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Centrifugal Pump Priming and Starting Quiz

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Questions and Answers

What does priming a centrifugal pump involve?

Replacing the wearing rings, mechanical seals, and packing
Adjusting the discharge valve
Filling the pump casing and suction line with the liquid being pumped (correct)
Cleaning the impeller of the pump

Why is it important to prime a centrifugal pump before starting?

To reduce the wear on the pump casing
To increase the flow rate of the pump
To prevent the impeller from churning air instead of producing suction (correct)
To maintain the pressure in the discharge valve

What is the purpose of the foot valve in the pump suction line?

To allow water to enter the suction line and prevent it from flowing back out (correct)
To reduce the noise produced by the pump
To increase the temperature of the water
To control the speed of the pump

What should be done to prime a centrifugal pump when it is located below the source of supply?

Close the discharge valve, open the suction valve, and then open the air vent valves to allow air in the pump casing to escape (B) Signup and view all the answers

What happens if a centrifugal pump is not primed before starting?

The impeller will churn air instead of producing suction (D) Signup and view all the answers

What is the role of external supply valve when priming a centrifugal pump from an external source?

To provide priming water for the pump (D) Signup and view all the answers

Why are air vent valves opened when priming a centrifugal pump?

To allow the air in the pump casing to escape (D) Signup and view all the answers

What type of check valve is used in the pump suction line?

Flap type check valve (C) Signup and view all the answers

What happens when water flows from the air vent valves during priming?

The air vent valves can be closed (D) Signup and view all the answers

What happens if a centrifugal pump runs dry even for relatively short periods of time?

Serious damage occurs to pumps (C) Signup and view all the answers

What is the purpose of the foot valve in the suction line?

To prevent water from escaping the suction line (B) Signup and view all the answers

What is the recommended action if the suction pressure gauge indicates the strainer is plugging when starting the pump for the first time?

Stop the pump, remove the screens, clean, and re-install them (A) Signup and view all the answers

Why should the alignment of the pump and its driver be rechecked after they have run for a short time?

To confirm that the motor and pump have not shifted due to temperature changes (D) Signup and view all the answers

What is the purpose of checking the driver and pump rotation before starting the pump?

To check if the pump shaft turns in the correct direction (A) Signup and view all the answers

Why must a separate hand-operated positive displacement priming pump be used in some cases?

To avoid air entrapment in the pump casing (C) Signup and view all the answers

What is a common reason for troubles developing in new plants after a short period of operation?

Improper installation of the connecting piping (B) Signup and view all the answers

Why should bearings be carefully inspected, cleaned, and lubricated before starting any pump?

To avoid overheating and vibration of the pump bearings (D) Signup and view all the answers

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