Pnomatik Sözlüğü

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A&I
ACRONYM - Assembly and Installation

A&R
ACRONYM - Automation and Robotics

Absolute efficiency
An arbitrary filter efficiency rating.
Absolute micron rating
All (not just 98%) particles larger than the stated micron size have been removed from the fluid being filtered.
Absolute pressure
The total pressure measured from absolute zero ( i.e., from an absolute vacuum).
Absolute temperature
The temperature of a body referred to the absolute zero, at which point the volume of an ideal gas theoretically becomes zero. (Fahrenheit scale is minus 459.67°F / Celsius scale is minus 273.15°C).
Absolute viscosity ( Dynamic )
Is the force in newton required to move a fluid layer of one square meter area and a thickness of one meter with a velocity of one meter per second.
Absorb
A method to trap liquids or gases by causing them to penetrate into the absorbent material.
AC
ACRONYM - An electrical current that periodically reverses its direction. Standard in US and Canada is 60 cycles per second. Europe and other countries is 50 cycles per second. Alternating current
Acidity
The quality, state or degree of being acid. In oils, acidity denotes the presence of acid-type constituents whose concentration is usually defined in terms of neutralization number.
ACFM
ACRONYM - Actual cubic feet per minute.


ACT
ACRONYM - Activate, Activation

Activated alumina
An adsorption type desiccant.
ACTR
ACRONYM - Actuator

Actual capacity
Quantity of gas actually compressed and delivered to the discharge system at rated speed of the machine and under rated pressure conditions.
Adiabatic compression
A type of compression where no heat is transferred to or from the gas during the compression process.
Adiabatic efficiency
Ratio between measured shaft power and the adiabatic compression power, referring to measured mass flow.

Adsorb
A method causing a liquid or gas to condense on the surface only of an adsorbing material.
Adsorbent filter
a filter medium primarily intended to hold soluble and insoluble contaminants on its surface by molecular adhesion.
Adsorptive filtration
the attraction to, and retention of particles in, a filter medium by electrostatic forces, or by molecular attraction between the particles and the medium.
Aeration
To combine or charge with gas.
Aerosol
A suspension of fine solid or liquid particles in a gas.
Aftercooler
Heat exchangers for cooling air or gas discharge from compressors. Designed to reduce the temperature and liquefy condensate vapors. Both air cooled and water cooled units are available.
Aftercooling
The removal of heat from a gas after compression is completed.
Air
A colorless, odorless, tasteless gas. A mixture of individual gases. The gaseous mixture surrounding the earth. Standard density of dry air free of carbon dioxide (0°C, 101,325 kPa) is equal to 1,292 8 g/L. Standard conditions for air in spectroscopy are 101,325 kPa, 15°C, 0,03 % CO2, dry.
Air actuator
An elastomeric bellow with specially designed metal end closures used in place of pneumatic or hydraulic cylinders. A device which induces action or motion with compressed air being the medium through which the power is transmitted.
Air amplifier
A component on a compressed air line designed to increase in magnitude the flow by releasing small amounts of compressed air at high velocity through an internal, ring shaped nozzle. This column of air released through the front creates a vacuum behind, thus pulling ambient air through the rear and pushing ambient air in front.
Air borne
Supported or transported by air.
Air brush
a device for applying a fine spray by compressed air.
Air bubble technique
When compressed air is forced through a submerged perforated hose or pipe. Some applications include; ice prevention, reduction of salt intrusion, underwater basting, pneumatic breakwaters and general mixing and agitation
Air cooled compressor
A compressor cooled by atmospheric air circulated around the cylinders or casing.
Air curtain
A component on a compressed air line that provides wide are coverage with a thin sheet of air. Also amplifies compressed air flow, reduces noise. Used in blowing, cooling. Also known as air knife.
Air cylinder
A component made up of a cylinder barrel, end covers, a piston rod, a steel or stainless steel piston. A device which induces action or motion with compressed air being the medium through which the power is transmitted.
Air dryer
A device for drying compressed air by means of condensation obtained by over-compression or cooling, absorption, adsorption or a combination of the above methods.
Air flow
The motion of air relative to a body in it.
Air knife
A component on a compressed air line that provides wide are coverage with a thin sheet of air. Also amplifies compressed air flow, reduces noise. Used in blowing, cooling. Also known as air curtain.
Air leak
A crack or hole that accidentally admits a gas or lets it escape.

Air lock
device that permits passage between regions of differing air pressures, most often used for passage between atmospheric pressure and chambers in which the air is compressed. A typical modern air lock consists of a cylinder of steel plate with airtight doors located at both ends, one opening from the outside into the lock, the other from the lock into the compressed-air chamber, together with valves to admit or to exhaust compressed air. One of the doors must always be closed; before the other is opened, the pressure within the air lock must be equalized with that on the opposite side.

Air motor
Is a compact, low mass unit giving smooth, non-vibrating power. Several types include vane, piston, percussion and turbine type motors
Air nozzle
A projecting aperture at the end of a tube, pipe etc. serving as an outlet for compressed air. Reduces the demand on the compressor by generating the highest thrust and volume for the lowest possible air consumption.
Air preheater
Indirect heat exchanger designed to transfer heat from combustion gas to the air stream added to the combustion zone.


Air pressure
The total gas pressure (static plus velocity).
Air pump
A pump which is used to deliver air to the aquarium. The pump pushes air through silicon tubing and to air stones or other aquatic decor. They are also an essential for UGF's (undergravel filters). An air stone is placed in each clear tube. When the air bubbles travel upward, they generate steady current which brings water from the bottom, through the tubes and to the surface.
Air receiver
A receptacle which serves to store compressed air for heavy demands in excess of compressor capacity.
ALT
ACRONYM - Altitude

Altitude
The elevation of a compressor above sea level.
Alternating current (AC)
An electrical current that periodically reverses its direction. Standard in US and Canada is 60 cycles per second. Europe and other countries is 50 cycles per second.

 

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Amagat's law
States that the volume of a mixture of gases is equal to the sum of the partial volumes which the constituent gases would occupy if each existed alone at the total pressure of the mixture.
Ambient
Undisturbed environmental surroundings, particularly to air and temperature.
Ammonia
A colorless gaseous compound of nitrogen and hydrogen used in refrigeration and in making of fertilizers and explosives. Found in some ambient air conditions.
Amonton's law
States that the pressure of a gas, at constant volume, varies directly with the absolute temperature.
AMP
ACRONYM - A unit of electrical current or rate of flow of electrons through a conductor. One volt across one ohm of resistance causes a current flow of one ampere. One ampere is equal to 6.25 x 1018 electrons per second passing a set point in a circuit. Ampere
Ampere (AMP)
A unit of electrical current or rate of flow of electrons through a conductor. One volt across one ohm of resistance causes a current flow of one ampere. One ampere is equal to 6.25 x 1018 electrons per second passing a set point in a circuit.
Ancillary equipment
Components subordinate to the compressor.
Anhydrous
devoid of water.

Anion
A negatively charged ion.

ANLG
ACRONYM - Analog

ANR
ACRONYM - Atmosphere normale de reference. The term ANR is not usually applied to cfm, it is the new European replacement for FAD and usually follows the metric measurement of air flow, such as Cu Meters per Minute
Anti re-entrainment sock
The outer layer on a coalescing filter that prevents separated liquids from re-entering the air stream. Also known as anti re-entrainment barrier.
Anti-Pulsation Tank
Sometimes called a pulsation damper this is a small receiver fitted on the inlet or discharge of a reciprocating compressor. The device is designed to remove the resonance from the compressor thereby reducing noise.
AP
ACRONYM - Air pressure

A.P.I.
American Petroleum Institute
Artificial demand
Running a compressed air system at a higher than needed pressure.
ASHRAE
The American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., (ASHRAE) is an international membership organization operated for the exclusive purpose of advancing the arts and sciences of heating, refrigeration, air conditioning and ventilation, the allied arts and sciences, and related human factors for the benefit of the public.
A.S.M.E.
American Society of Mechanical Engineers

ASL
ACRONYM - Above sea level

A.S.T.M.
American Society For Testing and Materials. -- a society for developing standards for materials and test methods.
ATM
ACRONYM - Atmosphere

Atmosphere ( ATM )
The standard atmosphere is defined as the pressure exerted by a column of mercury 760 mm high with a density of 13,595 g/cm³ at the standard acceleration due to gravity of 9.8 m/s². The 760th part of this pressure unit is the torr. The technical atmosphere (at) denotes the pressure of a force of 1 kg acting on an area of 1 cm².
ATA
ACRONYM - Atmospheres absolute. It is the weight of the column of air existing above the earths surface at 45° Lat and sea level. Is equivalent to 14.696 psiA or 1.0333 kg/sq cm. Equals atmospheres gauge plus 1.

Atmospheres absolute (ATA)
It is the weight of the column of air existing above the earths surface at 45° Lat and sea level. Is equivalent to 14.696 psiA or 1.0333 kg/sq cm. Equals atmospheres gauge plus 1.
Atmospheric boundry level
A region near the earth in which the relative velocity increases from zero with elevation, due to the motion of the atmosphere relative to the earth's surface.

Atmospheric dew point
Is the temperature at which water vapor begins to condense at atmospheric pressure. Is the same as dew point, but is related to atmospheric air only.
Atmospheric inversion
A term which describes the rising of warm air above cold air when two air masses of different temperatures, humidity and pressure meet.

Atmospheric pressure
Weight of the earth's atmosphere over a unit area of the earth's surface, measured with a mercury barometer at sea level. which corresponds to the pressure required to lift a column of mercury 760 mm.
Atomize
The breaking-up of paint into fine particles or droplets by a paint gun using compressed air.
Attenuation
The use of a sound barrier separating the sound from the receiver.
Automatic sequencer
A device which operates compressors in sequence according to a programmed schedule.
Avogadro's law
States that equal volumes of all gases under the same conditions of pressure and temperature contain the same number of molecules.
Axial compressor
A compressor belonging to the group of dynamic compressors. Characterized by having its flow in the axial direction.

BA
ACRONYM - Breathing air
Back pressure
Resistance to air flow; usually stated in inches H2O or PSI.
Bag blinding
A condition where the particles (dust) becomes embedded in the fabric filter over time and are not removed by the bag cleaning process.
Bag filter
a fabric bag through which a gas stream is passed for the removal of particulate matter.
Bag house
a dust-collection chamber containing numerous permeable fabric filters through which the exhaust gases pass. Finer particulates entrained in the exhaust gas stream are collected in the filters for subsequent treatment/disposal.
Bar
A unit of pressure equal to 0.99 atmospheres or 14.233 psi.
Bara
The pressure of a system or device measured from absolute zero.
Barg
Bar gauge (similar to the acronym "psig")
Barometric pressure
Is the absolute atmospheric pressure existing at any given point in the atmosphere. It is the weight of a unit column of gas directly above the point of measurement. It varies with altitude, moisture and weather conditions.
Base plate
A metallic structure on which a compressor or other machine is mounted.
Bead ring
A ring used to attach certain bellow type flexible members of an air actuators to the mounting surface.
Bernoulli's principle
In physics, the concept that as the speed of a moving fluid (liquid or gas) increases, the pressure within that fluid decreases. Originally formulated in 1738 by the Swiss mathematician and physicist Daniel Bernoulli, it states that the total energy in a steadily flowing fluid system is a constant along the flow path. An increase in the fluid's speed must therefore be matched by a decrease in its pressure.

Bernoulli's principle applies in nozzles, where flow accelerates and pressure drops as the tube diameter is reduced. It is also the principle behind orifice or Venturi flow meters. These meters measure the pressure difference between a low-speed fluid in an approach pipe and the high-speed fluid at the smaller orifice diameter to determine flow velocities and thus to meter the flow rate. Bernoulli's principle is sometimes mistakenly used to explain the net force in a system that includes a moving fluid, such as lift on an airplane wing, thrust of a ship's propeller, or drifting of a spinning baseball. The principle, however, only applies to systems that do not produce a net force.
Beta ratio
Efficiency measurement of any filter expressed by the number of particles of a given size upstream of the filter, divided by the number of particles of that size downstream of the filter.
BHP
ACRONYM - Break horse power
Bicarbonate
An acid carbonate.

BLDN
ACRONYM - Blowdown.

Blowdown (BLDN)
The difference in pressure between the opening pressure and reclose pressure of a valve. May be expressed in percentage of set pressure or "psig".
Blower (BLWR)
A compressor that is designed to operate at lower pressures. Usually a blower is an air compressor that operates below 2 barg, although this figure depends upon the respective manufacturer.
Blow off control
The compressor continuously compresses, however, when the maximum pressure is reached, the delivered air is blown off to the atmosphere instead of being fed to the receiver.

BLWR
ACRONYM - Blower.
Body
The stationary seating surface, the inlet of a valve.
Bonnet
The portion of a safety/relief valve that surrounds the spring. The spring housing.
Boolean logic
The logic of binary systems, such as control systems in which all operations may be reduced to on-off, open-closed, or similar dichotomous basis.
Booster
A machine which aspirates gas which has already been compressed and delivers the same at higher pressure.
BP
ACRONYM - Back pressure.
Boyle's law
States that the volume of a gas, at constant temperature, varies inversely with the pressure.
Brake horse power (BHP)
The maximum rate at which an engine can do work as measured by the resistance of an applied brake. Expressed in horsepower.
Branch lines
Are lines that supply equipment from sub headers.
Breakdown maintenance
Maintenance performed after a machine has failed to return it to an operating state.
Breaker
A hand held pneumatic tool. Designed for light demolition work, digging, making holes etc.
Breaking pressure
Is that pressure of either the motive fluid or of the ejector gas discharge which causes an ejector to become unstable.
Breather
A filtering unit for vented enclosures installed to prevent dirt and foreign matter from entering the enclosure.
Breathing air
Specialty compressed air treatment meeting OSHA Grade D breathing air requirements.
Bridging
A condition of filter element loading in which contaminant spans the space between adjacent sections of a filter element, thus blocking a portion of the useful filtration.
Brownian diffusion
The slight deflection of very small particles in a gas stream that occurs when rapidly moving gas molecules strike them.

British thermal unit
BTU. The amount of heat required to raise the temperature of one pound of water one degree Fahrenheit under set conditions of temperature and pressure.
BSPP
ACRONYM - British standard pipe parallel.
BSPT
ACRONYM - British standard pipe tapered.
BTU
ACRONYM - British thermal unit. The amount of heat required to raise the temperature of one pound of water one degree Fahrenheit under set conditions of temperature and pressure.
Bubble
In spray painting applications, air trapped in a paint film caused by poor atomization during spraying.
Built-in-dirt
Material passed into the effluent stream composed of foreign materials incorporated into the filter medium.
Built up back pressure
The increase in pressure in the discharge header that develops as a result of flow after the pressure relief device opens
Bumper
An internal compression stop. Generally a molded rubber part attached inside an air actuator.
Buna N
A synthetic rubber frequently used for vessel and liquid filter element gasket.
Burst pressure
Maximum pressure a vessel, or air filter housing will withstand without bursting.
By pass
Condition that exists when the air, gas, or fluid normally passing through an element is being shunted around the element.
By pass valve
An automatic or manual valve that causes the flow to be by passed.



Can velocity
The velocity of the gas in the passages between the filter units in the filter house of a gas filter.

Cap
The pressure screw cover and/or lever housing on a valve. May be screwed, bolted. packed, or plain lever.
Capacity
Capacity of a compressor is the full rated volume of flow of gas compressed and delivered at certain set conditions.
Capacity filtration
The amount of air that a filter can handle. Expressed in CFM.
Capacity gauge
A gauge that measures air flow as a percentage of capacity, used in rotary screw compressors as an estimator during modulation controls.
Capillary tube
A restrictive tube used in a refrigeration system which restricts the flow of freon and allows pressure to build on one side and suction on the other. It is located between the condenser and the evaporator.
Cap tube
A restrictive tube used in a refrigeration system which restricts the flow of freon and allows pressure to build on one side and suction on the other. It is located between the condenser and the evaporator.
Carbonate
A salt or ester of carbonic acid.
Carbon dioxide
A heavy colorless gas that does not support combustion but is formed by the combustion and decomposition of organic substances. Found in some ambient air conditions.
Carbon monoxide
A colorless odorless very poisonous gas formed by the incomplete burning of carbon. Found in some ambient air conditions.
Carbon residue
The carbon left after evaporating an oil under controlled conditions.
Casing
The pressure containing stationary element that encloses the rotor and associated internal components of a compressor, including integral inlet and discharge connections.
Celsius
°C The international temperature scale where water freezes at 0 (degrees) and boils at 100 (degrees). Also known as the centigrade scale.
Center tube
The internal duct and filter medium support
Centrifugal compressor
A dynamic compressor. A machine in which air or gas is compressed by the mechanical action of rotating vanes or impellers imparting velocity and pressure to the air or gas. In a centrifugal compressor, flow is in a radial direction. Air enters the compressor through the machine mounted inlet control valve and flows to the first stage where the impeller imparts velocity energy to the air. The air then proceeds through a diffuser section which converts the velocity energy to pressure energy. A multistage centrifugal compressor is a machine having two or more of these stages.
CFM
ACRONYM - Cubic feet per minute. An airflow measurement of volume.
Charle's law
States that the volume of a gas, at constant pressure, varies directly with the absolute temperature.
Chatter
Abnormal, rapid reciprocating movement of the disc on the seat of a pressure relief valve.
Chip control
a filter intended to prevent only large particles from entering a component immediately downstream.
Chipping hammer
A hand held pneumatic tool. Designed to chip masonry, plaster, concrete etc.
Check valve
A valve that permits flow in one direction only.
Chlorine
A chemical element that is a heavy strong smelling greenish yellow imitating gas used as a bleach, oxidizing agent and disinfectant. Found in some ambient air conditions.
Chlorofluorocarbons (CFCs)
Compounds containing chlorine, fluorine or bromine, used as aerosol propellants, refrigerants, foaming agents and solvents and which, on decomposition by sunlight, produce oxides of chlorine responsible for the removal of ozone from the stratosphere.

Choke
This term is used for turbo compressors and represents the maximum flow condition. It is sometimes also referred to as stonewalling.
Cleanable
A filter element which, when loaded, can be restored by a suitable process, to an acceptable percentage of its original dirt capacity.
Cleanliness level
a measure of relative freedom from contaminants.
Clean room
A facility or enclosure in which air content and other conditions (such as temperature, humidity, and pressure) are controlled and maintained at a specific level by special facilities and operating processes and by trained personnel.
Clean pressure drop
The pressure loss across the filter element determined under steady state flow conditions using a clean test fluid across a clean filter element.
Clearance
The maximum cylinder volume on a working side of the piston, minus the piston displacement volume per stroke. It is usually expressed as a percentage of the displace volume.
Clearance pocket
An auxiliary volume that may be opened to the clearance space for increasing the clearance, usually temporarily, to reduce the volumetric efficiency of the compressor.
Clevis
A device for mounting cylinders.
Collapse
An inward structural failure of a filter element which can occur due to abnormally high pressure drop (differential pressure) or resistance to flow.
Collapse pressure
The minimum differential pressure that an element is designed to withstand without permanent deformation.
CNG
ACRONYM - Compressed natural gas, primarily methane.
Closed loop system
A system in which distilled water, antifreeze, and/or corrosion inhibitors are circulated through a collector and storage tank in a closed loop. Heat picked up from the collector by the circulating fluid is transferred to the storage tank through the closed loop or other heat exchangers.
Coalescing filter
A filter unit that combines three principles to filter out oil aerosols: 1) Direct interception - A sieving action, 2) Inertial impaction - Collision with filter media fibers, 3) Diffusion -Particles travel in a spiral motion, presenting an effective frontal area thus capturing particles within the filter medium.
Code
The A.S.M.E. Boiler and Pressure Vessel Code.
Coefficient of discharge
The ratio of the measured relieving capacity to the theoretical relieving capacity.
Cold differential test procedure
Actual gage pressure on the test stand that includes correction factors for temperature, pulsation, vibration, constant back pressure, etc.
Cold start
Starting a compressor from a state of total shutdown. Usually done with "local" control at the compressor. May be done with "remote" control, but only advised with "heavy" instrumentation and monitoring accessories.

Compensator
An expansion joint designed to take up thermal expansion.
Composition of air
A colorless, odorless, tasteless gas. A mixture of individual gases. The gaseous mixture surrounding the earth..
Compressed
To reduce the volume of, by or as if by pressure.
Compressed air
Air under pressure greater than that of the atmosphere.
Compressed air challenge
A public/private initiative to promote the efficiency of compressed air in the US.
Compressibility
A factor expressing the deviation of gas from the laws of hydraulics.
Compressibility factor Z
Is the ratio of the actual volume of the gas to the volume determined according to the perfect gas law.
Compression adiabatic
Compression in which no heat is transferred to or from the gas during the compression process.

 

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Compression efficiency
Is the ratio of the theoretical work requirement to the actual work required to be performed on the gas for compression and delivery.
Compression Isothermal
Is a compression in which the temperature of a gas remains constant.
Compression ratio
The ratio of the absolute discharge pressure to the absolute inlet pressure.
Compressor
A machine that compresses air, gases.
Computer control
May be "local" using a micro-processor or "remote" using a PC (Personal Computer) or "larger" computer. Only recommended where large "swings" in system (process) demand amplitude may occur. Very effective where "load shaping" is an important consideration. "Heavy" monitoring and instrumentation accessories required for it to be efficient and effective. Usually not necessary where system demand is predominantly constant.
Condensate
the liquid that separates from a vapor during condensation.
Condenser
A device that changes a vapor into a liquid. Accomplished by exposing a tube containing vapor to air or by passing the tube through a water jacket.
Conduction
The transfer of heat energy through a material (solid, liquid, or gas) by the motion of adjacent atoms and molecules without gross displacement of the particles.
Connector
The mating device that is inserted into the coupler of a quick coupler and locked to complete the connection. Also referred to as plug or nipple.
Constant speed control
The unit that runs continuously and matches air supply to demand, by loading and unloading the compressor.
Contaminant
Foreign matter carried in the air, gas or fluid to be filtered out. Includes air borne dirt, metallic particles produced by wear of moving parts of the air compressor, rust from metal pipelines.
Contaminant capacity
the weight of a specified artificial contaminant that must be added to the influent to produce a given differential pressure across a filter at specified conditions. Used as an indication of relative service life.
Contaminant failure
any loss of performance due to the presence of contamination. Two basic types of contamination failure are: Perceptible -- gradual loss of efficiency or performance, and Catastrophic -- dramatic, unexpected failure.
Control valve
A valve that controls the flow in air lines.
Convection
Is a means of transferring heat through mass flow. Also the transfer of heat within a fluid by movements within the fluid.
Convolution
On a bellow type air actuator, that part of the flexible member forming an annular protrusion larger than the O.D. of the end retainers or bead rings.
Coolant
Fluid cooling agent.
Cooling tower
A cooling water supply system. There are two different types - Open and closed loop systems.
CPM
ACRONYM - Cycles per minute - a unit of measure of the frequency of any vibration.
Cracking
To subject petroleum oil to heat for breaking down into lighter products.
Critical pressure
Is the saturation pressure at the critical temperature. It is the highest vapor pressure that the liquid can exert.
Critical speed
Rotative speeds at which rotating machinery-axial or screw lobe-pass through unbalanced operation.
Critical temperature
The highest temperature at which well-defined liquid and vapor states exist.
Crosshead assembly
The assembly connecting the crankcase and connecting rod to the cylinder head and piston rod for translating circular to linear motion.
Crosshead compressor
A compressor belonging to the group of displacement reciprocating compressors.
Crosshead loading
The tensile or compressive loading on the crosshead assembly with compressive piston rod loading on the outward stroke and tensile piston rod loading on the inward stroke.
CSA
ACRONYM - Canadian Standards Association
CTD
ACRONYM - Approach temperature. Usually the difference between cooling water temperature in to compressed air temperature out of an inter-cooler or after-cooler. Sometimes used to define oil cooler efficiency (cooling water temperature in to oil temperature out)
Cubic feet per minute (CFM)
CFM. An airflow measurement of volume.
cu m/sec
A volume. Cubic meters per second.
Cut in cut out pressure
The settings on a pressure switch used to either load or unload the air compressor on a constant speed application, or start or stop the compressor on a start/stop application. The cut out pressure is also known as the maximum pressure, or the point at which there is no air being delivered. The cut in pressure is referred to as the minimum pressure, or the pressure that the system is allowed to fall to before air volume is required.
Cycle
A single complete operation consisting of progressive phases starting and ending at the neutral position.
Cycle time
Amount of time for a compressor to complete one cycle.
Cylinder
The piston chamber in a compressor or actuator.
Cyclone
a type of separator for removal of larger particles from an exhaust gas stream. Gas laden with particulates enters the cyclone and is directed to flow in a spiral causing the entrained particulates to fall out and collect at the bottom. The gas exits near the top of the cyclone.

Cyclone separator
A means of purifying an air stream by using both gravitational and centrifugal forces.

Dalton's law
States that the total pressure of a mixture of gases is equal to the sum of the partial pressures of the constituent gases. The partial pressure is the pressure each gas would exert if it alone occupied the volume of the mixture.
DC
Direct current. A continuous, one directional flow of electricity
Dead end pressure
Is the suction pressure attained by an ejector or positive displacement vacuum pump at zero capacity with the suction absolutely blanked off.
Degrees Celsius (°C)
An absolute temperature scale. ((°F - 32)x 5/9).
Degrees Fahrenheit (°F)
An absolute temperature scale. ((°C x 9/5) + 32).
Degrees Kelvin (°K)
An absolute temperature scale. The kelvin unit of thermodynamic temperature, is the fraction 1/273,16 of the thermodynamic temperature of the triple point of water. The triple point of water is the equilibrium temperature (0,01 °C or 273,16 K) between pure ice, air free water and water vapour.
Degree Rankine (°R)
An absolute temperature scale. (°F + 459,67).
Degree Réaumur (°Ré)
An absolute temperature scale. ((°F - 32) x 4/9).
Degree of intercooling
Difference in air or gas temperature between the outlet of the intercooler and the inlet of the compressor.
Degree of saturation
Is the ratio of weight of vapor existing in a given space to the weight that would be present if the space were saturated at the space temperature.
Deliquescent
Melting and becoming a liquid by absorbing moisture.
Deliquescence
A solid absorption agent used in deliquescent type dryers.
Delta P
Describes the pressure drop through a component and is the difference in pressure between two points.
Delta T
A term indicating a temperature relationship between two temperatures or temperature variation between two points.
Demand
Flow of air under specific conditions required at a particular point.
Demand side management (DSM)
The planning and implementation of strategies designed to encourage consumers to improve energy efficiency, reduce energy costs, change the time of usage, or promote the use of different energy source.
Demulsibility
The ability of a fluid that is insoluble in water to separate from water with which it may be mixed in the form of an emulsion.
Density
Is the weight of a given volume of gas, usually expressed in lb / cu ft at SPT condition.
Depth filter
a filter medium that retains contaminants primarily within tortuous passages.
Desiccant
An adsorption type material used in compressed air dryers. Industry standards are activated alumina, silica gel and molecular sieves.
Design pressure
The maximum continuous operating pressure as designed by the manufacturer.
Desorption
Opposite of absorption or adsorption. In filtration, it relates to the downstream release of particles previously retained by the filter.
Dew point
Of a gas is the temperature at which the vapor in a space (at a given pressure) will start to condense (form dew). Dew point of a gas mixture is the temperature at which the highest boiling point constituent will start to condense.
Dew point cup
An apparatus consisting of a small, polished, stainless steel cup placed in a container into which is passed the sample gas. The temperature of the polished surface is lowered by immersing dry ice (solid carbon dioxide) in an acetone solution contained in the cup. The temperature at which fog appears on the cup is the dew point of the sample.
Diaphragm
A stationary element between stages of a multistage centrifugal compressor. It may include guide vanes for directing the flowing medium to the impeller of the succeeding stage. in conjunction with an adjacent diaphragm, it forms the diffuser surrounding the impeller.
Diaphragm compressor
Is a positive displacement reciprocating compressor using a flexible membrane or diaphragm in place of a piston.
Diaphragm cooling
A method of removing heat from the flowing medium by circulation of a coolant in passages built into the diaphragm.
Differential pressure
The difference in pressure between any two points of a system or component.
Differential pressure indicator
an indicator which signals the difference in pressure between any two points of a system or a component.
Diffuser
A stationary passage surrounding an impeller, in which velocity pressure imparted to the flow medium by the impeller is converted into static pressure.
Direct current
DC. A continuous, one directional flow of electricity.
Directional control valve
A valve to control the flow of air in a certain direction.
Dirt holding capacity
The quantity of contaminant a filter element can trap and hold before the maximum allowable back pressure or delta P level is reached.
Disc
The movable seating surface in a valve.
Discharge piping
Is the piping between the compressor and the aftercooler, the aftercooler separator and the air receiver.
Discharge pressure
Is the total gas pressure (static plus velocity) at the discharge port of the compressor. Velocity pressure is considered only with dynamic compressors.
Discharge temperature
Is the temperature existing at the discharge port of the compressor.
Displacement compressor
A machine where a static pressure rise is obtained by allowing successive volumes of gas to be aspirated into and exhausted out of a closed space by means of the displacement of a moving member.
Displacement of a compressor
The volume displaced by the compressing element of the first stage per unit of time.
Disposable filter
a filter element intended to be discarded and replaced after one service cycle.
DOE
The U.S. Department of Energy.
DOP
Dioctylphalate aerosol (Efficiency Test Material).
Double acting compressor
A positive displacement type compressor.
Downstream
The portion of the flow stream which has already passed through the system or the portion of the system located after a filter or separator/filter.
Drag
Occurs when a valve does not close completely after popping and remains partly open until the pressure is further reduced.
Drain valve
A device designed to remove surplus liquid from the compressed air system. Manual units range from petcock to a ball, gate or globe valve. Mechanical types consist of ball float. Electrical drains include solenoid type that is energized by a timer signal, or electric motor driven units. Also pneumatically activated drains.
Dripleg
Is a pipe extending downward from the bottom of the airline to collect any condensation flow in the pipe.
Drive
A coupling between the compressor and the engine or motor. The three types of drives most common are; flange mounted motor, V belt drive or direct coupling.
Dropleg
Is a pipe coming from the top of the airline to feed air to an outlet for tools or air operated devices, so that condensation does not easily flow into the dropleg.
Dry adiabatic lapse rate
Rate at which unsaturated air cools as it travels vertically, provided that all temperature change is adiabatic (without heat exchange), and no condensation occurs.
Dry bulb temperature
Is the ambient gas temperature as indicated by a standard thermometer.
Dry gas
Is any gas or gas mixture that contains no water vapor and/or in which all of the constituents are substantially above their respective saturated vapor pressures at the existing temperature.
Dry unit (oil free)
Is one in which there is no liquid injection and/or liquid circulation for evaporative cooling or sealing.
Dynamic losses
Friction against duct walls, internal friction in the air mass and direction variations will cause a speed reduction and are therefore called dynamic losses.
Dynamic type compressors
Machines in which air or gas is compressed by the mechanical action of rotating vanes or impellers imparting velocity and pressure to the flowing medium. (Raise the pressure of the air by converting the energy from the velocity of the air to pressure.)
Dynamic viscosity ( Dynamic )
Is the force in newton required to move a fluid layer of one square meter area and a thickness of one meter with a velocity of one meter per second.
Dual control
Load/unload control system that tries to maximize compressor efficiency by matching air delivery and air demand. Compressor is operated at full load or idle.
Duct
A pipe, tube or channel that conveys a substance (such as air throughout a building).
Durometer
This term refers to the hardness or softness of gaskets.
Dust cake
A layer of dust built up on an air filter.
Dust holding capacity
The amount of atmospheric dust which a filter will capture.
Duty cycle
Percentage of time a compressor unit can operate at full load over a thirty minute period.

Effective area
The area (in sq inches) of the filter element that is exposed to the flow of air or fluid for effective filtering.
Efficiency
Ability of a filter to remove particle matter from an air stream. Measured by comparing concentrate of material upstream and downstream of the filter. Typical particulate sizes range from .3 micron to 50 micron.
Efficiency compression
Is the ratio of the theoretical work requirement to the actual work required to be performed on the gas for compression and delivery.
Efficiency isothermal
Is the ratio of the theoretical work calculated on an isothermal basis to the actual work transferred to the gas during compression.
Efficiency mechanical
Is the ratio of the thermodynamic work requirement in the cylinder to actual brake horsepower requirement.
Efficiency polytropic
Is the ratio of the polytropic compression energy transferred to the gas to the actual energy transferred to the gas.
Efficiency volumetric
Is the ratio of actual capacity to piston displacement, stated as a percentage.
Ejector compressor
A compressor belonging to the group of dynamic compressors.
Element
The medium or material that does the actual filtering or separating. May be paper, wire mesh, special cellulose, inorganic plastic, or a combination.
Emulsibility
The ability of a non-water-soluble fluid to form an emulsion with water.
Emulsifier
Additive that promotes the formation of a stable mixture, or emulsion, of oil and water. Common emulsifiers are: metallic soaps, certain animal and vegetable oils, and various polar compounds.
Emulsion
Intimate mixture of oil and water, generally of a milky or cloudy appearance. Emulsions may be of two types: oil-in water (where water is the continuous phase) and water-in-oil (where water is the discontinuous phase).
End cap
A ported or closed cover for the end of a filter element.
Energy audit
A survey that shows how much energy you use in your compressed air generation. It will help find ways to use energy more efficiently.
Energy conservation
Practices and measures that increase energy efficiency.
Energy kinetic
Is the energy a substance possesses by virtue of its motion or velocity. Used primarily in calculations for dynamic and ejector type compressors.
Energy storage
The ability to convert energy into other forms, such as heat or chemical reaction, so that it can be retrieved for later use. Also the development, design, construction and operation of devices for storing energy until needed. Technology includes devices such as compressed gas.
Enthalpy
Is the sum of the internal and external energies.
Entrainment ratios
Are used with ejectors to convert weight of gas and/or water vapor handled to or from equivalent air.
Entropy
Is a measure of the unavailability of energy in a substance.
Environmental contaminant
all material and energy present in and around an operating system, such as dust, air moisture, chemicals, and thermal energy.
Evaporation
The escape of water molecules from a liquid to the gas phase at the surface of a body of water.
Evaporator
The chamber located on suction side of cap tube, in which freon is evaporated to cause cooling in a refrigeration system.
Exothermic
A term used to describe a chemical process in which heat is released. For example, combustion is an exothermic process because heat is released.

 

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Expanders
Turbines or engines in which gas expands, does work, and undergoes a drop in temperature.
FAD
Free air delivery. Air at the atmospheric conditions of the site and unaffected by the compressor. Flow is measured at the discharge valve of the compressor, after the aftercooler, the water separator and built in check valve. Capacity and power consumption are corrected to ISO 1217 standard reference conditions: Ambient temperature = °20C, Ambient pressure = 1 bar(a), Relative humidity = 0%, Cooling water/air = 20°C, Effective working pressure at discharge valve = 7 bar(a).
Fatigued
A structural failure of the filter medium due to flexing caused by cyclic differential pressure.
Ferrography
An analytical method of assessing machine health by quantifying and examining ferrous wear particles suspended in the lubricant or hydraulic fluid.
Fick's law of diffusion
A law of chemistry and physics: the rate of diffusion of one substance in another is proportional to the negative gradient of the concentration of the first substance.
Filter
A device that removes solid contaminants, such as dirt or metal particles, from a liquid or gas (air is a gas), or that separates one liquid from another, or a liquid from a gas. The term filter describes the complete unit ... housing, filter element, internal by pass.
Filter breather
A filtering unit for vented enclosures installed to prevent dirt and foreign matter from entering the enclosure. Also prevents oil loss by retaining oil droplets and draining the oil back to the sump.
Filter coalescing
A filter unit that combines three principles to filter out oil aerosols: 1) Direct interception - A sieving action, 2) Inertial impaction - Collision with filter media fibers, 3) Diffusion -Particles travel in a spiral motion, presenting an effective frontal area thus capturing particles within the filter medium.
Filter efficiency
The ability of a filter to remove specified test contaminants under specified test conditions from a specific test fluid, air, gas or liquid. Expressed as a percentage of the quantity of test contaminant introduced into the inlet of the filter test system
Filter element
The porous device which perform the actual process of filtration.
Filter head
An end closure for the filter case or bowl that contains one or more ports.
Filter housing
Something that covers or protects the filter assembly.


Filter inline
Inlet and outlet connections are located at the same level on opposite sides of the filter or other device installed on the pipeline.
Filter life test
A type of filter capacity test in which a clogging contaminant is added to the influent of a filter, under specified test conditions, to produce a given rise in pressure drop across the filter or until a specified reduction of flow is reached. Filter life may be expressed as test time required to reach terminal conditions at a specified contaminant addition rate.
Filter medium
The porous material contained inside the filter to (a) separate the contaminants from the incoming air, gas, or liquid. (b) separate the liquid from the gas. Filter medium is usually made of paper, wire mesh, special cellulose, or a combination.
Filter oil bath
A labyrinth type filter having the active surfaces continuously splashed with oil. Most pollutants are absorbed by the oil which when circulated releases its pollutants, which sink by gravity to the bottom of the oil pan.
Filter separator
Filtering unit that separates solids and liquid droplets from gas (air). Widely used in removing oil from a gas or air.
Filtration
The physical or mechanical process of separating insoluble particulate matter from a fluid, such as air or liquid, by passing the fluid through a filter medium that will not allow the particulate to pass through it.
First law of thermodynamics
The amount of work done on or by a system is equal to the amount of energy transferred to or from the system.
Fixed compression ratio
is the design (built-in) compression ratio for a rotary unit having this feature
Flange
A bolted rim used for attachment to another object.
Flash point
Is the lowest temperature to which oil must be heated under standardized test conditions to drive off sufficient inflammable vapour to flash when brought into contact with a flame. Flash points of petroleum based lubricants increase with increasing pressure.
Flexible mounting
Vibration isolation mount. Provides reductions in vibration transmission.
Flow
The volume of a substance passing a point per unit time (e.g., meters per second, gallons per hour, etc.).
Flow control valve
A valve that controls the flow of air that passes through the valve. Used often for retardation or timing circuits, but especially for regulating the piston speed in cylinders.
Flow diagram
A schematic flow sheet showing all controls involved with the system.
Flow meter
An instrument for measuring the amount of air flow of a compressor. Measured in CFM.
Flow rate
The rate (in liters or gallons per minute, cubic meters or cubic feet per second, or other quantity per time unit) Air related flows are usually expressed in CFM, SCFM, ACFM, ICFM
Flushing
A circulation process designed to remove contamination.
Foot
A device for mounting cylinders.
Forced draft fan
A fan that generates (by pushing) a flow of ambient air over the exterior of the finned pipes to dissipate the sensible heat.
Fouling
Accumulation of foreign matter, such as mud or debris, in a cooler, pipe, or valve. In a cooler, H 2 O P and T will be seen to increase, as well as CTD.
Free air (FAD)
Free air delivery. Air at the atmospheric conditions of the site and unaffected by the compressor. Flow is measured at the discharge valve of the compressor, after the aftercooler, the water separator and built in check valve. Capacity and power consumption are corrected to ISO 1217 standard reference conditions: Ambient temperature = °20C, Ambient pressure = 1 bar(a), Relative humidity = 0%, Cooling water/air = 20°C, Effective working pressure at discharge valve = 7 bar(a).
Friction
Surface resistance to relative motion, which slows down movement and causes heat.
FRL
Filter, Regulator and lubricator sometimes combined in one unit
Frost point
Is the unique temperature to which the air (or any gas) must be cooled in order that it shall be saturated with respect to ice.
Full load
Achieved when the air compressor is running at full RPM with a fully opened inlet and discharge, delivering the maximum volume at the rated pressure.

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
Head adiabatic
The energy in foot pounds required to compress adiabatically and to deliver one pound of a given gas from one pressure level to another.
Header
The main distribution pipe.
Head polytropic
The energy in foot pounds required to compress polytropically and to transfer one pound of a given gas from one pressure level to another.
Head pressure
A term used to describe the hot gas pressure on the outlet side of the refrigeration compression.
Heat exchanger
Is used to cool compressed air or gas. Designed to reduce the temperature and liquefy condensate vapors.
Heatless dryer
Heatless reactivated dryer. By means of expanding cold dry air to near atmospheric pressure inside the regeneration tower, the dryer air picks up moisture from the saturated desiccant bed and is then purged to atmosphere.
Heat reactivated dryers
Are categorized as internal or external heat reactivated. Internal type - Process air enters the dryer through the inlet piping, is then dried as it passes through the desiccant bed, and discharges through the outlet piping as dry air. Regeneration of the desiccant is accomplished at atmospheric pressure, using steam or electric heaters, embedded in the desiccant bed. External type - Process air enters the dryer through the inlet piping, is then dried as it passes through the desiccant bed, and discharges through the outlet piping as dry air. Reactivation is accomplished using a reactivation blower or a cooler.
Heat recovery
Recovering and utilizing the heat content of the compressed air.
High efficiency filtration
The unofficial filtration industry description for filters designed to trap small size contaminants.
High volume low pressure
In spray painting applications, Spray equipment which delivers material at a low pressure of no more than 10 PSI (at the air cap), however, with greater volume of air.
Horsepower (HP)
Is a unit of work equal to 33,000 foot pounds per minute, 550 foot pounds per second, or 746 Watts.
Horsepower brake (BHP)
The horsepower input to the compressor shaft, or more generally to any driven machine shaft.
Horsepower gas
The actual work required to compress and deliver a given gas quantity, including all thermodynamic, leakage and fluid friction losses. It does not include mechanical losses.
Horsepower ideal
The horsepower required to isothermally compress the air or gas delivered by the compressor at specified conditions.
Horsepower indicated
The horsepower calculated from compressor-indicator diagrams. Applied only to displacement type compressors.
Horsepower peak
The maximum power required by a given compressor when operating at a (1) constant discharge pressure with variable intake pressure, or (2) constant intake pressure with variable discharge pressure.
Horsepower theoretical
The horsepower required to compress adiabatically the air or gas delivered by the compressor through the specified range of pressures.
Hot gas
A term applied to the gas found on the high pressure side of the refrigeration system.
Hot gas bypass valve
A valve which connects the high pressure side of a compressed air system to the suction side and is adjusted so as to maintain a specific pressure on the suction side by controlled bleeding of hot gas to the suction side.
Hot start
The compressor is started automatically, depending on demand. Control panel is energized with no "pre-start" cycle required, as pre-lubrication pump and buffer (seal) air are always "on". A state of pre-start exists. Steam turbine compressors are "slow-rolling" to maintain "pre-start" turbine temperatures at an adequate, recommended level. "Heavy" instrumentation and monitoring accessories are recommended.
Housing
A ported enclosure which directs the flow of a gas through the filter element.
Humidity
The moisture content of air.
Humidity specific
The weight of water vapor in the air vapor mixture per pound of dry air.
Humidity relative
The relative humidity of a gas (or air) vapor mixture is the ratio of the partial pressure of the vapor to the vapor saturation pressure at the dry bulb temperature of the mixture.
HVLP
In spray painting applications, spray equipment which delivers material at a low pressure of no more than 10 PSI (at the air cap), however, with greater volume of air.
Hydrocarbons
Chemicals containing carbon and hydrogen.
Hydrogen chlorofluorocarbons (HCFC)
Chemical species slated to replace CFCs in the near future.
Hygroscopic cells
Are any material with an affinity for moisture. These analyzers use sensing elements that contain moisture adsorbing material. A change in the moisture content of the element is detected by an electric network and is used as a measurement of dew point

IBV
Inlet butterfly valve. These are fitted on the inlet of most types of compressor and the valve opens and closes to throttle the air flow. However, the term IBV is usually associated with turbo compressors.
ICFM
CFM flowing through the compressor inlet filter or inlet valve under rated conditions
I.D.
A measurement. Inside diameter.
Ideal gas
Is a gas that follows the perfect gas laws without deviation. There is no such thing, however it is the basis from which calculations are made and corrections applied.
Ideal multi stage compression
The condition when a perfect gas is isentropically compressed, and the gas inlet temperature and also the amount of work spent is the same for each stage.
IGV
Inlet guide-vane valve. Valve assembly at the air inlet of a "blower" (single stage, low pressure, centrifugal air compressor). Usually advised to be mounted in very close proximity to the "blower" impeller. Provides "pre-swirl" of air flow in same rotational direction as "blower" impeller. Proven to improve efficiency (reduced bhp) during throttled-down modulation of "blowers". Effectiveness, when used with multi-stage centrifugal air compressors, degrades rapidly.
Immiscible
Incapable of being mixed without separation phases. Water and petroleum oil are immiscible under most conditions, although they can be made miscible with the addition of an emulsifier.
Impeller
The part of the rotating element of a dynamic compressor that imparts energy to the flowing medium by means of centrifugal force. It consists of a number of blades mounted so as to rotate with the shaft.
Inches of water
A measurement of vacuum or pressure that is used to measure the airflow restriction.
Indicated power
Power as calculated from compressor-indicator diagrams.
Indicator card
A pressure-volume diagram for a compressor or engine cylinder produced by direct measurement made by the use of a device called an indicator.
Indicator pressure
An indicator that signals pressure conditions.
Induced draft
An air flow caused by a fan that draws air through the heat exchanger core in a uniform pattern to dissipate the sensible heat.
Inducer
A curved inlet section on an impeller.
Inert gas
Is one that does not enter into known chemical combination, either with itself or another element. There are four known gases of this type: helium; neon; argon and krypton. or a gas that does not supply any of the needs of combustion.
Inertia base
A concrete foundation with lateral supports which rests upon a number of steel springs. Designed to deal with disturbing frequencies in vibration isolation
Inertia forces
When reciprocating compressors run, the moving parts such as pistons, rods, crossheads, connecting rods are repeatedly accelerated and retarded. These velocity changes set up pulsating inertia forces. The forces are of the first and second order. The first order forces have the same frequency as the compressor shaft speed and the second order forces have a frequency twice the shaft speed.
Influent
The fluid entering a component.
Ingested contaminants
Environmental contaminant that ingresses due to the action of the system or machine.
Inlet pressure
Is the total pressure (static plus velocity) at the inlet flange of the compressor.
Inlet temperature
Is the temperature at the inlet flange of the compressor.
Inlet throttle
A compressor control mechanism designed to control performance output of the compressor to the demands of the plant process.
Inline filter
A filter assembly in which the inlet, outlet and filter element axes are in a straight line.

 

[Klavyeah]

Insolubles
Insoluble material suspended in the lubricating oil. This material may come from contamination or oil degradation.
Instrument air
A quality of compressed air for use with pneumatic instruments and controls. (usually dry and free from contaminants)
Intake filter
A device for separating solids or suspended particles in the air before they enter the air intake of the compressor.
Intake filter silencer
A device for separating solids or suspended particles in the air before they enter the air intake of the compressor and reduce intake noise as on reciprocating compressors through a silencing chamber in the filter housing.
Intank check valve
A valve designed to prevent air volume and pressure from escaping the compressor tank back into compressor heads while compressor is not operating.
Intercooler
Heat exchangers for removing the heat of compression between stages of a compressor.
Intercooling
The removal of heat from the air or gas between stages.
Internal energy
Energy which a substance possesses because of the motion and configuration of its atoms, molecules, and subatomic particles.
International Organization for Standardization
ISO.
Irreversible process
is one in which a portion of the original system energy is dissipated and cannot be returned to the system through its own operation. The system and/or surroundings cannot be returned to their original state.
Isentrop
Is a process taking place without any heat exchange with the surroundings.
Isentropic compression
An adiabatic compression with no increase in entropy; a reversible-adiabatic compression.
Isentropic efficiency
The ratio of the real gas isentropic power consumption to shaft input.
Isentropic power consumption
The power which is theoretically required to compress a gas under constant entropy from a given inlet pressure to a given discharge pressure. (calculated assuming ideal conditions).
ISO
International Organization for Standardization.
Isobar
Is a process taking place under constant pressure. To change the volume from state 1 to state 2, heat must be removed. The temperature change is proportional to the change in specific volume.
Isochor
Is a process taking place under constant volume. To raise the pressure from state 1 to state 2, heat must be added. The pressure change is proportional to the change in temperature.
Isotherm
Is a process taking place under constant temperature. To compress the gas from state 1 to state 2, heat must be removed to keep the temperature constant. The pressure change is reciprocal to the change in specific volume.
Isothermal compression
Is a compression in which the temperature of a gas remains constant.
Isothermal efficiency
The ratio of the isothermal power consumption to shaft input.
Isothermal power consumption
The power which is theoretically required to compress a gas under constant temperature, in a compressor free from losses, from a given inlet pressure to a given discharge pressure.

Jackleg
A pneumatic hand held percussive drill designed as a boring tool.
Jack hammer
A hand held rock drill worked by compressed air.
Jet
A stream of vapor, gas or liquid coming out fast from a narrow orifice.
Joule
A measurement. The international unit of energy. One joule is equal to one WATT - second or 0.737 foot pounds.
Joule effect
The conversion of mechanical, electrical or magnetic energy into heat.
Joule Thompson effect
When a perfect gas flows through a throttling with constant inlet and outlet pressures, the temperature of the gas is the same before and after it flows through the throttling. There is a temperature drop, however, during the passage of gas through the throttling device itself. At this point internal energy is transformed into kinetic energy with an accompanying temperature drop. However, for real gases there is a sustained change in temperature, even though the energy content of the gas remains constant. This is called the Joule Thompson effect.
Jounce
The compression of an air actuator (air spring) below its design height.
Journal
That part of a shaft or axle that rotates or angularly oscillates in or against a bearing or about which a bearing rotates or angularly oscillates.
Journal bearing
A sliding type of bearing having either rotating or oscillatory motion and in conjunction with which a journal operates. In a full or sleeve type bearing, the bearing surface is 360 degrees in extent. In a partial bearing, the bearing surface is less than 360 degrees in extent.
JTPF
Japanese tapered pipe thread (Female).
JTPM
Japanese tapered pipe thread (Male).

Kelvin (K)
The kelvin unit of thermodynamic temperature, is the fraction 1/273,16 of the thermodynamic temperature of the triple point of water. The triple point of water is the equilibrium temperature (o,01 °C or 273,16 K) between pure ice, air free water and water vapor.
KG/CM²A
Kilograms per square centimeter absolute.
Kickout type clutch
A type of clutch which has a spring loaded jaw or detented rolling element to control torque in an assembly tool.
Kilo
A thousand.
Kilobar (kb)
A unit of 1,000 bars of pressure.
Kilowatt (kW)
A unit of power equal to 1,000 watts.
Kilowatt hour (kWh)
A unit of work, being the work done in one hour at the rate of 1,000 watts.
Kinematic viscosity
Is the dynamic viscosity divided by the density
Kinetic energy
Is the energy a substance possesses by virtue of its motion or velocity. Used primarily in calculations for dynamic and ejector type compressors
Knock out
A term used to describe the condensate flow rate. It can be expressed as gallons per minute (GPM) or pounds mass per minute (lbm/min)
kPa
Kilopascal; a metric measure of pressure based on force per unit area. (1 kPa = 4.01 inches of water).
K value
Erosion rate per unit of erosion index in a cultivated continuous fallow soil.
kW
Kilowatt - A unit of power equal to 1,000 watts.
kWh
Kilowatt hour - A unit of work, being the work done in one hour at the rate of 1,000 watts.
Glossary Index

L/sec
Volume flow rate measured in liters per second
Labyrinth compressor
A special type of oil free, positive displacement reciprocating compressor, working without piston rings. The seal between piston and cylinder wall is produced by a series of labyrinths.
Lacquer
A deposit resulting from the oxidation and polymerization of fuels and lubricants when exposed to high temperatures. Similar to, but harder, than varnish.
Langelier's index
Is a technique for predicting whether water will tend to dissolve or precipitate calcium carbonate. If the water precipitates calcium carbonate, scale forming may result. If the water dissolves calcium carbonate, it has a corrosive tendency.
lb
Pounds.
lb/hr
A volume. Pounds per hour.
Leak air
A crack or hole that accidentally admits a gas or lets it escape.
Leak detector ultrasonic
An instrument designed to detect the ultrasonic emissions and convert them to audible signal.
Lift
The distance between the seat and disc seating surfaces when a valve is open.
Linear actuator
Air cylinder
Liner
Filter parts that provide protection and support for the filter media.
Liquid piston
A liquid piston compressor is a rotary compressor in which a vaned rotor revolves in an elliptical casing, with the rotor spaces sealed by a ring of liquid rotating with it inside the casing.
Liquid ring rotary compressor
A liquid piston compressor is a rotary compressor in which a vaned rotor revolves in an elliptical casing, with the rotor spaces sealed by a ring of liquid rotating with it inside the casing.
Load
Electrical measurement. The output of one or several electric machines. Load also denotes the power carried by a particular circuit.
Loaded
A filter element so full of contaminants that no longer can pass rated flow without excessive pressure differential.
Load factor
Ratio of the average compressor load during a given period of time to the maximum rated load of the compressor.
Load time
Time period from when a compressor loads until it unloads.
Lobe
A type of journal bearing in centrifugal air compressors.
Low pressure coat
In spray painting, the process of applying the final coat of paint at a lower air pressure. Used to uniform a finish or blending.
Lubrication
A material (such as oil) used between moving parts of machinery to make the surfaces slippery and reduce friction.
Lubricator
An instrument designed to add lubrication into the compressed air line.

M3/min M3/hr
Volume flow rate measured in cubic meters per minute (or per hour)
Mach number
is the ratio of the actual velocity at a given point to the velocity of sound in the same gas at the conditions existing at this point. These are known as local conditions.
Man way
An inspection cover or port in an air receiver tank.
MAWP
Maximum allowable working pressure. This data is found on the pressure vessel nameplate and is the maximum pressure at which the lowest set safety valve must be set (stamped).
Maximum operating pressure
The highest operating pressure the system or component is designed to withstand.
Mayonnaise
The oily condensate discharged by lubricated air compressors. The name is derived from the appearance of the condensate. Under normal conditions oily condensate should just be cloudy, like a small amount of milk in a bucket of water. When a lubricated compressor goes wrong, then the condensate becomes thick and sticky. In fact almost identical in appearance to the name it has been given.
Mechanical efficiency
The ratio of the indicated power to shaft input.
Media
A mat of fibers that provide a barrier to particles entrained in the flow of air or gas.
Media migration
Carry over of particles or contaminant from the filter or other filter materials into the clean side of the air flow.
Medium
Is singular for media and is the material...paper, wire, cellulose or a combination... from which the filter element is made and which does the actual filtration or separation.
Membrane dryer
Reduce dew point by passing compressed air through a bundle of hollow membrane fibers; water vapor and a portion of the compressed air then permeate the membrane walls and vent to atmosphere
Mesh size
Mesh is the number of openings in a square inch of screen or sieve. It is equal to the square of the number of strands of metal or plastic screening per lineal inch. Standard US mesh screen # 16 equates to a 1.19 millimeter particle diameter, mesh size #40 is 0.42 millimeters.
Micron
Micrometer or one millionth of a meter; micron is sometimes represented in filtration by the Greek letter µ (mu). A micron is 0.000039". Contaminant particles are measured by micron size and count.
Micron rating
A measurement applied to filters or filter media to indicate the particle size at which suspended solids above that size will be removed.
Millibar
A unit of atmospheric pressure equal to 1,000 dynes per sq. cm. or about 1/32 in. of mercury.
Mineral oil
The most commonly used lubricating oil for compressors.
MMCFD
Millions of cubic feet per 24 hour.
Modulating control
Compressor controls will run the compressor at varying loads to accommodate demand variations. Running a compressor at less than full load results in a drop in compressor efficiency and thus an increase in operating costs.

Modulating unload
The air compressor continues to run and air supply is matched to the demand by partial unloading. This can be accomplished by a regulator controlled floating inlet or by step unloading.
Moisture separator
A unit designed to separate condensate from the compressed air stream.
Moisture trap
A device designed to enable accumulated liquids to be held for draining in a compressed air system.
Molecular sieves
A solid adsorbent used for drying compressed air.

Molecular theory
All matter consists of molecules which are in constant motion, but which are held together by molecular forces. In a solid the molecules are closely packed and arranged in such a pattern that the influence of the molecular forces is very strong. This gives the solid its consistency and form. Molecular motion consists largely of oscillations around points of equilibrium. In a liquid the molecules are about as close as in a solid, but they are not arranged in a lattice and the cohesive forces are weaker. The molecules are more mobile in relation to each other, whereby the characteristic liquid phase develops; the liquid accommodated itself to the walls of the containing vessel, and its free surface aligns itself horizontally in response to the force of gravity. In a gas, however, the molecules are farther apart, and they move freely about each other since the molecular forces are not as strong. A gas therefore expands through space and mixes with other gasses present. The total volume of the molecules in a gas is very small in relation to the volume of the gas. A gas can therefore be compressed into a small part of its original volume.
Mottling
In spray painting applications, blotches of metallic or mica particles in a paint film caused by insufficient compressed air
MPCV
Combination minimum pressure valve and check valve.
MSDS
ACRONYM - MATERIAL SAFETY DATA SHEETS
Multistage axial compressor
A machine having two or more impellers operating in series on a single shaft and in single casing.
Multistage centrifugal compressor
A machine having two or more impellers operating in series on a single shaft and in single casing.
Multistage compressor
A machine employing two or more stages.

 

[Klavyeah]

N cu m/min N cu m/hr
Volume flow rate measured in normal cubic metres per minute (or hour), i.e. related back to normal inlet conditions
Natural frequency
A projecting aperture at the end of a tube, pipe etc. serving as an outlet for compressed air. Reduces the demand on the compressor by generating the highest thrust and volume for the lowest possible air consumption.
N.B.
ACRONYM - National Board of Boiler and Pressure Vessel Inspectors.
NEC
ACRONYM - National Electrical Code
Needle gauge
A measuring tool used to check air pressure at the tool by inserting a hypodermic needle into the rubber hose.
Needle scaler
A hand held pneumatic chipping tool which the blows are transmitted through a group of floating needles or metal rods.
Negative pressure
A pressure below that of the existing atmospheric pressure taken as a zero reference.
NEMA
ACRONYM - National Electrical Manufacturers Association.
NFPA
ACRONYM - National Fluid Power Association.
NL
ACRONYM - non-lubricated compressor.
NM³/HR
Unit of free air flow rate. Normal cubic meter per hour. The air in the following conditions:1.013 bar(a) of pressure; 0 degrees Celsius of temperature and 0% of relative humidity .
No load
The air compressor continues to run, usually at full RPM, but no air is delivered because the inlet is either closed off or modified, not allowing inlet air to be trapped.
Nominal efficiency
An arbitrary filter efficiency rating.
Nominal filter rating
Filter rating indicating the approximate particle size for which the majority will not pass through a given filter. It is generally interpreted as meaning that 85% of the particles of size equal to the nominal filter rating will be retained by the filter.
Nominal micron rating
A term that means that 98% of all particles larger than a stated micron size have been removed from the product being filtered through the filter element.
Noncondensables
Are those constituents in the suction gas that cannot be condensed to a liquid with the cooling medium available.
Noncooled compressor cylinders
Reciprocating type compressor used mainly in oil and gas field applications. The compressor cylinders operate at low compression ratios and experience small temperature rise.
Noncorrosive gas
Is one that does not attack normal materials of construction.
Nonlubricated compressor
A compressor designed to compress air or gas without contaminating the flow with lubricating oil. Piston rings and packing are usually made of TFE-based materials or carbon or other synthetic material that operate without lubrication.
Normal air
Is the term used for average atmospheric air at sea level in a temperature zone where it contains some moisture. It is defined in the ASME Test Code For Displacement Compressors as being at 14.696 psiA, 68 °F, 36% RH and weighing 0.075 lb/cu ft. The k value is 1.395.
Nozzle
A projecting aperture at the end of a tube, pipe etc. serving as an outlet for compressed air. Reduces the demand on the compressor by generating the highest thrust and volume for the lowest possible air consumption.
Nozzle (valves)
The stationary seating surface, the inlet of a valve.
NPT
ACRONYM - National Pipe Thread standard. A description of a specific pipe thread
NPTT
ACRONYM - National Pipe Thread tapered. A description of a specific pipe thread
O.D.
A measurement. Outside diameter.
OEM
Original equipment manufacturer.
Off gas
Air or vapor given off or expelled as a byproduct or result of an operation or treatment process.
Oil aerosol
A suspension of fine solid or liquid particles in a gas.
Oil bath filter
A labyrinth type filter having the active surfaces continuously splashed with oil. Most pollutants are absorbed by the oil which when circulated releases its pollutants, which sink by gravity to the bottom of the oil pan.
Oil free compressor
A positive displacement air compressor which has no oil injected into the compression chamber for lubrication, cooling or sealing
Oil system
Consists of a vessel which is a combination of oil sump and oil separator, an oil cooler and an oil filter.
Operating pressure
The gauge pressure at which a pressure vessel is maintained in normal operation.
Operating pressure burst
Above this pressure, the system may rupture or burst.
Orifice
An opening such as a hole or vent. An opening through which air can pass, or a restricted opening placed in a pipe line to provide a means of controlling or measuring flow.
OSHA
Occupational Safety and Health Administration.
Overhung type centrifugal compressor
A single inlet compressor with the impeller or impellers mounted on an extended shaft of the driver.
Overpressure accumulation
The permitted increase in pressure developed after the valve has opened. Usually expressed in percentage, ie.; 3% accumulation (A.S.M.E. Code, Section I). Flows through safety/relief valves are officially determined at these overpressure conditions.

P1
Measuring point for compressor acceptance test. Pressure at the compressor inlet flange.
P2
Measuring point for compressor acceptance test. Pressure at the compressor outlet flange.
P3
Measuring point for compressor acceptance test. Pressure before an orifice or nozzle, downstream of compressor discharge.
P4
Measuring point for compressor acceptance test. Distribution pressure (headers).
P5
Measuring point for compressor acceptance test. Pressure at the point of use.
Package power
The total power absorbed by a compressor, including the power absorbed by all pumps, fans, coolers and the like.
Palm coupling
A compressed air coupling commonly used on European rail and road vehicles to connect one vehicle to the next.

Particle density
An important parameter in establishing an entrained particle's potential to impinge on control surfaces and cause erosion.
Particulate type filter
A device designed to remove solids, such as dirt, scale, rust and other contaminants from the air system.
Paving breaker
A hand held pneumatic tool. Designed for light demolition work, digging, making holes etc.
PDP
Pressure dew point temperature (°C).
Pedestal type centrifugal compressor
A single inlet compressor with the impeller or impellers mounted on a shaft supported by two bearings in a pedestal, with the driver coupled to the compressor shaft.
Perfect intercooling
Is obtained when the gas is cooled to first stage inlet temperature following each stage of compression.
Performance curve
A plot of expected operating characteristics (e.g.., discharge pressure versus inlet capacity, shaft horsepower versus inlet capacity).
Permeability
The relationship of flow per unit area to differential pressure across a filter medium.
pH
Measure of alkalinity or acidity in water and water containing fluids. Can be used to determine the corrosion inhibiting characteristic in water based fluids. Typically, pH > 8.0 is required to inhibit corrosion of iron and ferrous alloys in water based fluids.
Pinion
The smaller of two mating or meshing gears; can be either the driving or the driven gear.
Piston displacement
Net volume actually displaced by the compressor piston at rated machine speed, generally expressed in cubic feet per minute (usually CFM). For multistage compressors, the piston displacement of the first stage only is commonly stated as that of the entire machine.
Pleated filter
A filter element whose medium consists of a series of uniform folds and has the geometric form of a cylinder, cone, disc, plate ... Synonymous with "convoluted" and "corrugated".
Pneumatic
Of, relating to, or using air. Moved by air pressure. Filled with compressed air.
Pneumatics
Engineering science pertaining to gaseous pressure and flow.
Pneumatic tools
Tools that operate by air pressure.
PNEUROP oxidation test (POT)
Is a standardized method to determine the carbon formation characteristics of compressor lubricants.
Point of use
A single outlet or limited number of outlets in a building used to connect tools or equipment to the air system.
Pore
A small channel or opening in a filter medium which allows passage of gas.
Positive displacement compressors
Compressors in which successive volumes of air or gas are confined within a closed space, and compressed. They may be either reciprocating or rotating. (Trap air and then squeeze it to the desired pressure).
Potential energy
is the energy a substance possesses because of its elevation above the earth (or above some other chosen datum plane). .
Pounds per square inch
PSI - Pounds per square inch.
Pour point
Is the temperature at which oil begins to flow under prescribed conditions.
Power theoretical
The mechanical power required to compress polytropically and to deliver, through the specified range of pressures, the gas delivered by the compressor.
Power wheel
A built in mechanical device to recover a portion of the power consumed by a constant speed centrifugal compressor when operating at reduced capacity or reduced pressure rise, or both.
PPB
A measurement. Parts per billion
PPM
A measurement. Parts per million
Precool
Pre-Cooling of intake air for compressors and Blowers.
Precooler
Is a heat exchanger located immediately preceding an ejector to condense and remove a portion of the vapor in the mixture and thus reduce the total lb/hr to be handled.
Pre open warn
An audible or visual discharge at a pressure slightly lower than the set pressure on a valve. Warns the operator that the valve is about to open.
Pressure
Force per unit area, usually expressed in pounds per square inch (PSI) or BAR.
Pressure absolute
The total pressure measured from absolute zero ( i.e., from an absolute vacuum).
Pressure back
The pressure encountered on the return side of a system.
Pressure cracking
The pressure at which a pressure operated valve begins to pass a gas.
Pressure critical
Is the saturation pressure at the critical temperature.
Pressure dew point
Is the temperature at which moisture begins to condense in a compressed air system.
Pressure discharge
Is the total gas pressure (static plus velocity) at the discharge port of the compressor. Velocity pressure is considered only with dynamic compressors.
Pressure drop
Resistance to flow. Defined as the difference in pressure upstream and downstream.
Pressure gauge
A device that indicates pressure differential above or below atmospheric pressure.
Pressure inlet
Is the total pressure (static plus velocity) at the inlet flange of the compressor.
Pressure pot
In spray painting applications, a sealed paint cup with a paint gun which puts a measured amount of air pressure into it. This then forces the paint to the gun for atomization.
Pressure range
Difference between minimum and maximum pressures for an air compressor. Also called cut in-cut out or load-no load pressure range.
Pressure rated
The qualified operating pressure which is recommended for a component or a system by the manufacturer.
Pressure regulating valve
A valve which enables pressure to be reduced, or kept constant at a desired level.
Pressure relief device
A device actuated by inlet static pressure and designed to open during an emergency or abnormal condition to prevent a rise of internal pressure in excess of a specified value.
Pressure rise
The difference between the discharge pressure and the intake pressure.
Pressure static
The pressure measured in a flowing stream (liquid or gas) in such a manner that no effect on the measurement is produced by the velocity of the stream.
Pressure system
The pressure which overcomes the total resistances in a system. It includes all losses as well as useful work.
Pressure total
The pressure that would be produced by stopping a moving stream of liquid or gas.
Pressure velocity
The total pressure minus the static pressure in an air or gas stream.
Preventive maintenance
Also known as PM, maintenance performed according to a fixed schedule involving the routine repair and replacement of machine parts and components.
Process
Occurs whenever the system undergoes either a change in state or an energy transfer at a steady stare.
Pseudo critical pressure
Is the saturation pressure at the critical temperature. It is the highest vapor pressure that the liquid can exert.
PSI
Pounds per square inch.
PSIA
Pounds per square inch, absolute.
PSID
Pounds per square inch, differential.
PSIG
Pounds per square inch, gauge. Pressure indicated by a pressure gauge.
Psychrometry
Has to do with the properties of air-water vapor mixtures in the atmosphere.
PTFE
Polytetrafluorethylene.
Pulsation damper
A small receiver fitted on the inlet or discharge of a reciprocating compressor. The device is designed to remove the resonance from the compressor thereby reducing noise.
Pumping
Is 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 surge.
Purge air
The portion of dry, full line pressure, compressed air taken from the drying side tower of a dual tower desiccant dryer system. Expanded to a very low pressure and passed across the wet desiccant to strip the moisture in the desiccant of the regenerating tower. In the case of an external blower type dryer, the purge air is atmospheric air compressed by a blower and heated by an external heater to strip moisture off a wet desiccant bed.

Qci
Measuring point for compressor acceptance test. Amount of condensate collected in the intercooler.
Qca
Measuring point for compressor acceptance test. Amount of condensate collected in the aftercooler.
Qcr
Measuring point for compressor acceptance test. Amount of condensate collected in the air receiver.
Quick coupler
A coupling device which consists of a spring loaded shutoff valve and a positive locking mechanism. It is used to connect tools, hoses and other accessories. Also known as Quick Disconnect.

Radial compressor
A compressor belonging to the group of dynamic compressors. Characterized by radial flow. (Centrifugal)
Rebound
The extension of an air actuator beyond its design height.
Receivers
Tanks used for the storage of air discharged from compressors. They serve also to damp discharge line pulsations.
Reciprocating compressors
Machines in which the compressing element is a piston having a reciprocating motion in a cylinder.
Recovery pressure
Is that pressure of either motive fluid or discharge at which an ejector returns to stable operation following a period of unstable operation due to having previously reached the breaking pressure. There are two recovery pressures, one for motive fluid and one for the discharge pressure.
Reduced pressure
Ratio of the pressure of a gas to its critical pressure, in like units.
Reduced temperature
Is the ratio in absolute units of the actual gas temperature to the critical temperature.
Refrigerant
Media of heat transfer in a refrigeration unit. R12 and R22 are commonly used refrigerants.
Refrigeration dryer
A device consisting of a heat transfer system, a moisture elimination system and a refrigeration system designed to improve the quality of the air and reduce the temperature of the air.
Regeneration
The process of desiccants being regenerated by water being driven off the desiccant. Hot air or gas passes through the desiccant bed, heating it. As a result, the partial pressure of the water vapor becomes higher than that in the regenerating air. Water is therefore released from the desiccant and carried away with the air stream (purge air) until a new state of equilibrium is reached.
Regulator
An automatic or manual device designed to control pressure, flow or temperature.
Reheaters
Heat exchangers for raising the temperature of compressed air to increase its volume.
Relative clearance volume
The ratio of clearance volume to the volume swept by the compressing element.
Relative humidity
The ratio of the actual water-vapor partial pressure to its saturation pressure at the same temperature. (considered only with atmospheric air).
Relative vapor pressure
The ratio of the vapor pressure to the saturated vapor pressure at the temperature considered.
Relief valve
A spring loaded pressure relief valve actuated by the static pressure upstream of the valve. The valve opens normally in proportion to the pressure increase over the opening pressure.
Required capacity
Cubic feet per minute (cfm) of air required at the inlet to the distribution system.
Reversible process
is an ideal process that may be stopped and made to retrace its steps and restore to the systems or surroundings all work and heat previously removed. It is frictionless.
Reynold's number
A dimensionless flow parameter, ( Jnr/m), in which J is a significant dimension, often a diameter, n is the fluid velocity, r is mass density, and m is dynamic viscosity, all in consistent units.
Rings
Circular metallic elements that ride in the grooves of a piston and provide compression sealing during combustion. Also used to spread oil for lubrication.
Ring sticking
freezing of a piston ring in its groove in a piston engine or reciprocating compressor due to heavy deposits in the piston ring zone.
Rock drill
A pneumatic percussive drill designed as a boring tool.
Rolling element
A type of journal bearing in centrifugal air compressors.
Rotary actuator
A pneumatic device with a rotary output. Typically of a vane or rack-and-pinion construction.
Rotary blowers
A compressor belonging to the group of displacement rotary compressors, a type of valve less displacement machine. Also referred to as "Roots blower".
Rotary compressors
Machines in which compression is effected by the positive action of rotating elements.
Rotary sliding vane compressors
Machines in which axial vanes slide radially in an eccentrically mounted rotor.
Rotor
The rotating element of a machine and, in the case of a compressor, is composed of the impeller (impellers) and shaft, and may include shaft sleeves and a thrust balancing device.
Rust prevention test
(turbine oils) -- a test for determining the ability of an oil to aid in preventing the rusting of ferrous parts in the presence of water.

 

[Klavyeah]

SAE
Society of Automotive Engineers.
Safety valve
A device that limits fluid (liquid and gaseous) pressures by discharging some of the pressurized liquid or gas.
Safety relief valve
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.
Saturated air vapor mixture
Is one in which the space occupied by the mixture is saturated with water vapor at the mixture temperature.
Saturated vapor pressure
Is 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.
Saturation
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.
Saturation pressure
Is another term for saturated vapor pressure.
Scale
A coating or precipitate deposited on surfaces such as water pipes, 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.
SCFM
Standard cubic feet per minute., SCFM or scfm. 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.) Scfm means cfm at standard conditions. However, standards vary and some care is necessary. In the United states, 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 that the reference pressure and temperature be definitely specified.
Screw compressor
Is a positive displacement rotary compressor.
SCUBA
Self Contained Underwater Breathing Apparatus
Sea level
This is the average level of the ocean over the entire earth., tidal fluctuation is taken into account when determining sea level.
Seals
Devices used between rotating and stationary parts to separate, and minimized leakage between, areas of unequal pressures.
Seat
The stationary seating surface, the inlet of a valve.
Second law of thermodynamics
Heat cannot, of itself, pass from a colder to a hotter body.
Sequence
The order in which compressors are brought online.
Set pressure
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.
Shaft
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.
Shaft input
The power required at the compressor drive shaft. Losses in external transmissions such as gears and belt drives are not included.
Shaft sleeves
Devices that may be used to position the impeller or to protect the shaft.
Shaft speed irregularity
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.
SI
Systeme International. The international system of unit measurement.
Single acting
The piston only compresses air with its stroke in one direction.
Single stage compressors
Machines in which air or gas is compressed in each cylinder or casing from initial intake pressure to final discharge pressure.
Silica gel
A desiccant most commonly used in heat regenerative type dryers.
Single stage centrifugal compressors
Machines having only one impeller.
Siphon feed gun
Any paint gun which uses air flowing over an opening to create a vacuum to draw paint up a tube to be atomized.
Sleeve
A type of journal bearing in centrifugal air compressors.
Slip
Is 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.
Slip RPM
Is the speed required of a rotary compressor to maintain a given discharge pressure, supplying leakage only (zero actual output). It is an experience factor.
Sludge
A soft, black, mayonnaise-like deposit which is typically an emulsion of oil, water, and oil insolubles.
Slusher
An air operated device for hoisting or pulling. Similar to a winch
Sole plate
A metallic pad, usually embedded in concrete, on which the compressor feet are mounted.
Sonic flow
The point (speed of sound) at which air flow through an orifice can not increase regardless of pressure drop.
SOP
Standard operating procedures for the production, purification, storage and distribution of compressed breathing air.
SPC
Specific Power Consumption.
Specific energy requirement
The shaft input per unit of compressor capacity.
Specific fuel consumption
The ratio of fuel consumption to compressor capacity.
Specific gravity
This property is the ratio of the specific weight of air or gas to that of dry air at the same pressure and temperature.
Specific heat
The quantity of heat required to raise the temperature of a unit weight of a substance by one degree.
Specific humidity
The weight of water vapor in an air-vapor mixture per pound of dry air.
Specific power
A measure of air compressor efficiency, usually in the form of bhp/100 acfm or acfm/bhp
Specific volume
Is the volume of a given weight of gas, usually expressed as cu ft/lb as SPT conditions.
Specific weight
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.
Speed
The number of revolutions per minute of the compressor shaft.
Spindle
The rod connecting the disc to the lever on a valve.

SRM
Screw compressor development center. Licensor to 90% of twin screw compressor market.

Stability
Stability is 100 minus the surge limit at rated discharge pressure, where the surge limit is expressed in percentage of rated capacity.
Stack up
The interaction between the stages of a centrifugal compressor. When a multi-stage compressor is designed, each stage can operate at only one point 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.
Stages
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.
Standard air
Air at a temperature of 68 °F, a pressure of 14.70 psia and a relative humidity of 36 per cent (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)
Standard pressure and temperature (SPT)
See standard air.
Start stop control (SPT)
A system in which air supply is matched to demand by the starting and stopping of the unit.
State
Of a system (or part thereof) is its condition at an instant of time as described or measured by its properties.
Stem
The rod connecting the disc to the lever on a valve.
Sterile air
Free from living organisms and especially micro-organisms. Usually used in food and dairy applications.
Stonewall
The unstable operation of a centrifugal compressor below the design point of the compressor.
STP
Standard pressure and temperature. See standard air.
Strainer
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.
Stroke total
The difference between the maximum extended height and the compressed height of an air actuator.
Stroke usable
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.
Subheaders
Are the connections between the headers and the work station.
Suction pressure
This is the pressure found on the suction side of a refrigeration system.
Supercompressibility factor
This is a factor expressing deviation of a gas from perfect gas laws.
Surface filtration
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.
Surge
Is 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.
Surge limit
In a dynamic compressor, surge limit is the capacity below which the compressor operation becomes unstable.
Swept volume
term mainly used by companies selling small compressors because it makes their compressors look bigger than they really are. The swept volume is the actual displacement of the piston, forgetting such losses as bumping clearances, valve clearances, ring losses and the like. It's not unusual to see an advertisement offering a compressor with (say) a delivery of 30 cfm, swept. In reality the compressor will only deliver about 20 scfm..
Synthetic lubricant
A lubricating oil made with synthetic base stocks.

T1
Measuring point for compressor acceptance test. Temperature at the compressor inlet flange.
T3
Measuring point for compressor acceptance test. Temperature before an orifice or nozzle, downstream of compressor discharge.
Temperature
Is the property of a substance that gauges the potential or driving force for the flow of heat.
Temperature absolute
The temperature of a body referred to the absolute zero, at which point the volume of an ideal gas theoretically becomes zero. (Fahrenheit scale is minus 459.67°F / Celsius scale is minus 273.15°C).
Temperature discharge
Is the temperature existing at the discharge port of the compressor.
Temperature inlet
Is the temperature at the inlet flange of the compressor.
Temperature intake
The toal temperature at the intake flange of the compressor.
Temperature rise ratio
Is the ratio of the computed isentropic temperature rise to the measured total temperature rise during compression.
Temperature static
The actual temperature of a moving gas stream. It is the temperature indicated by a thermometer moving in the stream with the same velocity as the stream.
Temperature total
The temperature which would be measured at the stagnation point if a gas stream were stopped, with adiabatic compression from the flow condition to the stagnation pressure.
Theoretical power
The power required to compress a gas isothermally through a specified range of pressures.
Thermal compressor
is an ejector used to compress waste or exhaust steam or any other gas through a moderate range of compression above atmospheric pressure.
Thermal mass
Material that stores energy, although mass will also retain coolness. The thermal storage capacity of a material is a measure of the material's ability to absorb and store heat.
Thermodynamics first law of
The amount of work done on or by a system is equal to the amount of energy transferred to or from the system.
Thermodynamics second law of
Heat cannot, of itself, pass from a colder to a hotter body.
Thrust balancing device
The part of a rotating element that counteracts any inherent thrust developed by the impellers.
Tilting pad
A type of journal bearing in centrifugal air compressors.
Torr
A unit of pressure used with vacuum pumps, equal to 1mm of mercury and 133.32 Pascal's.
Total package input power
The total electrical power input to a compressor, including drive motor, cooling fan, motors, controls, etc.
Torque
Torsional moment or couple. It usually refers to the driving couple of a machine or motor.
Trunk compressor
A compressor belonging to the group of displacement reciprocating compressors.
Trunnion
A device for mounting cylinders.
Tugger
An air operated device for hoisting or pulling. Similar to a slusher or winch
Tundish
A receptacle, open to atmosphere, that is used to used to collect condensate. For example, two or three drain pipes from various filters may be discharging into a funnel. In this case the funnel is a tundish.
Two stage compressor
Machines in which air or gas is compressed from initial pressure to an intermediate pressure in one or more cylinders or casings.
Two step control
Load/unload control system that tries to maximizes compressor efficiency by matching air delivery and air demand. Compressor is operated at full load or idle
TXV valve
A thermal expansion valve.

UL
Underwriters Lab.
Ultrasonic leak detector
An instrument designed to detect the ultrasonic emissions and convert them to audible signal.
UNC
Thread - Unified national coarse.
UNF
Thread - Unified national fine.
Unit type compressors
Compressors of 20 HP or less, generally combined with all the components required to put the into operation.
Unload
The air compressor continues to run, usually at full RPM, but no air is delivered because the inlet is either closed off or modified, not allowing inlet air to be trapped.
Unloaded horsepower
The power that is consumed to overcome the frictional losses when operating in an unloaded condition.
Utilization factor
The ratio in percentage of the time that the equipment is in operation to the total working time.

Vacuum pumps
Compressors that operate with an intake pressure below atmospheric and discharge pressure usually atmospheric or slightly higher.
Valves
Devices with passages for directing flow into alternate paths.
Vane compressor
Is a single shaft, positive displacement rotary compressor.
Vane material
Most common material is phenolic resin-impregnated laminated fabrics, such as asbestos or cotton cloth. For oil free service, bronze and carbon/graphite vanes are used.
Vapor
Fine separated particles floating in the air and clouding it. A substance in the gaseous state.
Vapor pressure
Is the pressure exerted by a vapor confined within a given space. The vapor may be the sole occupant of the space, or may be associated with other gases.
Varnish
The oxidation of conventional hydrocarbon lubricants when they reach the end of their useful life and begin to breakdown. Can cause operating temperature increase, increase brake horsepower and plugs separator, can destroy air end.
V belt drive
A drive arrangement for power transmission to compressors.
Venturi
A tube with a narrow throat (a constriction) that increases the velocity and lowers the pressure of the liquid passing through it, creating a partial vacuum immediately after the constriction in the tube. The vacuum created has a sucking effect, and a venturi is commonly used to introduce a liquid (such as a regenerant) or gas (such as air) into a flowing water stream.
Viscosity
Is a measure of resistance to deformation, or reluctance to be squeezed out a bearing. Indicates the internal friction of a fluid. Viscosity in normal lubricants is reduced as temperature increases
Viscosity index (VI)
Is a measure of the rate of change of viscosity with temperature. Oils with high VI have low viscosity changes.
Volumetric efficiency
The ratio and percent of the actual delivered capacity (measured at inlet temperature, pressure and gas composition) to the piston displacement.
Volute
A stationary, spirally shaped passage that converts velocity head to pressure.
Voting alarm
(Compressors/Gas Turbines) Is an alarm system that has maybe 3 sensors connected to it and it will require minimum of 2 of the 3 to alarm before the alarm will act. There is a controller connected that does the logic decision based on set parameters.
Warn
The control ring in a valve which surrounds the seat, used to control pre open and blow down.
Water cooled compressors
Machines cooled by water circulated through jackets surrounding the cylinders or casings.
Wet bulb temperature
Is used in psychrometry and is the temperature recorded by a thermometer whose bulb has been covered with a wetted wick and whirled on a sling psychrometer. Taken with the dry bulb, it permits determination of relative humidity of the atmosphere.
Wet gas
Is any gas or gas mixture in which one or more of the constituents is at its saturated vapor pressure. The constituent at saturation pressure may or may not be water vapor.
Wet helical lobe unit
Is one which 1) handles a small constant flow of liquid with the gas; 2) utilizes evaporative (injection) cooling; or 3) circulates a liquid for sealing and/or cooling. The last may or may not be evaporative cooling.
Wicking
The vertical absorption of a liquid into a porous material by capillary forces.
Winch
An air operated device for hoisting or pulling. Similar to a slusher or tugger
WMW
Welded Minimum Wall tubing
WOG
WOG - A pressure rating in psi for valves. W. Water, O. Oil, G. Gas
Work
Is energy in transition and is defined in units of Force times Distance. Work cannot be done unless there is movement.
Working pressure
The normal working pressure for an air motor (6 bar).
Xenon
An inert gaseous element.
Yoke
The portion of a safety/relief valve that surrounds the spring. The spring housing.
ZDDP
an antiwear additive found in many types of hydraulic and lubricating fluids. Zinc dialkyldithiophosphate.
Zero
The temperature of pure melting ice under standard atmospheric pressure on the Centigrage and Réaumur scales.
Zero discharge water
A discharge limit applied to manufacturing and commercial establishments in which only normal human sanitary wastewaters may be discharged to the municipal sewerage system. All other types of wastewater, such as that water used in manufacturing processes, are not included in zero discharge water; these wastewaters must be recycled, and the resulting waste products must be taken to an alternate and approved disposal facility.

 

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