Gauge pressure plus barometric pressure. Absolute pressure can be zero only in a perfect vacuum.
A process involving controlled heating and subsequent controlled, generally slow, cooling applied usually to induce ductility in metals. The term also is used to cover treatments intended to remove internal stresses, alter mechanical or physical properties, produce a definite microstructure, and remove gases.
The temperature of the air, atmosphere or other fluid that completely surrounds the apparatus, equipment or the workpiece under consideration. For devices which do not generate heat, this temperature is the same as the temperature of the medium at the point of device location when the device is not present. For devices which do generate heat, this temperature is the temperature of the medium surrounding the device when the device is present and generating heat. Allowable ambient-temperature limits are based on the assumption that the device in question is not exposed to significant radiant-energy sources such as sunlight or heated surfaces.
American National Standards Institute - The coordinating organization for America's federated national standards system. The ANSI federation consists of nine hundred companies, large and small, and some two hundred trade, technical, professional, labor, and consumer organizations.
Pressure against which a fluid is flowing. May be composed of friction in pipes, restrictions in pipes, valves, pressure in vessels to which fluid is flowing, hydrostatic head, or other resistance to fluid flow.
A valve in which a pierced sphere rotates within the valve body to control the flow of fluids. The sphere may be trunnion mounted or free.
A barb is used to connect flexible hoses to pipes. One end has a stub with ridges that is inserted into the flexible hose to secure it.
Methane produced by the decomposition or processing of organic matter.
Valve used to blow pressure off the pipeline. Also used in purge.
In the industry, liquefied petroleum gas contained under moderate pressure in cylinders, sometimes referred to as bottles. Usually propane and/or butane.
British thermal unit
A traditional unit of energy equal to about 1.06 kilojoules. It is approximately the amount of energy needed to heat one pound of water one degree Fahrenheit
Btu per Cubic Foot
A measure of the heat available or released when one cubic foot of gas is burned.
Bulk Plants for LP Gas
A distributing point with permanently installed pressure tanks and required accessory equipment for storing large volumes of liquid petroleum gas and, in dealer's plants, withdrawing it for refilling bottles, delivery trucks, and trailers; in consumer's plants, withdrawing it for vaporization and utilization.
The maximum Btu per hour that can be released by a burner while burning with a stable flame and satisfactory combustion. Also called burner rating.
The portion of the burner beyond the outlet end of the mixer tube which contains the ports.
Method of hydrostatic testing plastic pipe by a uniformly increasing internal pressure so that the pipe fails in 60 to 70 seconds. See ASTM D 1599. Also called quick burst test.
A cup-shaped fitting placed on the end of a pipe to seal the pipe, usually threaded on the inside and screwed over the end of the pipe. Also, the act of placing a cap on a pipe. Also, to close off a gas or oil well.
A valve built to pass a fluid in one direction but to close automatically when the fluid tries to flow in the opposite direction. Compare VALVE, BACK PRESSURE.
Compressed Natural Gas (CNG)
Natural gas in high-pressure surface containers that is highly compressed (though not to the point of liquefaction). CNG is used extensively as a trans-portation fuel for automobiles, trucks and buses in some parts of Italy, New Zealand, and in Western Canada, and has recently begun to penetrate some regions of the United States. Small amounts of natural gas are also transported overland in high-pressure containers.
A self-contained, unvented, portable heater intended for temporary use during construction, sometimes called a salamander.
Corrugated Stainless Steel Tubing (CSST) Piping Sy
An assembly of corrugated stainless steel tubing, distribution manifold(s), tube connection fittings, and tube shielding devices, intended for field assembly and installation in residential or commercial buildings to distribute fuel gas to gas utilization equipment within the building. The piping system may also include a gas pressure regulator(s), a shutoff valve(s), and other approved devices or components.
A coupling connects two pipes to each other. If the material and size of the pipe are not the same, the fitting may be called a 'reducing coupling' or reducer, or an adapter. The term 'expander' is not used for a coupler that increases pipe size; instead 'reducer' is used.
A cross has one inlet and three outlets, or vice versa. Crosses are common in fire sprinkler systems, but not in plumbing due to their extra cost as compared to using two tees. The three outlets should be named in order; left, middle , right. For example 15-22-15
The most common unit of measurement of gas volume. It is the amount of gas required to fill a volume of one cubic foot under stated conditions of temperature, pressure, and water vapor.
A membrane separating two different pressure areas within a control valve or regulator.
A heating unit in which the combustion products are mixed with the air or liquid being heated. Compare INDIRECT-FIRED.
A container or segment of piping placed at a low point in a system to collect condensate, dust, and foreign material, enabling their removal. Also known as Drip Leg and Drip Pot. Compare SERVICE DRIP.
A pipe fitting installed between two lengths of pipe or tube allowing a change of direction, usually 90° or 45°. The ends may be machined for butt welding, threaded (usually female), or socketed, etc. When the two ends differ in size, it is called a reducing or reducer elbow.
A metallic or plastic component used in joining lengths of pipe into various piping systems; includes couplings, ells, tees, crosses, reducers, unions, caps, and plugs.
A type of compression fitting used with metal tubing, usually soft steel and ductile (soft) copper, though other materials are also used. Tube flaring is considered to be a type a forging operation, and is usually a cold working procedure. During assembly, a flare nut is used to secure the flared tubing's tapered end to the also tapered fitting, producing a pressure-resistant, leak-tight seal. Flared connections offer a high degree of long-term reliability and for this reason are often used in mission-critical and inaccessible locations. The most common flare fitting standards in use today are the 45 degree SAE style, and the 37 degree AN style, also used with the JIC system. The AN/JIC style generally has a higher pressure rating for a given size tubing. SAE and AN/JIC fittings are completely incompatible due to the different flare angle.
The lowest temperature at which the vapors arising from a liquid surface can be ignited by an open flame.
A flexible tubing connecting a rigid pipe gas supply line to gas utilizing equipment.
Gas Appliance Manufacturers Association
The section of a gas-turbine that provides the high temperature gases needed to drive the power turbine.
Cooking stove. GAMA lists the following types: (1) Free-standing; (2) Set-in; (3) High Oven; (4) Built-in, Commercial; (5) Luncheonette and Restaurant; (6) Heavy Duty (Quality, Battery Type).
Gas, Liquefied Petroleum (LPG)
A gas containing certain specific hydrocarbons which are gaseous under normal atmospheric conditions but can be liquefied under moderate pressure at normal temperatures. Propane and butane are the principal examples.
A naturally occurring mixture of hydrocarbon and nonhydrocarbon gases found in porous geologic formations beneath the earth's surface, often in association with petroleum. The principal constituent is methane. 1. Dry. Gas whose water content has been reduced by a dehydration process. Gas containing little or no hydrocarbons commercially recoverable as liquid product. Specified small quantities of liquids are permitted by varying statutory definitions in certain states. 2.Liquefied (LNG). See LIQUEFIED NATURAL GAS. 3. Sour. Gas found in its natural state, containing such amounts of compounds of sulfur as to make it impractical to use, without purifying, because of its corrosive effect on piping and equipment. 4.Sweet. Gas found in its natural state, containing such small amounts of compounds of sulfur that it can be used without purifying, with no deleterious effect on piping and equipment. 5. Wet. Wet natural gas is unprocessed natural gas or partially processed natural gas produced from strata containing condensable hydrocarbons. The term is subject to varying legal definitions as specified by certain state statutes. (The usual maximum allowable is 7lbs./MMcf water content and .02 gallons/Mcf of Natural Gasoline.)
The connection of branch piping to an operating line, and the tapping of the operating line while it is under pressure.
Refers to the internal diameter of a hose, tube or pipe.
Inch of Mercury
A pressure unit representing the pressure required to support a column of mercury one inch high at a specified temperature; 2.036 inches of mercury (at 32 degrees F and standard gravity of 32.174 ft/sec2) is equal to a gauge pressure of one pound per square inch.
Inch of Water
A pressure unit representing the pressure required to support a column of water one inch high. Usually reported as inches W.C. (water column) at a specified temperature; 27.707 inches of water (at 60o and standard gravity of 32.174 ft/sec2) is equal to a gauge pressure of one pound per square inch.
A heater in which combustion products do not come in contact with the material to be heated; heating of the material is accomplished by radiation or conduction from the heated surfaced. Compare DIRECT-FIRED.
A self-contained, vented, or unvented heater used to convert the combustion energy to radiant energy, a substantial portion of which is in the infra-red spectrum, for the purpose of direct heat transfer.
The location at which two pieces of pipe or a pipe and a fitting are connected together.
A unit of electrical work equivalent to 1,000 watts, 1.3414 horsepower, or .9478 Btu/sec. (See ELECTRIC ENERGY).
Liquefied Natural Gas (LNG)
Natural gas which has been liquefied by reducing its temperature to minus 260 degrees Fahrenheit at atmospheric pressure. It remains a liquid at -116 degrees Fahrenheit and 673 psig. In volume, it occupies 1/600 of that of the vapor at standard conditions.
Liquefied Petroleum Gas (LPG)
A gas containing certain specific hydrocarbons which are gaseous under normal atmospheric conditions, but can be liquefied under moderate pressure at normal temperatures. Propane and butane are the principal examples.
The amount of gas delivered or required at any specified point or points on a system; load originates primarily at the gas consuming equipment of the customers. Also, to load a pressure regulator is to set the regulator to maintain a given pressure as the rate of gas flow through the regulator varies. Compare DEMAND.
The conduit of an appliance which supplies gas to the individual burners. Also, a pipe to which two or more outlet pipes are connected.
National Fuel Gas Code
A code that provides general criteria for the installation and operation of gas piping and gas equipment on consumers' premises. The code is sponsored by both the National Fire Protection Association (NFPA-54) and the American National Standards Institute (ANSI Z223.1).
National Pipe Thread (NPT)
A U.S. standard for tapered threads used to join pipes and fittings. ANSI/ASME standard B1.20.1 covers threads of 60-degree form with flat crests and roots in sizes from 1/16 inch to 24 inch Nominal Pipe Size [NPS] (this standard also covers various parallel ('straight') threads, see ). The taper rate for all NPT threads is 1?16 (¾ inch per foot) measured by the change of diameter (of the pipe thread) over distance. The taper divided by a center line yields an angle 1° 47' 24" or 1.7899° as measured from the center axis. Commonly-used sizes are ?, ¼, ?, ½, ¾, 1, 1¼, 1½, and 2 inch, appearing on pipe and fittings by most U.S. suppliers. Smaller sizes than those listed are occasionally used for compressed air. Larger sizes are used less frequently because other methods of joining are more practical at 3 inches and above in most applications.
Natural Gas Vehicle (NGV)
A vehicle that is equipped to operate using natural gas, either as the sole fuel (a dedicated NGV) or as an option (a dual-fuel NGV).
A small valve that is opened and closed to permit or restrict fluid or gas flow by the movement of a pointed plug or needle in an orifice or tapered orifice in the valve body.
The opening in an orifice cap, orifice spud, or other device whereby the flow of gas is limited and through which the gas is discharged.
A small flame which is utilized to ignite the gas at the main burner(s).
All parts of those physical facilities through which gas is moved in transportation, including pipe, valves, and other appurtenances attached to pipe, compressor units, metering stations, regulator stations, delivery stations, holders, and fabricated assemblies. See SYSTEM TYPE.
A conduit for fluids and gases consisting of pipe or tubing with all necessary valves and fittings. a.Pipe. Refers to rigid conduit of iron, steel, copper, plastic, or brass. b.Tubing. Refers to a semi-rigid conduit of steel, copper, plastic, brass, or aluminum.
Same as plastic pipe except that it is usually of small diameter and sized on the same system commonly used for copper tubing.
An external thread pipe fitting that is inserted into the open end of an internal thread pipe fitting to seal the end of a pipe. Also, sealing a hole in a vessel, such as a pipe or tank, by inserting material in the hole and then securing it. Also refers to the material used to plug the hole.
Opening in the seat of a slide valve in diaphragm gas meters or an opening in any equipment for the flow of gases or vapors.
The loss in static pressure of the fluid (air, gas, or water) due to friction or obstruction in pipe, valves, fittings, regulators, burners, appliances, and breeching. See PRESSURE LOSSES.
Instrument for measuring the relative pressure of a fluid. Types include gauge, absolute, and differential.
The estimated maximum pressure that the medium in the pipe can exert continuously with a high degree of certainty that failure of the pipe will not occur.
The pressure due to the weight of the atmosphere (air and water vapor) on the earth's surface. The average atmospheric pressure at sea level (for scientific purposes) has been defined at 14.696 pounds per square inch absolute.
Pressure, Gauge (PSIG)
Pounds per square inch above atmospheric pressure.
A gas, the molecule of which is composed of three carbon and eight hydrogen atoms. Propane is present in most natural gas and is the first product refined from crude petroleum. It has many industrial uses and may be used for heating and lighting. Contains approximately 2,500 Btu per cubic foot.
Pounds per square inch
The act of replacing the atmosphere within a container by an inert substance in such a manner as to prevent the formation of explosive mixtures.
A device that maintains the pressure in a fluid flow line, less than its inlet pressure within a constant band of pressures, regardless of the rate of flow in the line or the change in upstream pressure.
Safety Shutoff Device
A device that will shut off the gas supply to the controlled burner(s) in the event the source of ignition fails. This device may interrupt the flow of gas to the main burner(s) only or to the pilot(s) and main burner(s) under its supervision.
A type of construction heater.
Standard Cubic Feet Per Hour. This is a common way to measure the flow of gas with a flow meter.
A pipe size system (outside diameters and wall thickness) originated by the iron pipe industry.
An automatic valve that is opened or closed by an electromagnet.
The volume of a unit weight of a substance at specific temperature and pressure conditions.
An L-shaped pipe fitting with external threads on one end and internal threads on the other end. Compare ELL.
A tee with an external thread on one of the run connections and with internal threads on the opposite run connection and on the side outlet.
To cut threads in a round hole so that other fittings or equipment can be screwed into the hole. Also to make an opening in a vessel or pipe.
The tensile stress necessary to cause failure in a short-time test. It is performed by pulling a specimen of specified dimension at a specified rate.
A unit of heating value equivalent to 100,000 British thermal units (Btu).
Two pieces of dissimilar metal welded or brazed together at one end. When the welded end is at a different temperature from the free ends, an electrical voltage is developed that can be measured across the free ends, and that is proportional to the temperature difference and can, therefore, be used to measure the temperature at the brazed end.
A quality which allows a material to repeatedly soften when heated and harden when cooled. Typical of the thermoplastics family are the styrene polymers and copolymers, acrylics, cellulosics, polyethylenes, vinyls, nylons, and the various fluorocarbon materials.
Two-PSIG Gas Piping System
A gas piping system that utilizes 2-psig pressure downstream of the point of delivery. This type of gas piping system allows greater versatility in the design of branch systems and in a multi-family building that could reduce the cost of installing the piping system when compared to the traditional 1/4 psig system
A threaded fitting used to couple two runs of pipe together without having to turn or dismantle either run of pipe.
From a reference point, any point located nearer the origin of flow, that is, before the reference point is reached.
A mechanical device for controlling the flow of fluids and gases; types such as gate, ball, globe, needle, and plug valves are used.
A tube tapered down to a lesser diameter and then expanding gradually to its original diameter. Pressure-measuring taps are provided at the entrance and at the constricted throat for determining pressure differential through the tube used for metering.
Specified wall thickness of pipe without adding an allowance to compensate for the underthickness tolerances permitted in approved specifications.