Question

An air vessel in the delivery side of a reciprocating pump:
1. maintains steady discharge output
2. prevents cavitation in the system.
3. enables suction head to be increased
4. enable the pump to run at higher speed

Answer 1

Correct Answer - Option 1 : maintains steady discharge output

Explanation:

Air vessel:

• It is a closed chamber fitted on the suction as well as delivery side, near the pump cylinder to reduce the accelerating head.
• To reduce the acceleration head we need to reduce the length of the suction pipe and the length of the delivery pipe in which fluctuation of velocity occurs.
• This is done by fitting air vessels as close as possible.
• Thus between air vessel and cylinder only fluctuating velocity will occur. Below air vessel on the suction side and above air vessel on delivery side velocity will be constant.

 

Functions of air vessel:

1) On the suction side:

• Reduction of the possibility of separation of flow
• The pump can run at a higher speed.
• The length of the suction pipe below the air vessel can be increased.

2) On the delivery side:

• A constant rate of discharge can be ensured.
• Save power required to drive the pump (For single-acting pump, percentage work saved is 84.8% and for double-acting pumps the percent work save is 39.2%)