Primers

Question 1

What happens when a pump is primed?

Answer 1

The process by which air is forced out of the pump and it is filled with water

Question 2

What are the three methods for priming a pump?

Answer 2

Elevated supply: Water forced in by gravity, pushes air out
Pressure supply: Water forced in by hydrant pressure, air forced out. this is known as SOFT SUCTION
Use of a primer: Only used when working from OPEN WATER. Air is pumped out, causing atmospheric pressure to force the water up into the pump

Question 3

What are the two types of primers?

Answer 3

Exhaust Gas Ejector - used to prime portable pumps.
Water ring primers

Question 4

What is cavitation?

Answer 4

According to Bernoulli’s Law, when velocity goes up, pressure goes down. Centrifugal pump works by acceleration and imparting velocity to the liquid in the eye of the impeller. Under the right conditions, the liquid can boil or vaporize in the eye of the impeller

Question 5

How can cavitation be dealt with?

Answer 5

Reduce engine revs until cavitation stops.

Question 6

As a general rule a centrifugal pump should not experience cavitation when it is located less then how many meters above the water level?

Answer 6

4m