Centrifugal pump installation – essential practices and precautions Which of the following statements together describe standard good practice for starting and operating a centrifugal pump in a water-supply installation?

Introduction / Context:
Centrifugal pumps are the workhorses of municipal water systems. Safe and efficient operation depends on correct priming, sensible piping practice, and appropriate starting procedures that avoid overloading and loss of prime.

Given Data / Assumptions:

• A standard end-suction centrifugal pump serving a water-supply line.
• Conventional suction foot valve (or a check at the wet well) used to retain water in the suction line.
• Operators can start the pump with the discharge valve throttled as needed to limit load.

Concept / Approach:
Before start, the casing and suction must contain water to prevent dry running and to allow the impeller to generate head—hence priming is mandatory. A foot valve (non-return valve) prevents backflow and loss of prime when the pump stops. Piping at the pump nozzles is often the same as or slightly smaller than the downstream distribution main; the overall delivery main is frequently larger to reduce velocity and friction losses. Starting against a wide-open discharge on an empty line can produce high flow at low head, increasing power draw and risking motor overload; throttling the discharge at start-up is standard practice.

Step-by-Step Solution:
Confirm (a): Priming is essential to avoid air binding and damage.Confirm (c): The foot valve retains water in the suction line, maintaining prime.Interpret (b): While site-specific, the delivery main is commonly larger than the pump nozzles to limit friction; the statement captures that relation.Evaluate (d): Starting with open discharge and an empty line can cause excessive flow and motor overloading; throttling is safer.Therefore, the comprehensive correct choice is “All the above.”

Verification / Alternative check:
Commissioning manuals recommend priming, check/foot valves for priming retention, and starting with a throttled discharge to control load and avoid water hammer.

Why Other Options Are Wrong:

• Choosing any single statement ignores interdependent best practices.

Common Pitfalls:
Dry starting, suction leaks that admit air, and starting with fully open discharge on an empty, short line—all of which can damage the pump or trip the motor.

Final Answer:
All the above