CIT - Certified Irrigation Technician Hydraulics and Water Management Questions and Answers

Question 1

An irrigation system is experiencing loud banging noises in the mainline whenever a large, fast-closing electric zone valve shuts off.
What is the MOST effective long-term solution to mitigate this issue?

Accepted Answer

Install a water hammer arrestor near the valve.

Answer

Install a pressure regulator before the valve.

Answer

Increase the static pressure of the system.

Answer

Replace the mainline with a smaller diameter pipe.

Question 2

If the flow rate (GPM) in a given size of PVC pipe is doubled, what is the approximate effect on the friction loss per 100 feet of that pipe?

Accepted Answer

It increases by approximately four times.

Answer

It is cut in half.

Answer

It doubles.

Answer

It remains the same.

Question 3

To prevent excessive friction loss and the damaging effects of water hammer, what is the generally accepted maximum design velocity for water in PVC irrigation mainlines?

Accepted Answer

5 feet per second (fps)

Answer

2 feet per second (fps)

Answer

8 feet per second (fps)

Answer

10 feet per second (fps)

Question 4

A technician is calculating the Total Dynamic Head (TDH) for a pump application. Which of the following factors is considered part of the dynamic head calculation, but NOT the static head?

Accepted Answer

The friction loss through pipes, valves, and fittings.

Answer

The vertical elevation change from the water source to the highest sprinkler head.

Answer

The pressure required at the sprinkler head for proper operation.

Answer

The pressure of the water at the source (e.g., in a pressurized municipal line).

Question 5

A 25-year-old irrigation system with an unlined cast iron mainline is being evaluated. When calculating the current system's expected friction loss, what is the most important adjustment a technician should make compared to calculations for a new PVC system?

Accepted Answer

Use a lower C-Factor value in the friction loss calculations.

Answer

Assume a higher static water pressure.

Answer

Use a higher C-Factor value in the friction loss calculations.

Answer

Disregard the pipe material and only use the pipe's diameter.

Question 6

An irrigation system has a static pressure of 80 PSI at the backflow preventer. The total pressure loss from elevation change is 5 PSI. The friction loss through the mainline and zone valve is 11 PSI. The friction loss through the lateral lines for that zone is 9 PSI. What is the available dynamic pressure at the base of the sprinkler heads in that zone?

Accepted Answer

55 PSI

Answer

69 PSI

Answer

60 PSI

Answer

80 PSI

An irrigation system is experiencing loud banging noises in the mainline whenever a large, fast-closing electric zone valve shuts off.What is the MOST effective long-term solution to mitigate this issue?

An irrigation system is experiencing loud banging noises in the mainline whenever a large, fast-closing electric zone valve shuts off.
What is the MOST effective long-term solution to mitigate this issue?