WTO Equipment Maintenance & Troubleshooting 3

Question 1

An operator notices that a backwash flow rate has decreased significantly over several weeks despite no changes to settings. What is the most probable cause?

Accepted Answer

Backwash pump impeller or strainers are partially clogged

Answer

Gradual reduction in backwash flow usually indicates fouling or wear in the backwash pump, its strainers, or the supply piping.

Question 2

What is the primary purpose of a check valve installed on the discharge side of a pump?

Accepted Answer

To prevent backflow when the pump stops

Answer

Check valves allow flow in one direction only, preventing water from flowing backward through the pump when it is shut down.

Question 3

During a routine check, an operator finds that a chemical feed pump is running but delivering no chemical. Which cause should be investigated first?

Accepted Answer

The chemical supply tank is empty or the suction line is air-locked

Answer

An empty chemical tank or air in the suction line are the most common reasons a metering pump runs but delivers nothing.

Question 4

A mechanical seal on a centrifugal pump is leaking more than a slow drip. What should the operator do?

Accepted Answer

Schedule immediate seal replacement

Answer

Excessive leakage from a mechanical seal indicates seal face wear or failure; the seal must be replaced to prevent further damage and chemical contamination.

Question 5

Which condition would cause a pressure relief valve to open repeatedly during pump operation?

Accepted Answer

Discharge pressure exceeds the relief valve set point

Answer

A relief valve opens when discharge pressure exceeds its set point, which may indicate a closed valve, excessive system resistance, or an oversized impeller.

(WTO) Water Treatment Operator Certification Practice Test

(WTO) Water Treatment Operator Certification Practice Test

WTO Equipment Maintenance & Troubleshooting 3