Welcome back to TPO magazine's Exam Study Guide Series, which offers a pair of water/wastewater study questions with in-depth explanations of the answers. Last time, we covered a set of wastewater and drinking water treatment questions on the topics of Repacking Pumps and Pump Current Signals. This time you can test your knowledge about pump switches and pump shaft rotation.
Wastewater Treatment Sample Question
Which method to turn pumps on or off uses air pressure?
A. Mercury switch (mercoid style)
B. Bubble systems
C. Electrode systems
D. Float switch
Water Treatment Sample Question
In an emergency, the operator bypassed a failed VFD installed on a 2 hp three-phase pump motor by hardwiring the pump’s motor directly to the power source. After doing this, the operator noticed the shaft of the pump was rotating in the wrong direction. How will this affect the equipment?
A. The overloads will trip due to excessively high electrical current
B. The pumps discharge flow rate will be drastically reduced
C. The pump will have an increased flow rate and develop a suction cavitation condition
D. The pump impeller and cooling fan will lock-up or break from being over tightened
To see answers for both of the above questions, click this link.
About the authors: Rick Lallish is the Water Pollution Control program director at the Environmental Resources Training Center (ERTC) of Southern Illinois University-Edwardsville. He provides training for entry-level operators in the wastewater field and operators throughout the state looking to further their education. Lallish was also named the 2017 Illinois Operator of the Year and 2018 president of the Illinois Association of Water Pollution Control Operators.
Drew Hoelscher is the program director of drinking water operations at the Environmental Resources Training Center in Edwardsville, Illinois.
