MOST COMMON ISSUES WITH AIR COMPRESSORS
TROUBLESHOOTING AIR COMPRESSOR PROBLEMS
WWW.HKAIRCOMPRESSORS.COM
214-428-2868
| MOTOR ISSUES | Power not on | Turn power on |
| MOTOR ISSUES | Blown main fuses (size 175% of motor nameplate) | Replace fuses |
| MOTOR ISSUES | Blown control fuses (size per nec article 450-3) | Replace fuses |
| MOTOR ISSUES | Breaker tripped | Reset or replace breaker |
| MOTOR ISSUES | Safety device tripped | Reset safety devices |
| MOTOR ISSUES | Motor starter overloads tripped | Reset or replace overloads |
| MOTOR ISSUES | Faulty motor starter coil | Replace starter coil |
| MOTOR ISSUES | Pressure switch incorrectly set | Adjust pressure switch |
| MOTOR ISSUES | Pressure switch defective | Replace pressure switch |
| MOTOR ISSUES | Start switch contacts defective | Replace start switch |
| MOTOR ISSUES | Auxiliary contacts defective | Replace Auxiliary |
| MOTOR ISSUES | Loose electrical wire | Tighten electrical wires |
| MOTOR ISSUES | Wire broken or off terminal | Replace wire or reconnect |
| MOTOR ISSUES | Thermal overload inside motor tripped | Reset or replace motor |
| MOTOR ISSUES | Low voltage | Must be 10 % of nameplate |
| MOTOR ISSUES | Motor defective | Replace motor |
| MOTOR ISSUES | Wiring incorrect | Correct wiring |
| STARTER TRIPS | Low voltage (must be within 10% of nameplate | Check voltage @ disconnect |
| STARTER TRIPS | Wrong heater size (check heater amps) | Replace heaters elements |
| STARTER TRIPS | Wrong overload setting (check motor amps) | Adjust overload setting |
| STARTER TRIPS | Loose electrical connection | Tighten all wire connections |
| STARTER TRIPS | Wire size too small | Install correct size wire |
| STARTER TRIPS | Motor defective | Replace motor |
| STARTER TRIPS | Motor sized incorrectly | Resize & replace motor |
| STARTER TRIPS | Pressure switch unloader defective | Replace pressure switch |
| STARTER TRIPS | Centrifugal Unloader valve defective | Replace valve |
| STARTER TRIPS | Electric solenoid unloader valve defective | Replace valve |
| STARTER TRIPS | Hydraulic unloader valve defective | Replace valve |
| STARTER TRIPS | In-tank check valve defective | Replace valve |
| STARTER TRIPS | Unloaders not unloading suction valves | Check for pressure / rebuilt |
| STARTER TRIPS | Defective compressor valves | Replace compressor valves |
| STARTER TRIPS | Unloader control line plugged | Replace control line |
| STARTER TRIPS | Discharge pressure too high | Adjust switch or replace |
| STARTER TRIPS | Drive belts too tight | Adjust to correct tension |
| STARTER TRIPS | Head gasket blown between the cylinders | Replace head gasket |
| STARTER TRIPS | No crankshaft endplay (.001 per inch of bearing od) | Adjust bearings tolerance |
| STARTER TRIPS | Rod bearing tight or seizing (.001 per inch diameter) | Replace bearings or rods |
| STARTER TRIPS | Pistons seizing to cylinders | Replace pistons / rebuilt |
| STARTER TRIPS | Incorrect oil | Change to correct weight |
| STARTER TRIPS | Intercooler plugging (30-50) psig normal | Remove clean or replace |
| STARTER TRIPS | Compressor unit seized (locked up) | Remove & disassemble unit |
| PRESSURE SWITCH | Moisture build up on the switch diaphragm | Replace pressure switch |
| PRESSURE SWITCH | Ruptured diaphragm (air leak) | Replace pressure switch |
| PRESSURE SWITCH | Burned contact points | Replace pressure switch |
| PRESSURE SWITCH | Unloader valve leaking (when running) | Replace pressure switch |
| PRESSURE SWITCH | Pressure setting changes | Replace pressure switch |
| PRESSURE SWITCH | Plugged air passage in unloader valve | Replace pressure switch |
| PILOT VALVE UNLOADER | Pilot valve unloader unloads at to low or high pressure | Adjust pilot unloader valve |
| PILOT VALVE UNLOADER | Pilot valve unloader loads/unloads excessively | Adjust pilot unloader valve |
| PILOT VALVE UNLOADER | Pilot valve unloader leaking when running | Replace pilot unloader valve |
| PILOT VALVE UNLOADER | Pilot valve unloader leaking when stopped | Replace pilot unloader valve |
| SOLENOID | Solenoid leaking @ exhaust port when stopped | Replace electric solenoid valve |
| SOLENOID | Solenoid leaking @ cylinder port when running | Replace electric solenoid valve |
| SOLENOID | Solenoid does not click when electricity is applied | Replace electric solenoid valve |
| CENTRIFUGAL UNLOADER | Centrifugal Unloader valve leaking when running | Adjust or replace unloader |
| CENTRIFUGAL UNLOADER | Centrifugal Unloader valve leaking when stopped | Replace in-tank check valve |
| HYDRAULIC UNLOADER | Hydraulic unloader valve passes air to suction | Adjust oil pressure to 25 psig |
| HYDRAULIC UNLOADER | unloader when running oil pressure less than 15 psig | |
| HYDRAULIC UNLOADER | Hydraulic unloader valve passes air to suction | Replace hydraulic unloader |
| HYDRAULIC UNLOADER | unloader when running with 25 psig oil pressure | |
| HYDRAULIC UNLOADER | Hydraulic unloader passes no air to suction unloader when not running | Replace hydraulic unloader |
| INTERCOOLER SAFETY | Safety Relief valve defective (set 45-100 psig ) | Replace Safety relief valve |
| INTERCOOLER SAFETY | Relief Valve pops off when running & pumping | Replace unloaders or valves |
| INTERCOOLER SAFETY | Valve pops off when running & not pumping | Replace unloaders or valves |
| INTERCOOLER SAFETY | Valve pops off when not running | Replace unloaders or valves |
| INTERCOOLER SAFETY | Intercooler restricted or plugged | Clean or replace intercooler |
| INTERCOOLER PRESSURE | Defective pressure gauge | Replace air pressure gauge |
| INTERCOOLER PRESSURE | Leaking intercooler connections | Tighten connection |
| INTERCOOLER PRESSURE | Leaking intercooler | Replace intercooler |
| INTERCOOLER PRESSURE | Compressor valves in L.P. defective | Replace valves |
| INTERCOOLER PRESSURE | Suction Unloaders in L.P. defective | Rebuild or replace |
| INTERCOOLER PRESSURE | Restricted air inlet filter | Replace inlet filter |
| INTERCOOLER PRESSURE | Compressor valve defective | Replace compressor valves |
| INTERCOOLER PRESSURE | Pilot valve defective | Replace pilot valve |
| INTERCOOLER PRESSURE | Hydraulic valve not functioning properly | Replace hydraulic unloader |
| INTERCOOLER PRESSURE | Electric solenoid valve not functioning properly | Replace solenoid valve |
| INTERCOOLER PRESSURE | Worn piston rings | Replace piston rings |
| DISCHARGE SAFETY | Relief valve defective (set 150% of tank psig) | Replace relief valve |
| DISCHARGE SAFETY | Restricted in-tank check valve | Replace check valve |
| DISCHARGE SAFETY | Restricted discharge pipe | Clean or replace pipe |
| EXCESSIVE AIR | Air pressure gauge inaccurate | Replace air pressure gauge |
| RECEIVER | Leaks in unloader piping system | Repair leaks in control piping |
| RECEIVER | Defective compressor suction unloaders | Repair or replace unloader |
| RECEIVER | Pilot valve set incorrectly or defective | Adjust or replace valve |
| RECEIVER | Pressure switch set incorrectly or defective | Adjust or replace switch |
| RECEIVER | Pressure switch wired incorrectly | Correct wiring |
| RECEIVER | Hydraulic valve not functioning properly | Replace hydraulic valve |
| RECEIVER | Electric solenoid valve not functioning properly | Replace solenoid valve |
| RECEIVER | Tube to compressor unloader valve plugged | Replace control air line |
| BUILDING PRESSURE TOO FAST | Air pressure gauge inaccurate | Replace air pressure gauge |
| BUILDING PRESSURE TOO FAST | Tank full of water | Drain water from tank |
| SLOW TANK PRESSURE RAISING | Defective pressure gauge | Replace pressure gauge |
| SLOW TANK PRESSURE RAISING | Restricted air inlet filter | Replace inlet filter |
| SLOW TANK PRESSURE RAISING | Pressure switch defective | Replace pressure switch |
| SLOW TANK PRESSURE RAISING | Pressure switch set wrong | Adjust pressure switch |
| SLOW TANK PRESSURE RAISING | Unloader pilot defective | Replace pilot valve |
| SLOW TANK PRESSURE RAISING | Unloader pilot set wrong | Adjust pilot valve |
| SLOW TANK PRESSURE RAISING | Faulty hydraulic unloader | Replace hydraulic unloader |
| SLOW TANK PRESSURE RAISING | Electric solenoid valve not functioning properly | Replace solenoid valve |
| SLOW TANK PRESSURE RAISING | Centrifugal Unloader valve leaking when running | Replace centrifugal valve |
| SLOW TANK PRESSURE RAISING | Defective compressor valves | Replace compressor valves |
| SLOW TANK PRESSURE RAISING | Leaking head gasket | Replace head gasket |
| SLOW TANK PRESSURE RAISING | Loose compressor valves leaking at valve gaskets | Replace valve gasket |
| SLOW TANK PRESSURE RAISING | Low oil pressure | Adjust oil pressure |
| SLOW TANK PRESSURE RAISING | Drive belt slipping | Adjust belt tension |
| SLOW TANK PRESSURE RAISING | Incorrect speed | Change motor pulley |
| SLOW TANK PRESSURE RAISING | Clogged intercooler (internal) | Clean or replace |
| SLOW TANK PRESSURE RAISING | Excessive running clearances | Rebuilt compressor pump |
| SLOW TANK PRESSURE RAISING | Worn piston rings or loose piston | Rebuilt compressor pump |
| SLOW TANK PRESSURE RAISING | Leaks in the compressed air distribution system | Find & Repair air leaks |
| SLOW TANK PRESSURE RAISING | Drain valve open | Close drain valve |
| SLOW TANK PRESSURE RAISING | Pressure relief valve leaking | Replace relief valve |
| SLOW TANK PRESSURE RAISING | Compressor incorrectly sized for the altitude | Install larger compressor |
| LOADING AND UNLOADING | Pressure switch defective | Replace pressure switch |
| LOADING AND UNLOADING | Pilot valve set incorrectly or defective | Replace pilot valve |
| LOADING AND UNLOADING | Electric solenoid valve not functioning properly | Replace solenoid valve |
| LOADING AND UNLOADING | Compressor valves defective | Replace compressor valves |
| LOADING AND UNLOADING | Suction unloaders leaking | Repair leaking unloader |
| LOADING AND UNLOADING | Compressor operating at incorrect speed | Install correct pulley |
| LOADING AND UNLOADING | Excessive system leakage | Repair air leaks |
| LOADING AND UNLOADING | Air receiver tank too small | Install larger receiver tank |
| LOW OIL PRESSURE | Defective pressure gauge | Replace oil gauge |
| LOW OIL PRESSURE | Low oil level | Add oil to full mark |
| LOW OIL PRESSURE | Oil pump direction reversed | Change rotation |
| LOW OIL PRESSURE | Oil sump strainer plugged | Clean or replace strainer |
| LOW OIL PRESSURE | Plugged oil filter | Replace oil filter |
| LOW OIL PRESSURE | Leakage at mains & rod bearings | Rebuilt compressor pump |
| LOW OIL PRESSURE | Oil pressure adjusting screw not set properly | Adjust oil pressure to spec |
| USING TOO MUCH OIL | Compressor runs unloaded too long | Run in start/stop position |
| USING TOO MUCH OIL | Worn piston rings | Replace ring |
| USING TOO MUCH OIL | Restricted intake system | Replace inlet filter |
| USING TOO MUCH OIL | Compressor running too hot | See high discharge temp |
| USING TOO MUCH OIL | Breather valve not functioning properly | Replace breather valve |
| USING TOO MUCH OIL | Oil level in crankcase too high | Drain to proper oil level |
| USING TOO MUCH OIL | Oil viscosity wrong for the application | Change to correct viscosity |
| USING TOO MUCH OIL | Connecting rod out of alignment, bent or twisted | Replace connecting rods |
| USING TOO MUCH OIL | Leaking oil seal | Replace shaft oil seal |
| USING TOO MUCH OIL | Piston rings not seated (300 hours for seating) | Change to non detergent oil |
| USING TOO MUCH OIL | Wrong oil ( detergent oil has a tendency to foam) | Use air compressor oil |
| HIGH DISCHARGE TEMP. | Defective temperature gauge or switch | Replace temp gauge or switch |
| HIGH DISCHARGE TEMP. | Compressor valve assemblies defective | Replace compressor valves |
| HIGH DISCHARGE TEMP. | Pulley/sheave rotation wrong | Change rotation |
| HIGH DISCHARGE TEMP. | Discharge pressure too high | Adjust pressure lower |
| HIGH DISCHARGE TEMP. | Ambient temperature too high | Lower ambient temperature |
| HIGH DISCHARGE TEMP. | Inadequate ventilation or hot air recirculating | Vent hot air out of room |
| HIGH DISCHARGE TEMP. | Cooling surfaces of compressor excessively dirty | Clean cooling fins |
| HIGH DISCHARGE TEMP. | Intercooler excessively dirty internal or external | Clean internal & external |
| HIGH DISCHARGE TEMP. | Defective water temperature regulating valve | Replace water regulating val |
| HIGH DISCHARGE TEMP. | Clogged water passages in head &/or cylinders | Clean water passages |
| HIGH DISCHARGE TEMP. | Inadequate cooling water flow | Increase water flow |
| HIGH DISCHARGE TEMP. | Cooling water temperature too hot | Lower temperature of water |
| HIGH DISCHARGE TEMP. | Lubrication inadequate | Use air compressor oil |
| HIGH DISCHARGE TEMP. | Running clearances insufficient | Change clearances |
| HIGH DISCHARGE TEMP. | Scored or excessively worn cylinder walls | Replace cylinder |
| KNOCKING | Incorrect speed | Change motor pulley |
| KNOCKING | Compressor incorrectly size | Install larger compressor |
| KNOCKING | Loose belts | Adjust belts |
| KNOCKING | Head clearance insufficient | Check piston to head clearance |
| KNOCKING | Piston loose in cylinder bore worn piston rings | Rebuilt compressor pump |
| KNOCKING | Worn rods or main bearing | Rebuilt compressor pump |
| KNOCKING | Pressure setting excessive high | Adjust to lower pressure |
| KNOCKING | Crankcase lubrication inadequate | Correct lubrication problem |
| KNOCKING | Loose pulley/sheave | Tighten pulley & sheave |
| KNOCKING | Compressor valve assemblies loose | Tighten compressor valves |
| KNOCKING | Loose compressor or motor mounting bolts | Tighten mounting bolts |
| KNOCKING | In-tank check defective | Replace check valve |
| EXCESSIVE BELT WEAR | Pulley/sheave out of alignment | Realign pulley & sheave |
| EXCESSIVE BELT WEAR | Belt too loose or too tight | Adjust to correct tension |
| EXCESSIVE BELT WEAR | Belt slipping | Replace belts |
| EXCESSIVE BELT WEAR | Pulley/sheave wobbling | Tighten to shafts |
| EXCESSIVE BELT WEAR | Pulley/sheave groove damaged or worn | Replace pulley & sheave |
| EXCESSIVE BELT WEAR | Incorrect belts | Replace with correct belts |
| EXCESSIVE VIBRATION | Compressor feet not level | Shim compressor feet |
| EXCESSIVE VIBRATION | Compressor tightened into a bind | Retighten & shim |
| EXCESSIVE VIBRATION | Motor or engine not secured tightly | Tighten motor secure |
| EXCESSIVE VIBRATION | Foundation or frame inadequate | Install correct foundation |
| EXCESSIVE VIBRATION | Piping inadequately supported | Install additional support |
| EXCESSIVE VIBRATION | Piping tightened into a bind | Install flexiblemetal hose |
| EXCESSIVE VIBRATION | Excessive discharge pressure | Lower pressure setting |
| EXCESSIVE VIBRATION | Loose pulley/sheave | Tighten pulley & sheave |
| EXCESSIVE VIBRATION | Incorrect speed | Change to correct rpms |
| EXCESSIVE VIBRATION | Compressor valves not functioning properly | Replace compressor valves |
| EXCESSIVE VIBRATION | Motor or engine out of balance | Balance motor or engine |
| RUSTY VALVES/CYCLINDERS | Compressor operated too infrequently | Run compressor more |
| RUSTY VALVES/CYCLINDERS | Compressor does not run long enough to get hot | Install smaller compressor |
| RUSTY VALVES/CYCLINDERS | Leaking water jacket or cylinder head | Repair water leak |
| RUSTY VALVES/CYCLINDERS | Cooling water circulating in compressor too cold | Replace water regulator valve |
| RUSTY VALVES/CYCLINDERS | System pressure leaking back through compressor | Re-pipe & add a check valve |
| WATER IN CRANKCASE | Compressor does not run long enough to get hot | Install smaller compressor |
| MILKY OIL | System pressure leaking back through compressor | Re-pipe & add a check valve |
| MILKY OIL | Leaking water jacket or cylinder head | Repair water leak |
| MILKY OIL | Cooling water circulating in compressor too cold | Replace water regulator valve |
| MILKY OIL | Incorrect or inferior grade of lubricant | Use air compressor oil |
AIR COMPRESSOR SERVICE AND REPAIR
WWW.HKAIRCOMPRESSORS.COM
214-428-2868
visit: www.cagi.org
Absolute Temperature - See Temperature, Absolute. https://www.cagi.org/
Absorption - The chemical process by which a hygroscopic
desiccant, having a high affinity with water, melts and becomes a liquid by
absorbing the condensed moisture.
Actual Capacity - Quantity of gas actually compressed and
delivered to the discharge system at rated speed and under rated conditions.
Also called Free Air Delivered (FAD).
Adiabatic Compression - See Compression, Adiabatic. https://www.cagi.org/
Adsorption - The process by which a desiccant with a
highly porous surface attracts and removes the moisture from compressed air.
The desiccant is capable of being regenerated.
Air Receiver - See Receiver. https://www.cagi.org/
Air Bearings - See Gas Bearings. https://www.cagi.org/
Aftercooler - A heat exchanger used for cooling air
discharged from a compressor. Resulting condensate may be removed by a moisture
separator following the aftercooler.
Ambient Temperature - the temperature of the surrounding
environment; technically, the temperature of the air surrounding a power supply
or cooling medium; abbreviated [ABM]
Atmospheric Pressure - The measured ambient pressure for a
specific location and altitude.
Automatic Sequencer - A device which operates compressors in
sequence according to a programmed schedule.
CFM - The amount of air flow delivered under
specific conditions, usually expressed in cubic feet per minute (cfm).
Capacity, Actual - The actual volume flow rate of air or gas
compressed and delivered from a compressor running at its rated operating
conditions of speed, pressures, and temperatures. Actual capacity is generally
expressed in actual cubic feet per minute (acfm) at conditions prevailing at
the compressor inlet.
Capacity Gauge - A gauge that measures air flow as a
percentage of capacity, used in rotary screw compressors
Check Valve - A valve which permits flow in only one
direction.
Clearance - The maximum cylinder volume on the working
side of the piston minus the displacement volume per stroke. Normally it is
expressed as a percentage of the displacement volume.
Clearance Pocket - An auxiliary volume that may be opened to
the clearance space, to increase the clearance, usually temporarily, to reduce
the volumetric efficiency of a reciprocating compressor.
Compressibility - A factor expressing the deviation of a gas
from the laws of thermodynamics. (See also Super compressibility)
Compression, Adiabatic - Compression in which no heat is transferred
to or from the gas during the compression process.
Compression,
Isothermal - Compression is
which the temperature of the gas remains constant.
Compression,
Polytropic - Compression in
which the relationship between the pressure and the volume is expressed by the
equation pvn is a constant.
Compression Ratio - The ratio of the absolute discharge
pressure to the absolute inlet pressure.
Constant Speed Control - A system in which the compressor is run
continuously and matches air supply to air demand by varying compressor load.
Critical Pressure - The limiting value of saturation pressure
as the saturation temperature approaches the critical temperature.
Critical Temperature - The highest temperature at which
well-defined liquid and vapor states exist. Sometimes it is defined as the
highest temperature at which it is possible to liquefy a gas by pressure alone.
Cubic Feet Per Minute
(cfm) - Volumetric air flow
rate. https://www.cagi.org/
cfm, free Air - cfm of air delivered to a certain point at
a certain condition, converted back to ambient conditions.
Actual cfm (acfm) - Flow rate of air at a certain point at a
certain condition at that point.
Inlet cfm (icfm) - Cfm flowing through the compressor inlet
filter or inlet valve under rated conditions.
Standard cfm (scfm) - Flow of free air measured and
converted to a standard set of reference conditions (14.5 psia, 68ºF, and 0%
relative humidity).
Cut-In/Cut-Out Pressure - Respectively, the minimum and maximum discharge pressures at which the compressor will switch from unload to load operation (cut in) or from load to unload (cut out).
Cut-In/Cut-Out Pressure - Respectively, the minimum and maximum discharge pressures at which the compressor will switch from unload to load operation (cut in) or from load to unload (cut out).
Cycle - The series of steps that a compressor with
unloading performs; 1) fully loaded, 2) modulating (for compressors with
modulating control), 3) unloaded, 4) idle.
Cycle Time - Amount of time for a compressor to complete
one cycle.
Degree
of Intercooling - The difference in
air or gas temperature between the outlet of the intercooler and the inlet of
the compressor.
Deliquescent - Melting and becoming a liquid by absorbing
moisture.
Desiccant - A material having a large proportion of
surface pores, capable of attracting and removing water vapor from the air.
Dew Point - The temperature at which moisture in the
air will begin to condense if the air is cooled at constant pressure. At this
point the relative humidity is 100%. The temperature to which air must be
cooled, at a given pressure and water-vapor content, for it to reach
saturation; the temperature at which dew begins to form.
Demand - Flow of air at specific conditions required
at a point or by the overall facility.
Diaphragm - A stationary element between the stages of
a multi-stage 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 cooling - A method of removing heat from the flowing
medium by circulation of a coolant in passages built into the diaphragm.
Diffuser - A stationary passage surrounding an
impeller, in which velocity pressure imparted to the flowing medium by the
impeller is converted into static pressure.
Digital Controls - See Logic Controls. https://www.cagi.org/
Discharge Pressure - Air pressure produced at a particular point
in the system under specific conditions.
Discharge Temperature - The temperature at the discharge flange of
the compressor.
Displacement - The volume swept out by the piston or
rotor(s) per unit of time, normally expressed in cubic feet per minute.
Droop - The drop in pressure at the outlet of a
pressure regulator, when a demand for air occurs.
Dynamic Type
Compressors - Compressors in
which air or gas is compressed by the mechanical action of rotating impellers
imparting velocity and pressure to a continuously flowing medium. (Can be
centrifugal or axial design)
Efficiency
- Any reference to
efficiency must be accompanied by a qualifying statement which identifies the
efficiency under consideration, as in the following definitions of efficiency:
Efficiency,
Compression - Ratio of
theoretical power to power actually imparted to the air or gas delivered by the
compressor.
Efficiency, Isothermal - Ratio of the theoretical work (as
calculated on an isothermal basis) to the actual work transferred to a gas
during compression.
Efficiency, Mechanical - Ratio of power imparted to the air or gas
to brake horsepower (bhp).
Efficiency, Polytropic - Ratio of the polytropic compression energy
transferred to the gas, to the actual energy transferred to the gas.
Efficiency, Volumetric - Ratio of actual capacity to piston
displacement.
Exhauster - A term sometimes applied to a compressor in
which the inlet pressure is less than atmospheric pressure.
Expanders - Turbines or engines in which a gas expands,
doing work, and undergoing a drop in temperature. Use of the term usually
implies that the drop in temperature is the principle objective. The orifice in
a refrigeration system also performs this function, but the expander performs
it more nearly isentropically, and thus is more effective in cryogenic systems.
Filters - Devices for separating and removing
particulate matter, moisture or entrained lubricant from air.
Flange connection - The means of connecting a compressor inlet
or discharge connection to piping by means of bolted rims (flanges).
Fluidics - The general subject of instruments and
controls dependent upon low rate of flow of air or gas at low pressure as the
operating medium. These usually have no moving parts.
Free Air - Air at atmospheric conditions at any
specified location, unaffected by the compressor.
Full-Load - Air compressor operation at full speed with
a fully open inlet and discharge delivering maximum air flow.
Gas - One of the three basic phases of matter.
While air is a gas, in pneumatics the term gas normally is applied to gases
other than air.
Gas bearings - Load carrying machine elements permitting
some degree of motion in which the lubricant is air or some other gas.
Gauge Pressure - The pressure determined by most instruments
and gauges, usually expressed in psig. Barometric pressure must be considered
to obtain true or absolute pressure.
Guide vane - A stationary element that may be adjustable
and which directs the flowing medium approaching the inlet of an impeller.
Head,
Adiabatic - The energy, in foot
pounds, required to compress adiabatically to deliver one pound of a given gas
from one pressure level to another.
Head, Polytropic - The energy, in foot pounds, required to
compress polytropic to deliver one pound of a given gas from one pressure level
to another. https://www.cagi.org/
Horsepower, Brake - Horsepower delivered to the output shaft of
a motor or engine, or the horsepower required at the compressor shaft to
perform work.
Horsepower, Indicated - The horsepower calculated from compressor
indicator diagrams. The term applies only to displacement type compressors.
Horsepower,
Theoretical or Ideal - The horsepower
required to isothermally compress the air or gas delivered by the compressor at
specified conditions.
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.
Humidity, Specific - The weight of water vapor in an air vapor
mixture per pound of dry air.
Hysteresis - The time lag in responding to a demand for
air from a pressure regulator.
Impeller
- The part of the rotating
element of a dynamic compressor which imparts energy to the flowing medium by
means of centrifugal force. It consists of a number of blades which rotate with
the shaft.
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 by a device
called an indicator.
Inducer - A curved inlet section of an impeller.
Inlet Pressure - The actual pressure at the inlet flange of
the compressor.
Intercooling - The removal of heat from air or gas between
compressor stages.
Intercooling, degree
of - The difference in
air or gas temperatures between the inlet of the compressor and the outlet of
the intercooler.
Intercooling, perfect - When the temperature of the air or gas
leaving the intercooler is equal to the temperature of the air or gas entering
the inlet of the compressor.
Isentropic compression - See Compression, https://www.cagi.org/
Isothermal compression - See Compression, https://www.cagi.org/
Liquid piston
compressor - A compressor in
which a vane rotor revolves in an elliptical stator, with the spaces between
the rotor and stator sealed by a ring of liquid rotating with the impeller.
Load Factor - Ratio of average compressor load to the
maximum rated compressor load over a given period of time.
Load Time - Time period from when a compressor loads
until it unloads.
Load/Unload Control - Control method that allows the compressor
to run at full-load or at no load while the driver remains at a constant speed.
Modulating
Control - System which adapts
to varying demand by throttling the compressor inlet proportionally to the
demand.
Multi-casing
compressor - Two or more compressors,
each with a separate casing, driven by a single driver, forming a single unit.
Multi-stage axial
compressor - A dynamic
compressor having two or more rows of rotating elements operating in series on
a single rotor and in a single casing.
Multi-stage
centrifugal compressor - A dynamic
compressor having two or more impellers operating in series in a single casing.
Multi-stage
compressors - Compressors having
two or more stages operating in series.
Perfect
Intercooling - The condition when
the temperature of air leaving the intercooler equals the air at the compressor
intake.
Performance curve - Usually a plot of discharge pressure versus
inlet capacity and shaft horsepower versus inlet capacity.
Piston Displacement - The volume swept by the piston; for
multistage compressors, the piston displacement of the first stage is the
overall piston displacement of the entire unit.
Pneumatic Tools - Tools that operate by air pressure.
Polytropic compression -. https://www.cagi.org/
Polytropic head - https://www.cagi.org/
Positive displacement
compressors - Compressors in
which successive volumes of air or gas are confined within a closed space and
the space mechanically reduced, resulting in compression. These may be reciprocating
or rotating.
Power, theoretical
(polytropic) - The mechanical
power required to compress polytropically and to deliver, through the specified
range of pressures, the gas delivered by the compressor.
Pressure- Force per unit area, measured in pounds per
square inch (psi).
Pressure, Absolute - The total pressure measured from absolute
zero (i.e. from an absolute vacuum).
Pressure, Critical – https://www.cagi.org/
Pressure Dew Point - For a given pressure, the temperature at
which water will begin to condense out of air.
Pressure, Discharge - The pressure at the discharge connection of
a compressor. (In the case of compressor packages, this should be at the
discharge connection of the package)
Pressure Drop - Loss of pressure in a compressed air system
or component due to friction or restriction.
Pressure, Intake - The absolute total pressure at the inlet
connection of a compressor.
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 rise - The difference between discharge pressure
and intake pressure.
Pressure, Static - The pressure measured in a flowing stream
in such a manner that the velocity of the stream has no effect on the
measurement.
Pressure, Total - The pressure that would be produced by
stopping a moving stream of liquid or gas. It is the pressure measured by an
impact tube.
Pressure, Velocity - The total pressure minus the static
pressure in an air or gas stream.
Rated Pressure - The operating pressure at which compressor
performance is measured.
Required Capacity - Cubic feet per minute (cfm) of air required
at the inlet to the distribution system.
Receiver - A vessel or tank used for storage of gas
under pressure. In a large compressed air system there may be primary and secondary
receivers.
Reciprocating
compressor - Compressor in which
the compressing element is a piston having a reciprocating motion in a
cylinder.
Relative Humidity - The ratio of the partial pressure of a
vapor to the vapor saturation pressure at the dry bulb temperature of a
mixture.
Rotor - The rotating element of a compressor. In a
dynamic compressor, it is composed of the impeller(s) and shaft, and may
include shaft sleeves and a thrust balancing device.
Sequence - The order in which compressors are brought
online.
Shaft - The part by which energy is transmitted
from the prime mover through the elements mounted on it, to the air or gas
being compressed.
Sole plate - A pad, usually metallic and embedded in
concrete, on which the compressor and driver are mounted.
Specific gravity - The ratio of the specific weight of air or
gas to that of dry air at the same pressure and temperature.
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.
Specific Weight - Weight of air or gas per unit volume.
Speed - The speed of a compressor refers to the
number of revolutions per minute (rpm) of the compressor drive shaft or rotor
shaft.
Stages - A series of steps in the compression of air
or a gas.
Standard Air - The Compressed Air & Gas Institute and
PNEUROP have adopted the definition used in ISO standards. This is air at 14.5
psia (1 bar); 68 F (20 C) and dry (0% relative humidity).
Start/Stop Control - A system in which air supply is matched to
demand by the starting and stopping of the unit.
Super compressibility - See Compressibility. https://www.cagi.org/
Surge - A phenomenon in centrifugal compressors
where a reduced flow rate results in a flow reversal and unstable operation.
Surge limit - The capacity in a dynamic compressor below
which operation becomes unstable.
Temperature,
Absolute - The temperature of
air or gas measured from absolute zero. It is the Fahrenheit temperature plus
459.6 and is known as the Rankine temperature. In the metric system, the
absolute temperature is the Centigrade temperature plus 273 and is known as the
Kelvin temperature.
Temperature, Critical - See Critical Temperature. https://www.cagi.org/
Temperature, Discharge - The total temperature at the discharge
connection of the compressor.
Temperature, Inlet - The total temperature at the inlet
connection of the compressor.
Temperature Rise Ratio - The ratio of the computed isentropic
temperature rise to the measured total temperature rise during compression. For
a perfect gas, this is equal to the ratio of the isentropic enthalpy rise to
the actual enthalpy rise.
Temperature, Static - The actual temperature of a moving gas
stream. It is the temperature indicated by a thermometer moving in the stream
and at the same velocity.
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.
Torque - A torsional moment or couple. This term
typically refers to the driving couple of a machine or motor.
Total Package Input
Power - The total
electrical power input to a compressor, including drive motor, belt losses,
cooling fan motors, VSD or other controls, etc.
Unit
type compressors - Compressors of 30
bhp or less, generally combined with all components required for operation.
Unload - (No load) Compressor operation in which no
air is delivered due to the intake being closed or modified not to allow inlet
air to be trapped.
Vacuum
pumps - Compressors which
operate with an intake pressure below atmospheric pressure and which discharge
to atmospheric pressure or slightly higher.
Valves - Devices with passages for directing flow
into alternate paths or to prevent flow.
Volute - A stationary, spiral shaped passage which
converts velocity head to pressure in a flowing stream of air or gas.
Water-cooled compressor - Compressors cooled by water circulated through jackets surrounding cylinders or casings and/or heat exchangers between and after stages. https://www.cagi.org/
piston and rotary screw service
www.hkaircompressors.com
214-428-2868
piston and rotary screw service
www.hkaircompressors.com
214-428-2868
piston and rotary screw service
www.hkaircompressors.com
214-428-2868
piston and rotary screw service
www.hkaircompressors.com
214-428-2868
piston and rotary screw service
www.hkaircompressors.com
214-428-2868
