air compressor basics by alex persyn...engine power rating x y z air compression page 13 engines are...

Doosan InfracoreConstruction Equipment

May 2010

Air Compressor Basicsby Alex Persyn

Air under ambient conditions is taken in to the compressor then energised by reducing the volume which in turn increases the pressure

The usable stored energy within the air is utilised when the air is released back to its original state.

Air Compression

Air Compression

Let’s look at the molecule in the left container……...

……..now let’s move the piston down….

……the molecule now hits the piston more times…...

THE PRESSURE HAS INCREASED

Air Compression

There are two basic ways to push air molecules:

Reciprocating Movement

– Piston and Cylinder

Rotary Movement

– Fan Blades

– Centrifugal Rotors

– Screws

Air Compression

The rated capacity of a positive displacement compressor is usually given as.

m³/min - cubic metres/minute (=35.31 cfm)

Cfm - cubic feet / minute

l/s - litres per second

Air Compression

psi - pounds per square inch

A 100 psi unit is usually referred to as 7 barA 175 psi unit is usually referred to as 12 barA 300 psi unit is usually referred to as 21 bar

The operating discharge pressure for portable air compressors is usually given as.

bar - 1 bar (= 14.5 psi)

Air Compression

• The work required to compress a given amount of air (cubic metre ) in a specific amount of time (minute) to a specified pressure (Bar) is measured in kilowatts.

• For a given amount of work (kilowatt ) you can attain many different compressor ratings.

Bar m³/min 7.0 10.0 8.6 9.2

10.3 8.5

• Example, with a 75 kW engine here are a few of the possible compressed air combinations:

Air Compression

Compressor Power

Airflow (CFM)

Pow

er (

BH

P)

Engine Power Rating

X Y Z

Air Compression

Engines are rated to produce a certain amount of power at a specific speed (rpm).

As you reduce the speed you (generally) reduce the power output of the engine.

Since rotor speed is dependent on engine speed…...

…air flow relates to engine speed !

Air Compression

A mobile source of independent power which is:

- Safe in use

- Flexible in application.

- Cannot be damaged by overload

Portable Compressor

Main components:

• Engine

• Air End (compressor)

• Air Oil Separator

• Coolers (Engine and Compressor)

• Undercarriage

Portable Compressor

The mechanical power of the Engine turns the airend, through which is fed a combination of oil and air in order to create compressed air. The compressed air is separated and filtered through the separator, the cleaner compressed air is then distributed via the ‘service valves’.

Portable Compressor

Moving away from Ingersoll-Rand branded engines

Portable Compressor

Airend expected life time: 15.000 hrs

Portable Compressor

Portable Compressor

SEPARATOR TANK

Maintains a min. pressure (~5bar) in the receiver to:keep the oil flowing.limit pressure drop across the separator.

Continuous operation at min pressure results in oil carry over due to insufficient scavenge flow.

MINIMUM PRESSURE VALVE

LUBRICATION & COOLING

Cool box design with pusher type fan.

COOLING FAN

The fan is a pusher type, fresh air flows around the engine.

Make sure the compressor doors are closed during operation to prevent overheating!

The oil cooler and radiator are two separate units mounted on top of each other

Coolers (Engine and Compressor)

Portable Compressor

LUBRICATION & COOLING (7/71 – 12/56)

COOLER PACKAGE

Aftercooler Radiator Oil Cooler

Check every day and clean if necessary to ensure high efficiency.

Portable Compressor

air compressor basics by alex persyn...engine power rating x y z air compression page 13 engines are...

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