CWEA MECHANICAL TECHNOLOGIST
GRADE 3 EXAM QUESTIONS AND
VERIFIED ANSWERS
1. A centrifugal pump is running at 1750 RPM and delivering 500 GPM at 100 feet of head. If
the speed is increased to 3500 RPM, what will be the new head according to the affinity laws?
A. 400 feet
B. 300 feet
C. 200 feet
D. 800 feet
Answer: A
Conceptual Explanation: According to pump affinity laws, head varies with the square of
the speed ratio. (3500/1750)^2 = 2^2 = 4. 100 feet * 4 = 400 feet.
2. Which vibration analysis term describes the process of converting a signal from the time
domain to the frequency domain?
A. Harmonic Distortion
B. Resonance Amplification
C. Fast Fourier Transform (FFT)
D. Time Waveform Integration
,Answer: C
Conceptual Explanation: FFT is the mathematical algorithm used to convert a time-
domain vibration signal into its component frequencies for spectral analysis.
3. In a hydraulic system, if the pressure is 1000 PSI and the cylinder piston has an area of 5
square inches, what is the theoretical force generated?
A. 200 lbs
B. 5000 lbs
C. 1000 lbs
D. 500 lbs
Answer: B
Conceptual Explanation: Force = Pressure x Area. 1000 PSI * 5 sq in = 5000 lbs.
4. Which type of bearing failure is characterized by fine, reddish-brown powder and is caused
by minute movements between heavily loaded surfaces?
A. Fretting Corrosion
B. Fluting
C. Spalling
D. True Brinelling
Answer: A
, Conceptual Explanation: Fretting corrosion occurs when surfaces subject to vibration or
slight oscillation undergo oxidation, often appearing as a rust-colored powder.
5. When performing laser alignment on a pump-motor set, why is ‘thermal growth’
considered?
A. To ensure the lubricants maintain proper viscosity
B. To prevent the coupling from melting
C. To account for the ambient temperature of the room
D. To compensate for the expansion of the shaft as the equipment reaches operating
temperature
Answer: D
Conceptual Explanation: Thermal growth refers to the predictable expansion of
machinery components as they heat up to operating temperatures; equipment is often
‘offset’ when cold to be aligned when hot.
6. What is the primary purpose of a lantern ring in a centrifugal pump stuffing box?
A. To provide a seat for the mechanical seal
B. To lock the packing in place
C. To prevent the shaft from vibrating
D. To allow for the introduction of seal water for cooling and lubrication
Answer: D
GRADE 3 EXAM QUESTIONS AND
VERIFIED ANSWERS
1. A centrifugal pump is running at 1750 RPM and delivering 500 GPM at 100 feet of head. If
the speed is increased to 3500 RPM, what will be the new head according to the affinity laws?
A. 400 feet
B. 300 feet
C. 200 feet
D. 800 feet
Answer: A
Conceptual Explanation: According to pump affinity laws, head varies with the square of
the speed ratio. (3500/1750)^2 = 2^2 = 4. 100 feet * 4 = 400 feet.
2. Which vibration analysis term describes the process of converting a signal from the time
domain to the frequency domain?
A. Harmonic Distortion
B. Resonance Amplification
C. Fast Fourier Transform (FFT)
D. Time Waveform Integration
,Answer: C
Conceptual Explanation: FFT is the mathematical algorithm used to convert a time-
domain vibration signal into its component frequencies for spectral analysis.
3. In a hydraulic system, if the pressure is 1000 PSI and the cylinder piston has an area of 5
square inches, what is the theoretical force generated?
A. 200 lbs
B. 5000 lbs
C. 1000 lbs
D. 500 lbs
Answer: B
Conceptual Explanation: Force = Pressure x Area. 1000 PSI * 5 sq in = 5000 lbs.
4. Which type of bearing failure is characterized by fine, reddish-brown powder and is caused
by minute movements between heavily loaded surfaces?
A. Fretting Corrosion
B. Fluting
C. Spalling
D. True Brinelling
Answer: A
, Conceptual Explanation: Fretting corrosion occurs when surfaces subject to vibration or
slight oscillation undergo oxidation, often appearing as a rust-colored powder.
5. When performing laser alignment on a pump-motor set, why is ‘thermal growth’
considered?
A. To ensure the lubricants maintain proper viscosity
B. To prevent the coupling from melting
C. To account for the ambient temperature of the room
D. To compensate for the expansion of the shaft as the equipment reaches operating
temperature
Answer: D
Conceptual Explanation: Thermal growth refers to the predictable expansion of
machinery components as they heat up to operating temperatures; equipment is often
‘offset’ when cold to be aligned when hot.
6. What is the primary purpose of a lantern ring in a centrifugal pump stuffing box?
A. To provide a seat for the mechanical seal
B. To lock the packing in place
C. To prevent the shaft from vibrating
D. To allow for the introduction of seal water for cooling and lubrication
Answer: D
