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COMPRESSORS

Group Members:

M. Fahad PP-038Taha Hassan PP-049

Ayesha Shoaib PP-032

Rimsha Khan PP-037

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WHAT IS A COMPRESSOR?

Compressors are mechanical devices that compressgases.

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WHY THE NEED?

Compressors have many everyday uses such as:

• Air conditioners (in cars, homes)

•

Home and industrial refrigeration• Hydraulic compressors for industrial machines

• Air compressors for industrial manufacturing

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CLASSIFICATION OF

COMPRESSORS

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POSITIVE DISPLACEMENT

COMPRESSORS  In this type the volume of the cylinder is reduced

mechanically to compress gas.

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DYNAMIC COMPRESSORS

  In this type the centrifugal force or the velocity ofmoving gas is used for the compression of gas.

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SINGLE-ACTING

COMPRESSORS  It is a compressor that has one discharge per

revolution of crankshaft.

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DOUBLE-ACTING

COMPRESSORS  It is a compressor that completes two discharge

strokes per unit of crankshaft. ost of the heavyduty compressors are dou!le acting.

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ROTARY SCREW

COMPRESSORS"otary screw compressors name given!ecause of two counter#rotating screws.

 $here are two types of rotary compressors:

• %il#in&ected

•%il#free

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MECHANISM'. %utside air rst travels through a

lter.

. Air goes through an inlet valve andinto the space !etween theinterlocking screws.

*. $he air moves along and travels tothe other end of the compressioncham!er.

+. $he area in which the air is

contained gets increasingly smaller.. In %il#In&ected, mi-ture ows into a

separator tank where the two areseparated.

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PROBLEMSPROBLEM # 1 

Compressor shuts down on high#temperature

POSSIBLE CAUSES: 

•  $oo low oil level

• /rong type of oil

•  $hermostatic valve not working

POSSIBLE SOLUTIONS: 

• ake up the oil level.

• 1se the appropriate type of oil

• "eplace2"epair the thermostatic valve

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PROBLEM # 2 

Compressor does not !uild up pressure

POSSIBLE CAUSES :

• Air leaks in shop

• Inlet valve malfunction

• Air demand e-ceeds compressor output

POSSIBLE SOLUTIONS: 

•

3ind and - shop air leaks• Check inlet valve for proper function

• Check air usage re4uirements on machinery

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CENTRIFUGAL COMPRESSORS

In centrifugal compressors continuous conversionof kinetic energy into pressure energy takes place.

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MECHANISM

'. 5ow pressure gas entersthe compressor.

. 6ains kinetic energy andpressure in impeller.

*. 7inetic energy isconverted in pressure

energy in the di8user.

+. 6as leaves the compressorat a higher pressure.

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SURGING

A momentary !ack#ow through the compressorfrom the discharge side to the suction side.

%ccurs when mass ow of gas falls !elow acritical level.

9urging causes:•

 i;culty in maintaining the speed.• $emperature rise within the compressor.• <oise in the compressor.

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ANTI SURGE SYSTEM

COMPRESSOR

ANTI SURGECONTROLLER

COOLER

ANTI SURGE  VALVE

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A reciprocating compressor or pistoncompressor is a positive#displacementcompressor that uses pistons driven !y a

crankshaft to deliver gases at high pressure.

RECIPROCATING

COMPRESSORS

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MECHANISM

'. $his type of compressoruses piston#cylinder tocompress the air.

. =iston moves !ack andforth to compress the air.

*. Compressor takes insidesuccessive amount of airand conne it in a closed

surface.+. =iston moves upward and

compresses the air anddisplaces it through

e-haust valve.

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PROBLEM # 1 Compressor pump knocking

POSSIBLE CAUSES: •  5oose motor pulley or y wheel•  5ow oil level in pump•  Car!on !uild up on valve or piston

POSSIBLE SOLUTIONS: •  Inspect2 $ighten pulley > ywheel•  Check compressor pump oil level•  Inspect valves > pistons for car!on !uild up 

COMMON PROBLEMS

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PROBLEM # 2 5ow discharge pressure

POSSIBLE CAUSES: •  Air leakage in lines•  5eaking valves•  /orn cylinder or piston rings

POSSIBLE SOLUTION S:

•  $ighten or replace leaking ttings•  Inspect air lines or pipes in shop

•  Inspect2 "eplace piston rings

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PROBLEM # 3 ?-cessive oil discharge in air

POSSIBLE CAUSES:

•  %il level in pump too high•  ?-cessive duty cycle of pump•

  /orn cylinder or piston rings

POSSIBLE SOLUTIONS:

•  "educe oil level•  "educe compressor duty cycle•  "eplace piston rings

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THANK YOU!