surface,
the velocity of flowing water, the pressure of water, the amount of intensity of
precipitation, the depth of snowfall, etc. (2) The act or operation of registering or
measuring magnitude or position when characteristics are undergoing change. (3) The
operation, including both field and office work, of measuring the discharge of a stream
of water in a waterway.
Gage, Loss of Head. A gage on a filter which indicates the loss of head involved in the
filtering operation whereby the operator is able to ascertain the need for filter washing.
Gage, Pressure. A device for registering the pressure of solids, liquids, or gases. It
may be graduated to register pressure in any units desired.
Gage, Recording. A gage which makes a continuous record. Also called a register.
Gage, Water-Level. A gage, recording or otherwise, which indicates the water level in
a reservoir, still well, or other receptacle.
Gaging, Stream. Measuring the (1) velocity of a stream of water in a channel or open
conduit and the (2) area of the water cross section, for the purpose of determining the
discharge.
Gallery. (1) An underground structure designed and installed for the purpose of
collecting subsurface water. (2) A passageway in a structure, such as a dam water
treatment plant, etc., used for obtaining access to interior parts, or to carry pipes, or to
house machinery.
Galvanic Series. A list of metals arranged according to their relative corrosion
potentials in some specific environment; sea water is often used.
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