Question

Question 1 (a) Explain how compressed air quality is classified. (b) What is the importance of removing atmospheric moisture from compressed air? (c) Describe how the following systems dry compressed air 121 (i Aftercooling i Refrigeration drying (ii) Adsorption drying 12] 121 121

Answer 1

(a) Maintaining air quality is so important that the International Standards Organisation (ISO) developed six compressed air quality classes, as defined by ISO 8573.1.Class 0 is the compressed air with highest quality.The six compressed air quality classes are shown below:-

(b) Moisture in compressed air causes problems in the operation of air motors, pneumatic systems, and solenoid valves.Moisture contamination has the following effects:-

1.Rust and corrosion in the air system piping

2.Inadequate air tool lubrication

3.Damage to labelling, packaging and the finished goods

4.Productivity losses throughout your operation.

Hence, to overcome all these effects, it is very important to remove atmospheric moisture from the compressed air.

(c) (i) Aftercooling-Aftercoolers decreases the amount of water vapor in a compressed air system by condensing the water vapor into liquid form. Aftercoolers combined with a seperator are an excellent way to reduce moisture in a compressed air system.

(ii) Refrigeration Drying :- A refrigerated compressed air dryer is a type of compressed air dryer, used to dry compressed air. Compressed air always contains water, coming from the air that is sucked in by the compressor.Refrigerated compressed air dryers are one of the most common used types of air dryers .All water vapor that was in the air condenses into water.The liquid water is then removed from the compressed air by a water-trap.

(iii)  Adsorption drying :- Drying compressed air through adsorption represents a purely physical process in which water vapor( known as adsorbate ) is bound to the drying medium (known as adsorbent) through the force of molecular adhesion. Adsorbents are solids in spherical and granular form which are permeated by an array of pores. The water vapor is deposited onto the internal and external surface of the adsorption medium.

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