CWEA MECHANICAL TECH GRADE 1
ACTUAL TEST QUESTIONS WITH
COMPLETE ANSWER KEY
●● Mechanical seal failure
Answer: A failure that can occur due to overheating, excessive vibration,
and low flow rates.
●● Air blower
Answer: A device used to supply oxygen to aerobic processes in
wastewater treatment.
●● Motor maintenance checks
Answer: Routine checks that include lubrication of bearings, voltage and
current levels, and alignment with the drive shaft.
●● Corrosion prevention in mechanical components
Answer: Typically achieved using stainless steel due to its resistance to
corrosion.
●● Pump not priming troubleshooting
Answer: Checking the pump's discharge valve to ensure it's fully open.
,●● Cleaning a clogged pump impeller
Answer: Recommended to remove and manually clean the impeller with
a brush.
●● Safety precautions with electrical motors
Answer: Ensuring the motor is properly grounded to prevent electrical
shock.
●● Mechanical strainer function
Answer: To filter out solids from liquids in wastewater treatment.
●● Mechanical strainers
Answer: Mechanical strainers are used to remove large solids and debris
from wastewater before it enters treatment systems, preventing damage
to equipment and ensuring smoother operation.
●● Oil change interval for gear reducers
Answer: Gear reducers should be serviced according to the
manufacturer's guidelines, which often specify an interval for oil
changes, typically between 6 months and 2 years depending on usage.
●● Check valve
,Answer: Check valves allow flow in one direction and automatically
close to prevent backflow, protecting pumps and other equipment from
damage.
●● Cavitation in pumps
Answer: Cavitation occurs when vapor bubbles form in the pump due to
low pressure and then collapse, causing noise, vibration, and potential
damage to the pump.
●● Replacing bearings in a pump motor
Answer: It is crucial to replace bearings with those that match the
original specifications to maintain proper motor function and extend
service life.
●● First check if a pump motor is not starting
Answer: If a pump motor is not starting, the first step should be to check
the power supply and ensure electrical connections are intact and
functioning.
●● Variable frequency drive (VFD)
Answer: A VFD allows for variable speed operation of pumps, which
helps optimize energy usage based on system demand, reducing
electricity costs.
●● Cast iron
, Answer: Cast iron is commonly used for pump impellers due to its
strength, wear resistance, and ability to withstand harsh wastewater
conditions.
●● Sludge conveyor system
Answer: Sludge conveyors are used to move accumulated sludge from
various treatment processes to the dewatering area or disposal site.
●● Running a pump dry
Answer: Running a pump dry can cause severe damage to the pump
components (like the seals and bearings), so it should be turned off as
soon as possible.
●● Expansion joint
Answer: Expansion joints are used to absorb the stresses caused by
thermal expansion or contraction in piping systems, preventing pipe
damage or breakage.
●● Stainless steel
Answer: Stainless steel is commonly used for pump shafts due to its
resistance to corrosion and wear in wastewater environments.
●● Pressure relief valve set point
ACTUAL TEST QUESTIONS WITH
COMPLETE ANSWER KEY
●● Mechanical seal failure
Answer: A failure that can occur due to overheating, excessive vibration,
and low flow rates.
●● Air blower
Answer: A device used to supply oxygen to aerobic processes in
wastewater treatment.
●● Motor maintenance checks
Answer: Routine checks that include lubrication of bearings, voltage and
current levels, and alignment with the drive shaft.
●● Corrosion prevention in mechanical components
Answer: Typically achieved using stainless steel due to its resistance to
corrosion.
●● Pump not priming troubleshooting
Answer: Checking the pump's discharge valve to ensure it's fully open.
,●● Cleaning a clogged pump impeller
Answer: Recommended to remove and manually clean the impeller with
a brush.
●● Safety precautions with electrical motors
Answer: Ensuring the motor is properly grounded to prevent electrical
shock.
●● Mechanical strainer function
Answer: To filter out solids from liquids in wastewater treatment.
●● Mechanical strainers
Answer: Mechanical strainers are used to remove large solids and debris
from wastewater before it enters treatment systems, preventing damage
to equipment and ensuring smoother operation.
●● Oil change interval for gear reducers
Answer: Gear reducers should be serviced according to the
manufacturer's guidelines, which often specify an interval for oil
changes, typically between 6 months and 2 years depending on usage.
●● Check valve
,Answer: Check valves allow flow in one direction and automatically
close to prevent backflow, protecting pumps and other equipment from
damage.
●● Cavitation in pumps
Answer: Cavitation occurs when vapor bubbles form in the pump due to
low pressure and then collapse, causing noise, vibration, and potential
damage to the pump.
●● Replacing bearings in a pump motor
Answer: It is crucial to replace bearings with those that match the
original specifications to maintain proper motor function and extend
service life.
●● First check if a pump motor is not starting
Answer: If a pump motor is not starting, the first step should be to check
the power supply and ensure electrical connections are intact and
functioning.
●● Variable frequency drive (VFD)
Answer: A VFD allows for variable speed operation of pumps, which
helps optimize energy usage based on system demand, reducing
electricity costs.
●● Cast iron
, Answer: Cast iron is commonly used for pump impellers due to its
strength, wear resistance, and ability to withstand harsh wastewater
conditions.
●● Sludge conveyor system
Answer: Sludge conveyors are used to move accumulated sludge from
various treatment processes to the dewatering area or disposal site.
●● Running a pump dry
Answer: Running a pump dry can cause severe damage to the pump
components (like the seals and bearings), so it should be turned off as
soon as possible.
●● Expansion joint
Answer: Expansion joints are used to absorb the stresses caused by
thermal expansion or contraction in piping systems, preventing pipe
damage or breakage.
●● Stainless steel
Answer: Stainless steel is commonly used for pump shafts due to its
resistance to corrosion and wear in wastewater environments.
●● Pressure relief valve set point
