Pumps & Compressors

Question 1

What is the purpose of a pump?

Answer 1

A pump is required to add energy to a liquid to cause the liquid to move against a resistance from one point to another.

Question 2

Define pump suction?

Answer 2

The point where liquid enters the pump.

Question 3

Define Pump discharge?

Answer 3

The point where liquid leaves the pump.

Question 4

Define pump discharge pressure head?

Answer 4

Liquid pressure at the pump discharge.

Question 5

Define pump total pressure head?

Answer 5

Pump discharge pressure minus pump suction pressure. This value represents most of the energy that the pump adds to the liquid. (The pressure added to the liquid by the pump.)

Question 6

Define pump capacity?

Answer 6

The volume of liquid delivered by a pump for a specified period of time.

Question 7

What unit of measure is pump capacity expressed in?

Answer 7

Gallons per minute (GPM).

Question 8

Define air compressor capacity?

Answer 8

Air compressor capacity is the quantity of gas actually delivered when operating between specified inlet and discharge pressures.

Question 9

Define cavitation?

Answer 9

Cavitation is the formation and collapse of vapor bubbles in the pump which causes an increase in pump erosion.

Question 10

Define net positive suction head required?

Answer 10

The pressure, above the vapor pressure of the liquid being pumped, that is required to prevent cavitation.

Question 11

Define net positive suction head available?

Answer 11

The pressure, above the vapor pressure of the liquid being pumped, that is available at the suction of the pump.

Question 12

Define vapor/gas binding?

Answer 12

Vapor/Gas binding is a condition that may occur when vapor/gas collects in a centrifugal pump casing during operation. The vapor/gas cannot be removed from the casing by the impeller. This prevents liquid from entering the casing and therefore prevents proper flow.

Question 13

Define pump runout?

Answer 13

Pump run out occurs when the pump is pumping beyond its design capacity, which is the maximum anticipated flowrate at the lowest anticipated system head. (lots of flow, no pressure)

Question 14

Define Deadhead/Shut-off Head?

Answer 14

Deadhead is a shut-off condition that establishes zero flow and may also be near maximum system head. (lots of pressure, no flow)

Question 15

Define pump priming?

Answer 15

Evacuating air/steam from a pump casing to allow it to fill with liquid.

Question 16

What are the two major classifications of all pumps?

Answer 16

Kinetic and positive displacement.

Question 17

What are the three types of centrifugal pump flow?

Answer 17

Radial flow, mixed flow, axial flow.
Radio flow = high pressure 90°
Axial flow = high flow rate 45°

Question 18

What is the purpose of centrifugal pump multi-staging?

Answer 18

To attain a higher pressure.

Question 19

What are the two types of positive displacement pumps?

Answer 19

Reciprocating and rotary.