Wastewater Operator Pumps and Equipment Maintenance Questions and Answers

Question 1

An operator performing a routine check on a large centrifugal pump hears a distinct noise similar to gravel or marbles rattling inside the pump casing.
The discharge pressure gauge is also fluctuating erratically.
What is the MOST likely cause of these symptoms?

Accepted Answer

Cavitation occurring inside the volute

Answer

A severe clog in the impeller

Answer

Worn motor bearings

Answer

Pump to motor misalignment

Question 2

A positive displacement pump, such as a progressive cavity pump, is being selected for a sludge pumping application. What is the primary advantage of using this type of pump over a centrifugal pump for this service?

Accepted Answer

It delivers a relatively constant flow rate despite changes in discharge pressure.

Answer

It can run dry for extended periods without damage.

Answer

It requires significantly less maintenance than a centrifugal pump.

Answer

It is less susceptible to damage from abrasive materials.

Question 3

Upon finding a pump motor that is excessively hot and drawing amps significantly above its nameplate rating, what is the correct IMMEDIATE action an operator should take?

Accepted Answer

Immediately shut down, lock out, and tag out the equipment.

Answer

Check the pump for a clog or obstruction while it is running.

Answer

Reduce the flow to the pump using the suction valve.

Answer

Begin lubricating the motor bearings to reduce friction.

Question 4

Which of the following is the primary purpose of a mechanical seal on a centrifugal pump?

Accepted Answer

To control leakage where the rotating shaft exits the stationary pump casing.

Answer

To secure the impeller to the pump shaft.

Answer

To provide a renewable, sacrificial surface between the impeller and casing.

Answer

To prevent air from entering the pump casing during operation.

Question 5

During the replacement of pump packing in a stuffing box, an operator must ensure the lantern ring is correctly positioned. What is the critical function of the lantern ring?

Accepted Answer

To provide a pathway for seal water to lubricate and cool the packing and shaft.

Answer

To prevent the packing rings from being overtightened.

Answer

To act as the final ring that holds the other packing rings in place.

Answer

To automatically adjust the gland follower as the packing wears down.

Question 6

Which of the following routine maintenance tasks is MOST critical for ensuring the long-term health of an electric motor's bearings?

Accepted Answer

Adhering to a proper lubrication schedule with the correct type and amount of grease.

Answer

Measuring the motor's voltage supply weekly.

Answer

Cleaning dirt and debris from the motor's cooling fins.

Answer

Checking the security of the motor's mounting bolts.