Reciprocating pump with air vessel — percentage saving of work By fitting an air vessel to a reciprocating pump, work and power savings occur due to flow smoothing. What is the typical percentage saving for a double-acting reciprocating pump?

Introduction:
Air vessels are used on suction and delivery lines of reciprocating pumps to reduce acceleration head, smoothen discharge, and lower the fluctuating power requirement. The percentage saving differs between single-acting and double-acting pumps because the flow pulsation patterns differ.

Given Data / Assumptions:

• Double-acting reciprocating pump.
• Idealized analysis of acceleration head reduction with properly sized air vessels.

Concept / Approach:
The principal benefit is the reduction of periodic acceleration and deceleration of the fluid column. This reduces pressure fluctuations and the corresponding work over a cycle. Standard results show that for single-acting pumps the saving is higher, whereas for double-acting pumps it is approximately half that magnitude due to inherently smoother flow.

Step-by-Step Solution:

Verification / Alternative check:
These percentages appear consistently in standard fluid machinery texts. Practical installations show significant reduction in pressure pulsations and motor size for the same duty.

Why Other Options Are Wrong:

• 39.2% / 24.4%: lower than the accepted value for double-acting arrangements.
• 84.8% / 88.4%: align more with single-acting results or exceed typical theoretical values.

Common Pitfalls:
Mixing up single- and double-acting savings; assuming air vessels eliminate all fluctuations (they reduce, not remove, pulsations).

Final Answer: