CWEA MECHANICAL TECHNOLOGIST
GRADE 7 ADVANCED CERTIFICATION
EXAM QUESTIONS AND VERIFIED
ANSWERS
1. According to the pump affinity laws, if the impeller speed of a centrifugal pump is reduced
by 50%, what is the resulting effect on the brake horsepower (BHP) required?
A. BHP is reduced by 50%
B. BHP is reduced by 75%
C. BHP is reduced by 87.5%
D. BHP remains constant
Answer: C
Conceptual Explanation: Power varies with the cube of the speed ratio. (0.5)^3 = 0.125,
which is an 87.5% reduction from the original power.
2. When performing vibration analysis, a large peak at 1x RPM in the axial direction most
likely indicates which of the following mechanical issues?
A. Radial unbalance
B. Vane pass frequency interference
C. Looseness in the bearing housing
,D. Angular misalignment
Answer: D
Conceptual Explanation: Angular misalignment typically produces high axial vibration at
the fundamental running frequency (1x).
3. In the context of Reliability Centered Maintenance (RCM), what does the P-F interval
represent?
A. The time between a potential failure detection and functional failure
B. The period between primary and secondary maintenance tasks
C. The probability of failure over a fixed timeframe
D. The frequency of preventive maintenance lubrication
Answer: A
Conceptual Explanation: The P-F interval is the time between the point where a potential
failure (P) is first detectable and the point where it reaches functional failure (F).
4. Which mechanical seal piping plan uses an external source to provide a clean, cool liquid to
the seal faces at a pressure higher than the process fluid?
A. Plan 32
B. Plan 11
C. Plan 52
D. Plan 53A
, Answer: A
Conceptual Explanation: Plan 32 involves a flush from an external clean source, typically
at a higher pressure to ensure no process fluid enters the seal chamber.
5. What is the primary purpose of a ‘lantern ring’ in a standard stuffing box arrangement?
A. To provide a seat for the mechanical seal
B. To distribute lubrication or cooling water to the packing
C. To act as a sacrificial wear sleeve for the shaft
D. To lock the packing gland in place
Answer: B
Conceptual Explanation: The lantern ring is a spacer that allows seal water or lubricant to
reach the center of the packing set for cooling and lubrication.
6. In a hydraulic system, which phenomenon occurs when the local pressure drops below the
vapor pressure of the liquid, causing bubbles to form and then collapse violently?
A. Water hammer
B. Laminar flow
C. Surge
D. Cavitation
Answer: D
GRADE 7 ADVANCED CERTIFICATION
EXAM QUESTIONS AND VERIFIED
ANSWERS
1. According to the pump affinity laws, if the impeller speed of a centrifugal pump is reduced
by 50%, what is the resulting effect on the brake horsepower (BHP) required?
A. BHP is reduced by 50%
B. BHP is reduced by 75%
C. BHP is reduced by 87.5%
D. BHP remains constant
Answer: C
Conceptual Explanation: Power varies with the cube of the speed ratio. (0.5)^3 = 0.125,
which is an 87.5% reduction from the original power.
2. When performing vibration analysis, a large peak at 1x RPM in the axial direction most
likely indicates which of the following mechanical issues?
A. Radial unbalance
B. Vane pass frequency interference
C. Looseness in the bearing housing
,D. Angular misalignment
Answer: D
Conceptual Explanation: Angular misalignment typically produces high axial vibration at
the fundamental running frequency (1x).
3. In the context of Reliability Centered Maintenance (RCM), what does the P-F interval
represent?
A. The time between a potential failure detection and functional failure
B. The period between primary and secondary maintenance tasks
C. The probability of failure over a fixed timeframe
D. The frequency of preventive maintenance lubrication
Answer: A
Conceptual Explanation: The P-F interval is the time between the point where a potential
failure (P) is first detectable and the point where it reaches functional failure (F).
4. Which mechanical seal piping plan uses an external source to provide a clean, cool liquid to
the seal faces at a pressure higher than the process fluid?
A. Plan 32
B. Plan 11
C. Plan 52
D. Plan 53A
, Answer: A
Conceptual Explanation: Plan 32 involves a flush from an external clean source, typically
at a higher pressure to ensure no process fluid enters the seal chamber.
5. What is the primary purpose of a ‘lantern ring’ in a standard stuffing box arrangement?
A. To provide a seat for the mechanical seal
B. To distribute lubrication or cooling water to the packing
C. To act as a sacrificial wear sleeve for the shaft
D. To lock the packing gland in place
Answer: B
Conceptual Explanation: The lantern ring is a spacer that allows seal water or lubricant to
reach the center of the packing set for cooling and lubrication.
6. In a hydraulic system, which phenomenon occurs when the local pressure drops below the
vapor pressure of the liquid, causing bubbles to form and then collapse violently?
A. Water hammer
B. Laminar flow
C. Surge
D. Cavitation
Answer: D
