Society of Automotive Engineers.

A device that limits fluid (liquid and gaseous) pressures by discharging some of the pressurized liquid or gas.

An automatic pressure relieving device actuated by the static pressure upstream of the device, which opens in proportion to the increase in pressure over the opening pressure.

One in which the space occupied by the mixture is saturated with water vapor at the mixture temperature.

The pressure existing at a given temperature in a closed vessel containing a liquid and the vapor from that liquid after equilibrium conditions have been reached. It is dependent only on temperature and must be determined experimentally.

Occurs when the vapor is at the dew point or saturation temperature corresponding to its partial pressure. A gas in never saturated with a vapor. However, the space occupied jointly by the gas and vapor may be saturated.

A coating or precipitate deposited on surfaces such as water pipes or steam boilers that are in contact with hard water. Water that contains carbonates or bicarbonates of calcium or magnesium are likely to cause scale when heated.

Standard cubic feet per minute (SCFM or scfm); a flow of free air measured at some reference point and converted to a standard set of reference conditions (e.g., 14.4 psia, 80° F, and 60% relative humidity.)  SDFM means cfm at standard conditions; however, standards vary and some care is necessary.  In the USA, the usual standard is 14.696 psiA and 60°F. Some chemical engineers will use one ATA and 0°C, but usually will be specific about the reference point.  Europeans normally use one ATA and 0°C.  It is not the same to all people; therefore, it is best to specify the reference pressure and temperature.

A positive displacement rotary compressor.

Self Contained Underwater Breathing Apparatus.

The average level of the ocean over the entire earth with tidal fluctuations taken into account.

Devices used between rotating and stationary parts to separate and minimized leakage between areas of unequal pressures.

The stationary seating surface, the inlet of a valve.

Heat cannot, of itself, pass from a colder to a hotter body.
 

The order in which compressors are brought online.

The gauge pressure at which a safety valve visibly and audibly opens or at setting which a relief valve discharges an unbroken stream of liquid.

The part of the rotating element on which the rotating parts are mounted and by means of which energy is transmitted from the prime mover; with compressors, to the air or gas being compressed.

The power required at the compressor drive shaft. Losses in external transmissions such as gears and belt drives are not included.

Devices that may be used to position the impeller or to protect the shaft.

The dimensionless number obtained when the difference between maximum and minimum instantaneous shaft speeds during one period is divided by the arithmetic mean of these two.

A group of instruments used only to check the calibration of field instruments.

The international system of unit measurement.

A device fitted at a valve's outlet to reduce and dampen the noise produced when the valve vents.

A desiccant most commonly used in heat regenerative type dryers.

A piston that only compresses air with its stroke in one direction.

Machines in which air or gas is compressed in each cylinder or casing from initial intake pressure to final discharge pressure.

Compressors having only one impeller.
 

Any paint gun which uses air flowing over an opening to create a vacuum to draw paint up a tube to be atomized.

A type of journal bearing in centrifugal air compressors.

The internal leakage within a rotary compressor. It represents gas at least partially compressed but not delivered. It is experimentally determined and expressed in CFM to be deducted from the displacement to obtain capacity.

The speed required of a rotary compressor to maintain a given discharge pressure, supplying leakage only (zero actual output). It is an experience factor.

A soft, black, mayonnaise-like deposit which is typically an emulsion of oil, water, and oil insolubles.

An air operated device for hoisting or pulling similar to a winch.

A safety relief valve which works backwards and is used in vacuum systems. Instead of venting compressed air out of the system like a normal safety relief valve, it lifts at a pre-set vacuum to allow air into the system thereby protecting the vacuum pump.

A metallic pad, usually embedded in concrete, on which the compressor feet are mounted.

The point (speed of sound) at which air flow through an orifice can not increase regardless of pressure drop.

Standard operating procedures for the production, purification, storage and distribution of compressed breathing air.

Specific Power Consumption.

High purity gaseous chemicals used as lab gases as well as intermediates in production processes. Generally defined as a packaged gas in smaller form from a 10-cubic-foot hand-held lecture bottle to a 21,000-pound tube trailer, but are usually sold in cylinder quantities; value-added products of a higher purity which can be sophisticated, technology-driven mixtures.

The shaft input per unit of compressor capacity.
 

The ratio of fuel consumption to compressor capacity.
 

The ratio of the specific weight of air or gas to that of dry air at the same pressure and temperature.

The quantity of heat required to raise the temperature of a unit weight of a substance by one degree.

The weight of water vapor in an air-vapor mixture per pound of dry air.
 

A measure of air compressor efficiency, usually in the form of bhp/100 acfm or acfm/bhp.

The volume of a given weight of gas, usually expressed as cu ft/lb as SPT conditions.

This property of a gas is the weight of air or gas per unit volume. Unless specified, it refers in compressor practice to the weight per unit volume at conditions of total temperature, total pressure and composition which prevail at the compressor intake.

The number of revolutions per minute (rpm) of the compressor shaft.
 

The rate at which sound waves travel; approximately 750 MPH.

The rod connecting the disc to the lever on a valve.

Screw compressor development center; the licensor to 90% of twin screw compressor market.

Stability is 100 minus the surge limit at rated discharge pressure, where the surge limit is expressed in percentage of rated capacity.

The interaction between the stages of a centrifugal compressor. When a multi-stage compressor is designed, each stage can operate at only one point of its characteristic curve. The point is determine by the design conditions of temperature, flow, and pressure. As the design conditions change the point on the stage characteristic curve will shift. The interaction of each stage curve is referred to as the "stack up" of the compressor.

Steps in the compression of a gas, In reciprocating compressors, each stage usually requires a separate cylinder, in dynamic compressors, each requires a separate rotor disc.

Air at 68 °F, 14.70 psia, and relative humidity of 36 % (0.0750 density) (as per A.S.M.E., however, in the gas industry, the temperature of standard air is usually given as 60 °F. unless specifically stated otherwise.

Flow of free air measured and converted to a standard set of reference conditions (14.5 psia, 68oF, and 0% relative humidity).

A measure of compressed air and refers to that quantity of dry air (0% RH) which in gaseous form would occupy a volume of one cubic foot at 60 °F and 14.70 psi absolute pressure.

A system in which air supply is matched to demand by the starting and stopping of the unit.

The condition of a system (or part thereof) at an instant of time as described or measured by its properties.

The rod connecting the disc to the lever on a valve.

Free from living organisms and especially micro-organisms. Usually used in food and dairy applications.

The unstable operation of a centrifugal compressor below the design point of the compressor.

Standard pressure and temperature.

A device used to separate air solids from the stream of air that might become a source of trouble. Adulterants caught in the strainer are blown out through an orifice fitted with a valve or plug. The strainer should be opened periodically for a thorough cleaning.

The difference between the maximum extended height and the compressed height of an air actuator.

That part of the total stroke which can be utilized repeatedly in actuator applications. It is measured starting at the compressed height and is the difference between the compressed height and the actuator height limit.

The connections between the headers and the work station.

The pressure found on the suction side of a refrigeration system.

A factor expressing deviation of a gas from perfect gas laws.
 

Filtration that occurs at the surface layer (as opposed to within the body depth) of the filter, and is accomplished by passing the material to be filtered over a grating, screen, sieve or membrane fabric with micro sized holes. The size of the holes in the filter determines what materials will pass through and which materials will be retained by the filter.

The reversal of flow within a dynamic compressor that takes place when the capacity being handled is reduced to a point where insufficient pressure is being generated to maintain flow. Also known as pumping.

In a dynamic compressor, surge limit is the capacity below which the compressor operation becomes unstable.

A term primarily used by firms who sell small compressors, because it makes their compressors appear larger than they really are. The swept volume is the actual displacement of the piston, forgetting such losses as bumping clearances, valve clearances, ring losses, etc.  It's not unusual to see an advertisement offering a compressor with a delivery of 30 cfm, swept.  In reality the compressor will only deliver approximately 20 scfm.

A hydrogen and carbon monoxide mixture.

A lubricating oil made with synthetic base stocks.

[Home] [About Us] [Audit Final Reports] [Calculators] [Conversion Factors] [Contact Us] [Customer References] [Experience Summary] [Glossary] [Site Map] [Technical Papers]

Web Site Designed/Developed by
S & P Custom, Inc