GALLOWAY BOILER -- A cylindrical boiler of the
Lancashire type, in which the two furnace tubes unite, at a short distance from
the grates, into a single arched oval flue, crossed by water tubes.
GALLOWAY TUBES --The inclined water tubes which cross the flue
of a Galloway boiler to assist circulation and increase the heating
surface.
GALVANIC CORROSION -- Accelerated corrosion of a metal because
of an electrical contact with a more noble metal or nonmetallic conductor in a
corrosive electrolyte.
GASOHOL -- A blend of finished motor gasoline containing
alcohol (generally ethanol but sometimes methanol) at a concentration between
5.7 percent and 10 percent by volume.
GAS OIL -- European and Asian designation for No. 2 diesel
fuel.
GAS TIP -- The part of a burner that discharges the gas fuel
via one or more openings into the furnace.
GATE VALVE -- A stop valve using the wedge-and-double-seat
principle. It may be used to control fluids containing some solids, for when
wide open, it operates on a straight-through flow.
GAUGE GLASS -- The glass tube, or pair of flat glass plates,
fitted to a water-gauge to provide a visual indication of the water-level in a
boiler or a tank.
GAUGE COCKS -- Small test cocks fitted to the side of a vessel
to ascertain the liquid level therein, as on many steam boilers.
GAUGE PRESSURE -- Of a fluid, the pressure as shown by a
pressure gauge, i.e., the amount by which the pressure exceeds the atmospheric
pressure, the sum of the two giving absolute pressure.
GEAR PUMP -- A small pump consisting of a pair of gear-wheels
in mesh, enclosed in a casing, the fluid being carried round from the suction
to delivery side in the tooth spaces; used for lubrication systems, etc.
GENERATING STATION -- A power plant.
GIRDER -- A beam, usually steel, to bridge an open space.
Girders may be rolled sections, build up from plates, or of lattice
construction
GLOBE VALVE -- A stop valve using the round-disk-and-seat
principle. Used where the fluid controlled is comparatively clean.
GRADE -- Oil classification according to quality, generally
based on ASTM specifications.
GRATE -- That part of a furnace which supports the fuel. It
consists of fire bars or bricks so spaced as to admit the necessary air.
GRAVITY HEATING SYSTEM -- A system in which the heating medium
circulates naturally because of the temperature difference between the supply
and return medium.
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