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Learning Objective: Understand the air compressor and reservoirs types, construction and operation on board.

Specific Learning Objectives: Explain the uses of compressed air onboard. State the compressor types that may be found

onboard. Explain the operation of single and multi-stage air

compressor Sketch and describe the inter and after cooling. Describe the air compressor components assembly

and materials. With the aid of diagram, explain the air reservoir

construction. Describe the safety features an air compressor. Describe the design features of air reservoir. Describe the safety features of air reservoir.

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Dynamic Air Compressor

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Dynamic Air Compressor

Increasing the pressure of gases by imparting to it the kinetic energy, which is converted into pressure energy into a diffuser. Means that air is forced into space and energy is added to it by increasing the velocity. Velocity will decrease by volute casing or diffuser. Thus loss of velocity will cause the pressure to increaseat the discharge side of the compressor.

This type of compressor is considered under continuous mode in which the gas moved into the compressor is moved through the compressor and discharged without interruption of the flow at any point in the process

These are multi-blade compressors and are further subdivided into:

Centrifugal compressor

Jet compressor

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Centrifugal Air Compressor

A high peripheral velocity is imparted to the gases being compressed by the blades of the impeller which rotates at a speed of 3000 to 27000 rpm to produce high-pressure discharge or by converting angular momentum imparted by the rotatingimpeller (dynamic displacement)

The centrifugal force developed in this way partially compresses the gases. Further compression occurs in diffuser (reduced velocity which is depending upon the direction of gases flow) at outlet from impeller. Compressor can be radial or axial.

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Centrifugal compressors are now most frequently used for medium volume and medium pressure air delivery. One advantage of a centrifugal compressor is the smooth discharge of the compressed air.

Simplified centrifugal

compressor

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The centrifugal force utilized by the centrifugal compressor is the same force utilized by the centrifugal pump. The air particles enter the eye of the impeller then is thrown against the casing

The air becomes compressed as more and more air is thrown out to the casing by the impeller blades

The air is pushed along the volute casing cause pressure of the air is increased that

The impeller blades curve forward, which is opposite to the backward curve used in typical centrifugal liquid pumps or considered can use a variety of blade orientation including both forward and backward curves.

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There may be several stages to a centrifugal air compressor, as in the centrifugal pump, and the result would be the same; a higher pressure would be produced.

The air compressor is used to create compressed or high pressure air for a variety of uses. Some of its uses are pneumatic control devices, pneumatic sensors, pneumatic valve operators, pneumatic motors, and starting air for diesel engines.

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Internal view of a multistage

centrifugal compressor

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Jet Compressor

In jet compressor the driving vapour attains a high supersonic velocity in a Laval nozzle and then mixed with the gases to be compressed in a mixing chamber and leading it at high velocity to the diffuser where kinetic energy is converted into pressure energy

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GAS-JET COMPRESSOR

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Summary

Uses of Compressed Air onboard.

Compressor Types

Operation of Single and Multi-stage Air Compressor

Components of Air Compressor

Safety features an Air Compressor and Air Reservoir.

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Thank You

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