CWEA MECHANICAL TECHNOLOGIST
ADVANCED CERTIFICATION EXAM
QUESTIONS AND VERIFIED ANSWERS
1. Which phenomenon occurs when the Net Positive Suction Head Available (NPSHa) falls
below the Net Positive Suction Head Required (NPSHr)?
A. Impeller imbalance
B. Cavitation
C. Thermal expansion
D. Hydraulic locking
Answer: B
Conceptual Explanation: Cavitation occurs when the pressure at the pump inlet drops
below the vapor pressure of the liquid, causing vapor bubbles to form and then collapse
violently.
2. In vibration analysis, a peak at exactly twice the running frequency (2X) in the radial
direction usually indicates which of the following?
A. Structural resonance
B. Bearing outer race defect
C. Angular misalignment
,D. Mechanical looseness
Answer: C
Conceptual Explanation: Angular misalignment is typically characterized by a high 2X
vibration peak in the axial and radial directions.
3. Which type of mechanical seal flush plan utilizes a external source to provide clean, cool
liquid to the seal chamber?
A. API Plan 11
B. API Plan 13
C. API Plan 02
D. API Plan 32
Answer: D
Conceptual Explanation: API Plan 32 involves the injection of a clean fluid from an
external source into the seal chamber to improve the environment for the seal.
4. What is the primary purpose of a ‘wear ring’ in a centrifugal pump?
A. To reduce internal leakage from the discharge to the suction side
B. To increase the structural integrity of the casing
C. To act as a primary bearing for the shaft
D. To balance the axial thrust of the impeller
, Answer: A
Conceptual Explanation: Wear rings provide a replaceable surface that maintains a tight
clearance between the impeller and the casing, minimizing recirculation.
5. When using a dial indicator for shaft alignment, the ‘rim and face’ method primarily
measures which two parameters?
A. Axial float and radial play
B. Torsional twist and vibration
C. Parallel offset and angularity
D. Concentricity and runout
Answer: C
Conceptual Explanation: The rim reading indicates parallel (offset) misalignment, while
the face reading indicates angular misalignment.
6. What does the ISO Viscosity Grade (VG) number of a lubricant represent?
A. Dynamic viscosity at 100 degrees Celsius in Pa-s
B. Kinematic viscosity at 40 degrees Celsius in cSt
C. The pour point of the oil in degrees Fahrenheit
D. The flash point of the oil in degrees Celsius
Answer: B
ADVANCED CERTIFICATION EXAM
QUESTIONS AND VERIFIED ANSWERS
1. Which phenomenon occurs when the Net Positive Suction Head Available (NPSHa) falls
below the Net Positive Suction Head Required (NPSHr)?
A. Impeller imbalance
B. Cavitation
C. Thermal expansion
D. Hydraulic locking
Answer: B
Conceptual Explanation: Cavitation occurs when the pressure at the pump inlet drops
below the vapor pressure of the liquid, causing vapor bubbles to form and then collapse
violently.
2. In vibration analysis, a peak at exactly twice the running frequency (2X) in the radial
direction usually indicates which of the following?
A. Structural resonance
B. Bearing outer race defect
C. Angular misalignment
,D. Mechanical looseness
Answer: C
Conceptual Explanation: Angular misalignment is typically characterized by a high 2X
vibration peak in the axial and radial directions.
3. Which type of mechanical seal flush plan utilizes a external source to provide clean, cool
liquid to the seal chamber?
A. API Plan 11
B. API Plan 13
C. API Plan 02
D. API Plan 32
Answer: D
Conceptual Explanation: API Plan 32 involves the injection of a clean fluid from an
external source into the seal chamber to improve the environment for the seal.
4. What is the primary purpose of a ‘wear ring’ in a centrifugal pump?
A. To reduce internal leakage from the discharge to the suction side
B. To increase the structural integrity of the casing
C. To act as a primary bearing for the shaft
D. To balance the axial thrust of the impeller
, Answer: A
Conceptual Explanation: Wear rings provide a replaceable surface that maintains a tight
clearance between the impeller and the casing, minimizing recirculation.
5. When using a dial indicator for shaft alignment, the ‘rim and face’ method primarily
measures which two parameters?
A. Axial float and radial play
B. Torsional twist and vibration
C. Parallel offset and angularity
D. Concentricity and runout
Answer: C
Conceptual Explanation: The rim reading indicates parallel (offset) misalignment, while
the face reading indicates angular misalignment.
6. What does the ISO Viscosity Grade (VG) number of a lubricant represent?
A. Dynamic viscosity at 100 degrees Celsius in Pa-s
B. Kinematic viscosity at 40 degrees Celsius in cSt
C. The pour point of the oil in degrees Fahrenheit
D. The flash point of the oil in degrees Celsius
Answer: B
