GAGE PRESSURE - Absolute pressure minus atmospheric pressure.

GALVANIC ACTION - Wasting away of two unlike metals due to electrical current passing between them. The action is increased in the presence of moisture.

GALVANIC CELL - Electrolytic brought about by the difference in electric potential between two dissimilar metals.

GALVANIC COUPLE - The connection of two dissimilar metals in an electrolyte that results in current flow through the circuit.

GALVANIZING - The coating of metal with another by an electrolytic process; for example, electrolytically zinc-coat steel is called galvanized steel.

GAS - Usually a highly superheated vapor which, within acceptable limits of accuracy, satisfies the perfect gas laws.

GAS - Vapor phase or strata of a substance.

GAS CONSTANT - The coefficient "R" in the perfect gas equation: PV = MRT.

GAS LUBRICATION - A system of lubrication in which the shape and relative motion of the sliding surfaces cause the formation of a gas film having sufficient pressure to separate the surfaces.

GAS REFRIGERATION CYCLE - Where the refrigerant remains in the gaseous phase throughout.

GAS TURBINE - An engine in which gas , under pressure is formed by combustion, is directed against a series of turbine blades. The energy in the expanding gas is converted into rotary motion.

GAS TURBINE COMPRESSOR - a compressor designed foe the use with gas turbine installations. This could be centrifugal or an axial compressor.

GAS VALVE - Device in a pipeline for starting, stopping or regulating flow of gas.

GAS, INERT - A gas that neither experiences nor causes chemical reaction nor undergoes a change of state in a system or process; e.g., nitrogen or helium mixed with a volatile refrigerant.

GASIFICATION - When a substance is converted to become a gas.

GASKET - A device, usually made of a deformable material, that is used between two relatively static surfaces to prevent leakage.

GAUGE MANIFOLD - Chamber device constructed to hold both compound and high-pressure gauges. Valves control flow of fluids through.

GAUGE VACUUM - Instrument used to measure pressures below atmospheric pressure.

GENERAL CORROSION - Uniform overall corrosion of metal surfaces.

GENERATING TUBE - A boiler tube used for evaporation.

GENERATOR - A machine that changes that changes mechanical energy into electrical energy.

GFI, GFCI - Ground fault (circuit) interrupter - a device that senses ground faults and reacts by opening the circuit.

GOVERNOR SPEED DROOP -

GRAIN - A unit of weight; 0.0648 grams; 0.000143 pounds.

GRAIN BOUNDARIES - Referring to the junction of crystallites.

GRAINS OF MOISTURE - The unit of measurement of actual moisture contained in a sample of air. (7000 grains - one pound of water).

GRAINS PER GALLON - A unit of concentration. 1 gr/gal = 17.1 mg/L.

GRAM - A unit of weight; 15.432 grains; 0.0022 pounds.

GRAM-MILLIQUIVALENTS - The equivalent weight in grams, divided by 1000.

GRAVITY - The attraction exerted by the earth’s mass on objects at its surface.

GRAVITY, SPECIFIC - Density compared to density of standard material; reference usually to water or to air.

GREASE - A lubricant composed of an oil thickened with a soap or other thickener to a solid or semisolid consistency.

GREASE, BLOCK - A grease that is sufficiently hard to retain its shape in block or stick form.

GREASE, SODA BASED - A grease prepared from lubricating oil and sodium soap.

GREEN LIQUOR - The liquor resulting from dissolved molten smelt from Kraft recovery furnace in water.

GREENSAND - Naturally occurring materials, composed primarily of complex silicates, which possess ion-exchange properties.

GROOVING - A form of deterioration of boiler plate by a combination of localized corrosion and stress concentration.

GROUND - Zero voltage, or any point connected to the earth or "ground".

GROUND BED - Cathodic protection, an interconnected group of impressed-current anodes that absorbs the damage caused by generated electric current

GROUND BUS - A busbar in a panel or elsewhere, deliberately connected to ground.

GROUND COIL - Heat exchanger buried in the ground. May be used either as an evaporator or as a condenser.

GROUND CONDUCTOR - Conductor run in an electrical system, which is deliberately connected to the ground electrode. Purpose is to provide a ground point throughout the system. Insulation color green. Also called "green ground".

GROUND FAULT - An unintentional connection to ground.

GROUT - To force sealing material into a soil, sand or confined small space; or the sealing material used in grouting.