Hydraulic Machines MCQ with answer and solution

Concept

Air Vessels in Reciprocating Pumps

Formula

N/A

Step-by-step solution

1. Analyze Statement 1: Air vessels fit on reciprocating pumps to ensure a continuous, uniform supply (Correct). 2. Analyze Statement 2: Air vessels maintain smooth flow, preventing separation and cavitation (Correct). 3. Analyze Statement 3: Air vessels reduce friction losses rather than increasing them (Incorrect). 4. Select Option A (1 and 2 only).

Explanation

Option A (1 and 2 only) is correct because air vessels store compressed air to ensure a continuous and uniform supply of liquid and help prevent flow separation and cavitation in the pipes. Statement 3 is incorrect because air vessels actually reduce frictional head loss and saving energy, rather than increasing it.

Shortcut

To remember the key functions of Air Vessels in Reciprocating Pumps, use the phrase "Air Vessel = Smooth, Safe, Saving": - Smooth: Ensures a continuous and uniform supply/discharge rate. - Safe: Prevents flow separation and cavitation in suction and delivery pipes. - Saving: Reduces frictional head loss and saves power (it DECREASES friction, not increases).

Common mistake

A common mistake is selecting option D by assuming that air vessels increase frictional head loss because they add fitting resistance. In reality, air vessels smooth out flow fluctuations and reduce fluid acceleration, which significantly decreases friction power loss and head loss in the long pipeline. Another frequent error is confusing the function of air vessels in preventing separation with increasing work done.