CWEA Mechanical Technologist 1
Exam Questions and Answers
A device that moves liquids by transferring kinetic energy. - ANSWER-Centrifugal pump
A failure that can occur due to overheating, excessive vibration, and low flow rates. -
ANSWER-Mechanical seal failure
A device used to supply oxygen to aerobic processes in wastewater treatment. -
ANSWER-Air blower
Routine checks that include lubrication of bearings, voltage and current levels, and
alignment with the drive shaft. - ANSWER-Motor maintenance checks
Typically achieved using stainless steel due to its resistance to corrosion. - ANSWER-
Corrosion prevention in mechanical components
Checking the pump's discharge valve to ensure it's fully open. - ANSWER-Pump not
priming troubleshooting
Recommended to remove and manually clean the impeller with a brush. - ANSWER-
Cleaning a clogged pump impeller
Ensuring the motor is properly grounded to prevent electrical shock. - ANSWER-Safety
precautions with electrical motors
To filter out solids from liquids in wastewater treatment. - ANSWER-Mechanical strainer
function
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. - ANSWER-Mechanical strainers
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. - ANSWER-Oil change interval for gear reducers
Check valves allow flow in one direction and automatically close to prevent backflow,
protecting pumps and other equipment from damage. - ANSWER-Check valve
,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. - ANSWER-
Cavitation in pumps
It is crucial to replace bearings with those that match the original specifications to
maintain proper motor function and extend service life. - ANSWER-Replacing bearings
in a pump motor
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. - ANSWER-First check if a
pump motor is not starting
A VFD allows for variable speed operation of pumps, which helps optimize energy
usage based on system demand, reducing electricity costs. - ANSWER-Variable
frequency drive (VFD)
Cast iron is commonly used for pump impellers due to its strength, wear resistance, and
ability to withstand harsh wastewater conditions. - ANSWER-Cast iron
Sludge conveyors are used to move accumulated sludge from various treatment
processes to the dewatering area or disposal site. - ANSWER-Sludge conveyor system
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. - ANSWER-Running a
pump dry
Expansion joints are used to absorb the stresses caused by thermal expansion or
contraction in piping systems, preventing pipe damage or breakage. - ANSWER-
Expansion joint
Stainless steel is commonly used for pump shafts due to its resistance to corrosion and
wear in wastewater environments. - ANSWER-Stainless steel
The set point for a pressure relief valve should be adjusted based on the maximum
allowable discharge pressure to ensure safe operation and prevent system
overpressure. - ANSWER-Pressure relief valve set point
Screw conveyors are designed to transport thick or wet materials, such as sludge, and
are less likely to clog over long distances. - ANSWER-Screw conveyor
The diaphragm in a diaphragm pump creates a barrier between the inlet and discharge
chambers, allowing the pump to move fluids by creating suction and pressure
alternately. - ANSWER-Diaphragm in a diaphragm pump
, Diffusers are used in aeration tanks to evenly distribute air or oxygen throughout the
water, supporting aerobic biological processes that treat wastewater. - ANSWER-
Diffuser in wastewater treatment
Regular lubrication is essential for pump bearings to reduce friction and wear, extending
the life of the pump and preventing breakdowns. - ANSWER-Lubrication
A shaft coupling connects the motor shaft to the pump shaft while accommodating slight
misalignments and preventing excessive wear on the components. - ANSWER-Shaft
Coupling
Bearing failure often results in abnormal noises like grinding or squealing, which
indicates the bearings are worn or damaged. - ANSWER-Bearing Failure Indication
Strainers are used to filter out large solids from the water, protecting pumps and other
sensitive equipment from damage or clogging. - ANSWER-Strainer Function
Positive displacement pumps are ideal for high-pressure applications because they
move a fixed amount of fluid with each cycle, ensuring steady flow at higher pressures. -
ANSWER-Positive Displacement Pump
Operating a pump at too high a speed can cause cavitation, where vapor bubbles form
and collapse, damaging the pump and reducing efficiency. - ANSWER-Excessive
Cavitation
A drip tray is used to collect any leakage of oil or other fluids from the pump motor to
prevent environmental contamination and maintain safety standards. - ANSWER-Drip
Tray Purpose
The material selected for a pump casing must be resistant to corrosion due to the harsh
nature of wastewater and chemicals present in the system. - ANSWER-Corrosion
resistance of the material
Grease is commonly used to lubricate pump bearings, as it stays in place longer and
reduces the need for frequent reapplication compared to oil. - ANSWER-Grease
A blocked or worn impeller can reduce the pump's ability to move water effectively,
which is a common reason for a decrease in flow rate. - ANSWER-Troubleshooting a
pump not delivering expected flow rate
The mechanical seal is responsible for preventing water or fluid from leaking along the
pump shaft, maintaining a sealed system. - ANSWER-Mechanical seal in a pump
system
Exam Questions and Answers
A device that moves liquids by transferring kinetic energy. - ANSWER-Centrifugal pump
A failure that can occur due to overheating, excessive vibration, and low flow rates. -
ANSWER-Mechanical seal failure
A device used to supply oxygen to aerobic processes in wastewater treatment. -
ANSWER-Air blower
Routine checks that include lubrication of bearings, voltage and current levels, and
alignment with the drive shaft. - ANSWER-Motor maintenance checks
Typically achieved using stainless steel due to its resistance to corrosion. - ANSWER-
Corrosion prevention in mechanical components
Checking the pump's discharge valve to ensure it's fully open. - ANSWER-Pump not
priming troubleshooting
Recommended to remove and manually clean the impeller with a brush. - ANSWER-
Cleaning a clogged pump impeller
Ensuring the motor is properly grounded to prevent electrical shock. - ANSWER-Safety
precautions with electrical motors
To filter out solids from liquids in wastewater treatment. - ANSWER-Mechanical strainer
function
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. - ANSWER-Mechanical strainers
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. - ANSWER-Oil change interval for gear reducers
Check valves allow flow in one direction and automatically close to prevent backflow,
protecting pumps and other equipment from damage. - ANSWER-Check valve
,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. - ANSWER-
Cavitation in pumps
It is crucial to replace bearings with those that match the original specifications to
maintain proper motor function and extend service life. - ANSWER-Replacing bearings
in a pump motor
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. - ANSWER-First check if a
pump motor is not starting
A VFD allows for variable speed operation of pumps, which helps optimize energy
usage based on system demand, reducing electricity costs. - ANSWER-Variable
frequency drive (VFD)
Cast iron is commonly used for pump impellers due to its strength, wear resistance, and
ability to withstand harsh wastewater conditions. - ANSWER-Cast iron
Sludge conveyors are used to move accumulated sludge from various treatment
processes to the dewatering area or disposal site. - ANSWER-Sludge conveyor system
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. - ANSWER-Running a
pump dry
Expansion joints are used to absorb the stresses caused by thermal expansion or
contraction in piping systems, preventing pipe damage or breakage. - ANSWER-
Expansion joint
Stainless steel is commonly used for pump shafts due to its resistance to corrosion and
wear in wastewater environments. - ANSWER-Stainless steel
The set point for a pressure relief valve should be adjusted based on the maximum
allowable discharge pressure to ensure safe operation and prevent system
overpressure. - ANSWER-Pressure relief valve set point
Screw conveyors are designed to transport thick or wet materials, such as sludge, and
are less likely to clog over long distances. - ANSWER-Screw conveyor
The diaphragm in a diaphragm pump creates a barrier between the inlet and discharge
chambers, allowing the pump to move fluids by creating suction and pressure
alternately. - ANSWER-Diaphragm in a diaphragm pump
, Diffusers are used in aeration tanks to evenly distribute air or oxygen throughout the
water, supporting aerobic biological processes that treat wastewater. - ANSWER-
Diffuser in wastewater treatment
Regular lubrication is essential for pump bearings to reduce friction and wear, extending
the life of the pump and preventing breakdowns. - ANSWER-Lubrication
A shaft coupling connects the motor shaft to the pump shaft while accommodating slight
misalignments and preventing excessive wear on the components. - ANSWER-Shaft
Coupling
Bearing failure often results in abnormal noises like grinding or squealing, which
indicates the bearings are worn or damaged. - ANSWER-Bearing Failure Indication
Strainers are used to filter out large solids from the water, protecting pumps and other
sensitive equipment from damage or clogging. - ANSWER-Strainer Function
Positive displacement pumps are ideal for high-pressure applications because they
move a fixed amount of fluid with each cycle, ensuring steady flow at higher pressures. -
ANSWER-Positive Displacement Pump
Operating a pump at too high a speed can cause cavitation, where vapor bubbles form
and collapse, damaging the pump and reducing efficiency. - ANSWER-Excessive
Cavitation
A drip tray is used to collect any leakage of oil or other fluids from the pump motor to
prevent environmental contamination and maintain safety standards. - ANSWER-Drip
Tray Purpose
The material selected for a pump casing must be resistant to corrosion due to the harsh
nature of wastewater and chemicals present in the system. - ANSWER-Corrosion
resistance of the material
Grease is commonly used to lubricate pump bearings, as it stays in place longer and
reduces the need for frequent reapplication compared to oil. - ANSWER-Grease
A blocked or worn impeller can reduce the pump's ability to move water effectively,
which is a common reason for a decrease in flow rate. - ANSWER-Troubleshooting a
pump not delivering expected flow rate
The mechanical seal is responsible for preventing water or fluid from leaking along the
pump shaft, maintaining a sealed system. - ANSWER-Mechanical seal in a pump
system
