Pumping Systems and Hydraulics Flashcards

What is the term for the total head a pump must work against, including static head plus friction losses?

Answer: Total Dynamic Head

Total Dynamic Head (TDH) is the total equivalent head the pump must overcome, including static head, friction losses, and minor losses.

Cavitation in a centrifugal pump is most directly caused by which condition?

Answer: Insufficient Net Positive Suction Head Available (NPSHa)

Cavitation occurs when the available NPSH falls below the required NPSH, causing the liquid to vaporize at the impeller inlet.

On a pump curve, the point where the pump curve intersects the system curve is called the:

Answer: Operating Point

The operating point (or duty point) is where the pump curve crosses the system curve, defining the actual flow and head the pump will deliver.

A centrifugal pump running at twice its original speed will produce approximately how many times its original flow rate?

Answer: 2 times

By the affinity laws, flow rate varies directly with pump speed, so doubling the speed doubles the flow rate.

Which type of pump is most commonly used for high-volume, low-pressure water distribution applications?

Answer: Centrifugal pump

Centrifugal pumps are preferred for high-volume, low-to-moderate pressure applications like water distribution due to their efficiency and simplicity.

The pressure drop due to water flowing through a pipe is primarily a function of:

Answer: Flow velocity, pipe diameter, and pipe length

Friction head loss in a pipe depends on flow velocity, pipe diameter, pipe length, and pipe roughness as described by the Hazen-Williams or Darcy-Weisbach equation.

A water hammer event in a pipeline is best prevented by:

Answer: Installing surge tanks or slow-closing valves

Surge tanks and slow-closing valves absorb pressure transients, preventing the destructive pressure spikes associated with water hammer.