Two marks questions and answers

TWO MARKS QUESTIONS AND ANSWERS

On Compressors

1. What is the use of a compressor in a pneumatic system ?

In pneumatic systems, compressors are used to compress and supply the required quantities of air.

2. How are air compressors classified?

3. What are the types of compressors which are used in the fluid power system?

Piston type, screw type and vane type compressors are used in the fluid power system. 

4. What does staging mean ?

Staging means dividing the total pressure among two or more cylinders by allowing the outlet from one cylinder into the inlet of the next cylinder and so on.

5. What is multi-stage compressor?

When the compression of air from the initial pressure to the final pressure is carried out in more than one cylinder, then the compressor is known as multi-stage compressor.

6. Why are multi-stage compressors preferred over single-stage compressors ?

When the multistage compressors are used, the effective cooling can be implemented between stages. This effective cooling (i) reduces input power requirements, and (ii) increases the efficiency of the compressor.

7. What is the purpose of compressor starting unloader control?

The 'starting unloader control' is used to start the compressor whenever desired. This arrangement releases the pressure in the piping to the atmosphere so that the compressor can be started whenever needed.

8. How can you specify an air compressor? (or) How can you rate a compressor? 

Air compressors are generally specified by the following :

(i) Outlet pressure of air that can be delivered by the compressor,

(ii) Capacity of volume of air that can be delivered by the compressor, and

(iii) Compressor configuration and cylinder geometry.

On Fluid Conditioners

9. What is the purpose of fluid conditioners ?

The purpose of fluid conditioners is to make the compressed air more acceptable and suitable fluid medium for the pneumatic system components as well as for operating personnel.

10. Name any four fluid conditioners used in pneumatic systems.

1. Filters,

2. Regulators,

3. Lubricators, and

4. Mufflers.

11. What is the function of air filters ?

The function of air filters is to remove all foreign matter and allow dry, clean air to flow without restriction to the regulator and then on to the lubricator.

12. Name the various types of filters used in the pneumatic system. 

1. Dry filters (with replaceable cartridges), and

2. Wet filters (where the incoming air is bubbled through an oil bath then passed through a wire mesh filter).

13. What is the purpose/function of an air pressure regulator ?

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.

14. Sketch the graphical symbol of pneumatic regulator (or air pressure regulator).

15. What is the need of lubricator unit in the pneumatic system?

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.

16. What do you mean by FRL unit?

The combination of filter, regulator, and lubricator is often labelled as FRL unit or service unit.

17. Why are mufflers used in pneumatic systems?

The function of mufflers is to control the noise caused by a rapidly exhausting air-stream flowing into the atmosphere.

18. What is the need for air dryers ?

The air dryers are needed to remove all water vapour/moisture from the air leaving the compressor.

19. Draw the graphic symbol of a FRL unit.

20. Draw the graphic symbol of (a) air compressor, (b) filter, and (c) muffler.