| Keyword | Description |
| Absolute Pressure | The normal component of force per unit area applied to a liquid or gas. Absolute pressure is the pressure measured above a perfect vacuum. |
| Air Trap | An inverted bucket trap equipped with scrubbing wire, prime and drain plugs. |
| Ammonia Trap | An inverted bucket trap equipped with a light-weight bucket, intended for service in an ammonia system. |
| AV | "Air Vent." See "Ball Float Vent", and "Thermostatic Air Vent". |
| Ball Float Vent | A ball float type device for venting air or other gases from above a liquid. |
| Bonnet | The upper part of a steam humidifier. |
| British Thermal Units (Btu) | The amount of energy required to raise the temperature of one pound of water one degree Fahrenheit – a unit of measure of heat energy. |
| BSPT | British Standard Taper Pipe Thread |
| BVSW | "Bucket Vent Scrub Wire." When used as part of a model designation, an inverted bucket air trap. |
| BW | Butt Weld – Connection type |
| Charpy Test | A test that measures the impact strength of a material; usually intended to detect embrittlement at low temperatures. |
| Companion Flange | A flange intended to mate with the flange on a trap, strainers, etc., and furnished as a loose part for the customer to attach to the piping system. |
| Condensate | The liquid left after latent heat has been removed from the gaseous phase of a liquid. |
| DG | "Dual Gravity." A liquid drainer equipped to drain a heavy liquid from under a lighter liquid. |
| Differential Pressure | The pressure difference across a trap or drainer, as determined by subtracting the pressure at the outlet from the pressure at the inlet. The differential pressure must be a positive quantity for the trap or drainer to work. |
| Dowtherm | A group of synthetic heat-transfer fluids. Dowtherm A, the type most commonly used in high-temperature applications, has a boiling point of 495 degrees Fahrenheit at atmospheric pressure. |
| Dowtherm Traps | A trap especially equipped to work with Dowtherm Fluids. Special features include a light-weight bucket, scrub wire, soft steel gasket, and a special inlet tube. |
| Enthalpy | The sum of internal energy and the product of pressure and volume – heat content. |
Entropy | The amount of energy in a system not available to do work. |
| Flange Facing | The design of a flange with respect to the gasketing surface. Examples: raised face, ring joint, tongue-and-groove, etc. |
| Flange Types | The design of a flange with respect to the method of attaching the flange to the trap, strainer, pipe, etc. Examples: weld neck, butt weld, slip-on, etc. |
| Flash Steam | Steam created when condensate at a higher pressure and temperature is released to a lower pressure and cannot exist as a liquid at the higher temperature. |
| F & T | "Float and Thermostatic Steam Trap." A mechanical trap that operates on the difference in density between steam and condensate as well as on the difference in temperature between steam and air. A lever connects a ball float to the discharge valve at the bottom of the trap. As condensate enters the trap the ball float rises, opening the discharge valve. The thermostatic valve in a F&T trap allows air in the trap to be discharged to the trap outlet, but closes when the hotter steam enters the trap. |
| Heat of Saturated Liquid | The amount of heat energy required to raise the temperature of a liquid from its freezing point to its boiling point. Measured in British Thermal Units per pound. |
| HLAR | A series of compound lever ball float air relief traps (air vents), without any compensating spring. |
| HLS | A series of compound lever ball float liquid drainers with a spring to partially offset the float weight. |
| Hydrostatic Test | A test in which the product is pressurized with water and checked for leakage. |
| IB | "Inverted Bucket Steam Trap" A mechanical trap which operates on the difference in the density between steam and condensate. The "bucket" is a cylinder, closed at the top. Steam entering the submerged bucket causes the bucket to float and close the discharge valve. Condensate entering the trap changes the bucket to a weight which sinks and opens the trap valve, discharging the condensate. The discharge valve on an IB is at the top of the trap. |
| Large Female | See "Flange Facings." |
| Large Male | See "Flange Facings." |
| Large Vent | An inverted bucket vent drilled out to a larger-than-normal size, to help pass large quantities of air. This term does not apply to vents enlarged to accommodate a scrubbing wire or vent wire. |
| Latent Heat | The amount of heat energy required to cause a change of phase of a liquid at its boiling point to a vapor. |
| LD | "Liquid Drainer." A ball float trap equipped to drain a liquid from under a gas. |
| Liquid Penetrant Inspection | A special test using a fluorescent liquid to detect surface cracks on a part. |
| Liquid Seal | An inverted bucket trap used in a refrigerant system as an expansion valve to pass liquid and hold back refrigerant gas. |
| Material Certification | A document listing the chemical and physical properties of various metallic components, normally in reference to a specific ASTM standard: (1) Actual material certificates may be traced directly to the components used in a particular item. (2) Typical material certificates reflect the typical properties of components used to manufacture a given item. Typical material certificates cannot be traced to a particular component or item. |
| Maximum Allowable Pressure | The maximum temperature for which the pressure-containing parts are rated, depending upon temperature. Abbreviated PMA. (Also MAP in present American usage.) |
| Maximum Allowable Temperature | The maximum temperature for which the pressure containing parts are rated, depending upon pressure. Abbreviated TMA. (Also MAT in present American usage.) Note that the maximum allowable pressure and temperature ratings are based on both conditions occurring together. Thus, a given product may have several different combinations of PMA and TMA applied to it. |
| Maximum Operating Pressure | The maximum pressure for which the internal mechanism of a trap is rated. Abbreviated PMO. (Also MOP in present American usage.) |
| Mechanism, Less Bucket | The internal mechanism of an inverted bucket trap, excluding the bucket. |
Mechanism, Less Float | A pressure-change assembly for an air vent or liquid drainer. |
| NPT | American National Standard Taper Pipe Thread |
| PCA | "Pressure Change Assembly." Also known as "mechanism less bucket." The internal mechanism of an inverted bucket trap, excluding the bucket. |
Pneumatic Test | A test in which the product is pressurized with air or nitrogen, submerged in water, and checked for leakage. |
Pounds Per Square Inch Absolute (psia) | Imperial units of measure for absolute pressure – 14.7 psi above gauge pressure. |
Pounds Per Square Inch Gauge (psig) | Imperial units of measure for gauge pressure. The pressure read on a standard pressure gauge – 14.7 below absolute pressure. |
Radiographic Inspection | An examination using x-rays or other types of radiation to detect flaws within a part. Not available for SW joints. |
| Restricted Orifice | A valve seat with a reduced diameter section downstream of the seating diameter, used to reduce the trap capacity to match very light loads. |
| RF | Raised face. See "Flange Facing." |
| RJ | Ring-joint facing. See "Flange Facing." |
| RTJ | Ring-joint facing. See "Flange Facing." |
Saturated Steam | The state in which steam contains only the amount of heat energy required to maintain the vapor state. Any loss of heat energy from saturated steam will cause it to begin condensing. (See Superheated Steam.) |
Saturated Vapor | See Saturated Steam. |
| Scrubbing Wire | A wire attached inside the cap passing through the bucket vent, intended to keep the bucket vent clean when operating on air or steam contaminated with oily or waxy residues. |
| Scrubble | A pad of stainless steel material, similar to a household scouring pad, used as a sound-absorbing medium in steam humidifiers. |
| Seismic Analysis | A stress calculation that includes the effects of external loading due to earthquake disturbance. |
Sensible Heat | See Heat of Saturated Liquid . |
| Sparge | To introduce air or gas into a liquid. |
| Specific Gravity (Liquid) | The ratio of the density of a given liquid to the density of water. |
| Specific Gravity (Gas) | The ratio of the density of a given gas to the density of air. |
| Stall Load | A condition in which heat transfer equipment is unable to drain condensate and becomes flooded due to insufficient system pressure. |
Steam | The gaseous phase of water above its boiling point. |
Steam Trap | An item to remove condensate, air and other gases from a steam system as quickly as they accumulate. There are many varieties, including Inverted Bucket, Float & Thermostatic, Disc, Thermostatic and Bimetallic. |
| Stress Analysis | A calculation of the significant stresses in a device at specified conditions of pressure and temperature. |
| Superheated Steam | Steam containing heat energy above the amount required to maintain the vapor state. Normally produced by adding potential waste heat from the boiler to saturated steam. |
SW | Socket Weld type connection. |
| T-Bucket | "Thermic Bucket." |
| Thermic Bucket | A bucket having a very large vent that is opened and closed by a bimetal element, intended to vent large quantities of air on start-up. |
| Thermostatic Air Vent | A device utilizing a thermostatic element to vent air from a steam space. |
Total Heat of the Steam | The sum of the Heat of Liquid and Latent Heat in Btu. |
| Trap With Scrubbing Wire | A standard steam trap equipped with a scrubbing wire, but no prime and drain plugs. |
| Vent Wire | A vent-cleaning wire that extends from the bottom of the trap upward through the bucket vent. |
| Water Hammer | A banging noise heard in a water pipe following an abrupt alteration of flow with resultant pressure surges. |
| Wiggle Wire | A small vent-cleaning device made of fine wire, which is retained in the bucket vent by loops on either end. Used when only moderate cleaning action is required. |
