basic pneumatic system

BASIC PNEUMATIC SYSTEM

BASIC PNEUMATIC SYSTEM

AIR SOURCE

1. COMPRESSOR

Reciprocating Compressor

a. Single stage piston compressor

b. Double stage piston compressor

Single stage piston comressor

Recipricating compressor can be defined as those air compressor in which sucsessive volume of air enclosed and then elevated to a higher pressure by reducing the volume of the enclosure holding the air.

Air taken in atmospheric pressure is compressed to the required pressure in a single stroke.

Downward movement of the piston increases volume to create a lower pressure than that atmosphere, cousing air to enter the cylinder through the inlet valve.

At the end of the stroke, the piston moves upward, the inlet valve closes as the air is compressed, forcing the outlet valve open to discharge air into receiver tank.

Two stage piston compressor

In a single-stage compressor, when air is compressed above 6 bar, the excessive heat created greatly reduces the efficiency. Because of this, piston compressor used in industrial compressed air system are usually two stage.

Air taken in at atmospheric pressure is compressed in two stages to the final pressure.

If the final pressure is 7 bar, the first stage normally compresses the air to approximatelly 3 bar, after which it is cooled. It is then fed into second stage cylinder which compresses in to 7 bar.

The compressed air enters the second stage cylinder at greatly reduced temperature after passing through the inter-cooler, so improving the efficiency compared to a single stage unit. The final delivery temperature , may bein the region of 120 C

Rotary compressor

It has an eccentrically mounted rotor having a series of vane sliding in radial slots

As the rotor rotates, cetrifugal forces holds the vanes is contact with the stator wall and the space between tha adjacent blades decreases from air inlet to outlet, so compressing the air. Lubracating and sealing is achieved by injecting oil into the air stream near the inlet. The oil also acts as a coolant to remove some of the heat generated by compression, to limit the delivery tempreture to around 190( C

AFTER COOLER

A. Air- cooler

Air cooled type Aftercooler is an air to air heat exchanger.It use ambient air to cool the compressed air. The outlet temperature of the cooled compressed air should be approximately 15 C above the ambient air temperature

B. Water cooled

Water cooled type after cooler is an air to water heat exchanger. Its uses water to cool the compressed air. The temperature of the cooled compressed air should be approximately 10 C above the temperature of the cooling water.

Essentially, a steel shell housing tubes with water circulation on one side and air on the other side, usually arranged so that the flow is in oppositendirection through the cooler.

An automatic drain attached to, or integral with, tha aftercooler, removes tha accumulated condensation.

Aafter coolers should be equipped with a safety valve, pressure gauge, and it is recommended that thermometer pocket for air and water are included.

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basic pneumatic system

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