Glossary of Compressed Air Terms :: G :: Glossary Index A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Gag A device attached to a safety or safety relief valve that prevents it from opening at the set pressure. Galling A form of wear in which seizing or tearing of the gear or bearing surface occurs. Gallon A unit of volume. A US gallon has 231 cubic inches or 3,785 liters. Gas A fluid (as hydrogen or air) that tends to expand indefinitely. Is one of three basic phases of matter. Gas bearings Are load carrying machine elements permitting some degree of motion in which the lubricant is air or some other gas. Gas bypass A portion of the discharge gas is redirected through a heat exchanger and then expanded back to suction pressure, where it is mixed with normal suction gas stream and commonly used to compensate for process flow demands. Gas compressor A machine that compresses gases. Divided into two groups; process gas compressors and oil and gas field compressors. Gas drying The drying of compressed gases other than air. Equipment size, choice of materials and other specifications may be decidedly different for drying gases other than air because of the specific properties of the gases. Properties include specific gravity, specific heat, viscosity, thermal conductivity, explosive characteristics, toxicity, corrosion and others. Gas laws The behavior of perfect gases, or mixtures thereof, follows a set of laws. Boyle' law, Charle's law, Amonton's law, Dalton's law, Amagat's law, Avogadro's law, Poisson's law. Gate valve A type of valve in which the closing element (the gate) is a disc that moves across the stream in a groove or slot for support against pressure. A gate valve has relatively large full ports and a straight line flow pattern. Very little pressure drop however subject to leakage if sealing surfaces are scored or marred or if debris becomes lodged in grove. Gauge An instrument for measuring, testing, or registering. Gauge pressure Is pressure as determined by most instruments and gauges. Glycol dehydration A method of drying natural gas. Governor A motor controller that regulates the air flow through an end plate into the motor to control the speed and power. A speed regulation device built into or attached externally. GPM Gallons per minute   Grade D breathable compressed air ANSI specification for a Compressed air supply source that meets OSHA specification # 1910.134(i)(1)(ii)requirements for breathing air.   Gravimetric efficiency The efficiency of the filter in removing some portion of a specified test contaminant under a specific set of laboratory conditions. It determines the mass of the contaminant the filter removes from a known sample introduced to the filter. Guide The portion of a valve used to guide the disc. Guide vane A stationary element that may be adjustable and which directs the flow medium to the inlet of an impeller. Glossary Index A B C D E F G H I J K L M N O P Q R S T U V W X Y Z