Operating Characteristics of Positive Displacement Pumps Quiz

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Questions and Answers

What is the main principle of operation for positive displacement pumps?

Creating a void at the suction inlet, filling it with incompressible fluid, and then moving the fluid to the discharge (correct)
Filling the void with compressible fluid
Moving the fluid from the discharge to the suction inlet
Creating a void at the discharge inlet

What happens if a positive displacement pump is driven at a constant speed?

It supplies a variable volume of fluid based on the discharge head
It causes damage to the pump or piping system
It fails to develop any pressure
It supplies a constant volume of fluid regardless of the discharge head (correct)

Why must positive displacement pumps be equipped with a pressure relief device in the discharge line?

To prevent any fluid flow to the storage tank
To prevent damage to the pump or piping system if the discharge valve is inadvertently closed (correct)
To avoid developing considerable vacuum at the suction inlet
To increase the discharge pressure

What distinguishes positive displacement pumps from centrifugal pumps in terms of clearance between impeller and casing?

Positive displacement pumps have minute clearance compared to centrifugal pumps (A) Signup and view all the answers

Why do positive displacement pumps develop considerable discharge pressure?

Due to minute clearance between pressure-imposing element and pump housing (A) Signup and view all the answers

What is the reason positive displacement pumps are considered self-priming?

They can develop great vacuum and draw fluids to considerable height (C) Signup and view all the answers

Why is it advisable to manually prime rotary types of positive displacement pumps before starting?

They do not develop great suction lift like reciprocating pumps do (B) Signup and view all the answers

What should be checked prior to removing a lockout when starting positive displacement pumps?

Examine the coupling and ensure it is secure and does not have excessive play (C) Signup and view all the answers

What should be monitored after starting a pump according to the text?

Suction and discharge pressures, pump temperature, pump vibration, connections, and seals for leakage (A) Signup and view all the answers

What is a recommended routine check for all pumps according to the text?

Monitoring lubricator levels, adding oil when required, monitoring suction and discharge pressures, checking for leaks in mechanical seals or packing, tightening the packing if required, reporting maintenance concerns (D) Signup and view all the answers