2. 1. Filter:
i) To prevent entrance of solid contaminants to the system.
ii)To condensate and remove the water vapour that is present in the
air.
iii) To arrest submicron particles that may pose a problem in the
system components.
2. Regulator:
To regulate the incoming pressure to the system so that the desired air
pressure is capable of flowing at a steady condition.
3. Lubricator:
To provide lubrication for mating components of valves, cylinders etc.by
forming a mist of oil and air.
3. Factors Affecting Selection of Filters
While selecting the filters, the following factors at least should be taken into account:
1. Size of particles to be filtered from the system.
2. The capacity of the filter.
3. Accessibility and maintainability.
4. Life of the Filter.
4.
5. Working of Filter :
The air to be filtered is allowed downward with a swirling motion that forces the moisture and
the heavier particles to fall down. The deflector used in the filter mechanically separates the
contaminants before they pass through the cartridge filter. The filter cartridge provides a random
zig-zag passage for the airflow.
This type of airflow arrests the solid particles in the cartridge passage.
The water vapour gets condensed inside the filter and is collected at the bottom of the filter
bowl. Also, heavier foreign particles that are separated from the air are collected at the bottom
of the bowl. Then the accumulated water and other solid particles at the bottom of the filter
bowl are drained off with the use of an on-off drain valve located at the bottom of the filter
bowl.
6. AIR PRESSURE REGULATOR
Function:
The function of the air pressure regulator is to regulate the pressure of the incoming compressed air so as to
achieve the desired air pressure at a steady condition.
Types: The two types of air pressure regulators are :
1. Diaphragm-type regulator, and
2. Piston-type regulator.
7.
8. Working of air Pressure Regulator :
The diaphragm allows the proper amount of movement for opening and closing at the valve seat.
When the adjusting screw is in the fully retracted position, the valve is closed.
When the adjusting screw is turned to compress the adjusting and dampening springs, the valve is
opened. Thus the air is allowed from the inlet port to the outlet port. The pressure of the outlet air
depends upon the size of the valve opening that is maintained. This is determined by the compression
of the adjustable spring. Higher the spring compression, more will be the amount of opening and
hence more the pressure and vice versa.
The vent-holes are provided to let out the undesirable excessive outlet pressure, if any, into the
atmosphere. The dampening spring is provided to act as a dampening device needed to stabilize the
pressure.
9. AIR LUBRICATOR
Function : The function of an air lubricator is to add a controlled amount of oil with air to ensure
proper lubrication of internal moving parts of pneumatic components.
What is the best type of Lubricant for a Pneumatic System?
1. Generally a good-quality, light-grade spindle oil is used in pneumatic systems.
2. Sometimes, a mixture of 50% kerosene and 50% SAE 30 oil is also used as a lubricant.
10.
11. Construction and Operation Of Air Lubricator :
The construction and operation of a typical force-feed type air lubricator are illustrated in Fig.
Its operation is similar to the principle of simple carburetor used in the petrol engines to
obtain an air-fuel mixture.
As the air to be lubricated enters into the inlet pipe, the venturi ring located in the pipe
increases its velocity of low. It causes a local reduction in the upper chamber. This pressure
differential between upper and lower chambers causes suction of lubrication oil from the
oil reservoir to the upper chamber. Now the oil in the form of mist is sprayed in the air stream
and the air-oil mixture is obtained.
This air-oil mixture is forced to swirl as it leaves the central cylinder causing more oil
particles to be spread out of the air stream. The amount of oil dropping into the upper
chamber can be controlled by a needle valve.
