Mechanical Engineering - Hydraulic Machines - Discussion

In a reciprocating compressor, the air vessel is used to reduce the acceleration head.

1. Uniform flow
2. Accelereation reduce.
3. Friction heads reduce.

Ref: RS Khurmi

D is correct.

Acceleration means change in velocity.
We required uniform head.
That's why air vessel is used.

Air vessel in reciprocating pump are used to;

1. Continuous flow at a uniform rate.
2. Achieve higher speed.
3. Increase delivery head.
4. Reduce acceleration head.

Yes, A is also the correct answer but option D is the more important use of air vessel and hence correct answer for the question.

The reason is, air vessel are placed so that there is uniform flow in suction and delivery side which decreases the inertial force required to pump the fluid and hence saves power and gives better efficiency overall. And uniform discharge is also a desired effect, but not as important as reduction of power, or avoiding cavitation on the suction side.

Yes, the answer is d, I have read in a standard textbook, but I need explanation. So please explain the answer.

Mainly it is reduce fluctuating flow.

@Sushil.

Your doubt is obvious but you have not read this topic in much deep. The same question was asked in IES 2013. Paper 1. And also in Fluid Mechanics book of D. S. Kumar. So definitely D Is the Correct answer.

Option (a) should be correct because implementation of air vessel ensure continuous supply of fluid.