Review questions

REVIEW QUESTIONS

On Compressors

1. What is compressor? Discuss the working principle of an air compressor.

[A.U., Nov/Dec 2007] 

[Ans. Refer Section 11.3] •

2. Explain the working principle of piston type compressor with neat sketch. 

[A.U., Nov/Dec 2006; Nov/Dec 2012] 

[Ans. Refer Section 11.3]

3. With a neat sketch, explain the working principle of a screw compressor.

 [A.U., May/June 2012] 

[Ans. Refer Section 11.4]

On Fluid Conditioners

4. Draw a neat sketch of pneumatic filter and explain its construction and working. Also give the graphical symbol.

[AU., May/June 2006; May/June 2009] 

[Ans. Refer Section 11.7] 

5. Describe the function of an air pressure regulator with neat sketch. (or) Using a neat sketch, explain the construction and working of a pneumatic regulator. Also give its graphical symbol. 

[A.U., Apr/May 2005; Apr/May 2008; Apr/May 2010] 

[Ans. Refer Section 11.8]

6. Describe the function, construction and operation of an "FRL” trio unit. (or) With neat sketch, explain the importance of a filter and regulator unit in a pneumatic system. 

[A.U., Noy/Dec 2006; Nov/Dec 2007; Nov/Dec 2011; Nov/Dec 2013; Apr/May 2017; Apr/May 2018] 

[Ans. Refer Section 11.10]

7. Write the procedures for selection of filter, regulator and lubricator.

[A.U., May/June 2013] 

[Ans. Refer Section 11.10.1] 

8. Write a short note on mufflers.

 [A.U., May/June 2013] 

[Ans. Refer Section 11.11]

PROBLEMS FOR PRACTICE

1. Air is used at a rate of 1 m3/min from a receiver 50°C and 10 bar gauge. If the atmospheric air-is 1 bar and the atmospheric temperature is 20°C, how many standard m3/min of free air must the compressor provide? 

[Ans. 9.071 m3/min]

2. (i) Calculate the required size of a receiver that must supply air to a pneumatic system consuming 1.2 standard m3/min for 10 min between 12 bar and 8 bar before the compressor resumes operation.

(ii) What size is required if the compressor is running and delivering air at 0.35  standard m3/min ?

[Ans. (i) 3.03 m3 ; (ii) 2.14 m3]

3. Determine the output pressure of a compressor operating with the following data: 

Overall efficiency of compressor = 74%

Actual power required to drive the compressor = 15 kW

Compressor inlet pressure = Atmospheric

Compressor outlet flow rate = 4.25 standard m3/min.

2. Using equation 11.3, find the unknown outlet pressure (Pout)].

[Ans. 804.6 kPa absolute or 704.6 kPa gauge]