Consider the following statements regarding Pumping Systems in buildings:1.Net Positive Suction Head (NPSH) is a critical parameter to prevent cavitation in pumps.2.Priming is necessary for centrifugal pumps if the pump is located above the liquid level (suction lift).3.A booster pump is used to maintain constant pressure in high-rise water distribution systemsWhich of the statements given above is/are correct?

Correct Answer: D - 1, 2 and 3

Quick Concept Explanation

Centrifugal pumps require sufficient pressure at the suction to avoid local vaporization and cavitation; this is evaluated using NPSH. When a pump is above the liquid level, the casing/suction line must be primed because a centrifugal pump cannot normally evacuate air and establish suction by itself.

Exam focus: Cavitation questions: compare available and required NPSH. Common trap: Priming is unnecessary only for self-priming arrangements or when suction is already flooded.

Statement-wise Verification

• Statement 1 - Correct.
  Net Positive Suction Head (NPSH) is a critical parameter to prevent cavitation in pumps.
  Centrifugal pumps require sufficient pressure at the suction to avoid local vaporization and cavitation; this is evaluated using NPSH.
• Statement 2 - Correct.
  Priming is necessary for centrifugal pumps if the pump is located above the liquid level (suction lift).
  When a pump is above the liquid level, the casing/suction line must be primed because a centrifugal pump cannot normally evacuate air and establish suction by itself.
• Statement 3 - Correct.
  A booster pump is used to maintain constant pressure in high-rise water distribution systems
  Booster pumps are used to maintain required pressure in tall-building distribution zones.

Core Concept

Centrifugal pumps require sufficient pressure at the suction to avoid local vaporization and cavitation; this is evaluated using NPSH. When a pump is above the liquid level, the casing/suction line must be primed because a centrifugal pump cannot normally evacuate air and establish suction by itself. Booster pumps are used to maintain required pressure in tall-building distribution zones.

Formula / Key Relationship

Require NPSH_available > NPSH_required with design margin.

Why the Other Options Are Wrong

Option A is incorrect because it omits correct statement(s) 3. Option B is incorrect because it omits correct statement(s) 1. Option C is incorrect because it omits correct statement(s) 2.

Exam Shortcut / Approach

Cavitation questions: compare available and required NPSH.

Common Mistake

Priming is unnecessary only for self-priming arrangements or when suction is already flooded.

Quick Revision

NPSH Priming and Booster Pumps is linked with Pump Operation, Pumping Systems and Electrical Building Services. Cavitation questions: compare available and required NPSH.