CWEA Mechanical Technologist Grade 2 Exam: 300 Questions and Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A
1. What is the primary purpose of a wear ring in a centrifugal pump?
A) To prevent shaft deflection
B) To maintain a close clearance between the impeller and casing
C) To seal the pump shaft
D) To balance axial thrust
Answer: B
Rationale: Wear rings maintain a close running clearance between the impeller and casing to minimize
recirculation and maintain pump efficiency.
2. A nylon faced hammer may be used in equipment assembly to:
A) Prevent electrical shock
B) Reduce hammer replacement costs
C) Reduce rebound or bounce like a regular hammer
D) Prevent damage to surfaces that are struck
Answer: D
Rationale: Nylon faced hammers are used to strike surfaces without causing damage, unlike metal hammers.
3. Which of the following most affects valve life?
A) Preventative maintenance
B) Valve spring strength
C) Size of drive motor
D) Drive motor horsepower
Answer: A
Rationale: Regular preventive maintenance is the most significant factor in extending valve life.
4. The discharge rate of a piston-type pump:
A) Is constant as the main drive RPM changes
B) Is constant at a constant speed
C) Varies inversely with head
,D) Varies with the total dynamic head
Answer: B
Rationale: A piston pump is a positive displacement pump, so its discharge rate is constant at a constant
speed regardless of head.
5. What is the primary cause of cavitation in a centrifugal pump?
A) Excessive discharge pressure
B) Insufficient net positive suction head available (NPSHa)
C) High motor amperage
D) Worn mechanical seal
Answer: B
Rationale: Cavitation occurs when NPSHa drops below NPSHr, causing vapor bubbles to form and collapse
at the impeller eye.
6. A centrifugal pump is operating at 1,750 RPM with an impeller diameter of 10 inches. The pump
produces 500 GPM at 100 feet of head. If the impeller is trimmed to 9 inches, what is the new
approximate flow?
A) 450 GPM
B) 405 GPM
C) 500 GPM
D) 550 GPM
Answer: A
Rationale: Flow varies directly with impeller diameter: Q₂ = Q₁ × (D₂/D₁) = 500 × (9/10) = 450 GPM.
7. A mechanical seal is leaking at a rate of 5 drops per minute. What is the most appropriate initial
action?
A) Immediately replace the seal
B) Tighten the gland follower bolts
C) Monitor the leak and document; if it increases, schedule repair
D) Add seal water to the stuffing box
Answer: C
Rationale: A minor weep (≤5-10 drops/min) is often acceptable; monitor for worsening. Tightening may
damage the seal.
2
,8. What is the purpose of a lantern ring in a packed pump stuffing box?
A) To hold packing in place
B) To distribute seal water or lubricant evenly around the shaft
C) To prevent shaft corrosion
D) To act as a secondary mechanical seal
Answer: B
Rationale: The lantern ring distributes seal water or lubricant uniformly around the shaft to cool and flush
the packing.
9. A three-phase induction motor draws high amperage on all three phases and trips the overload.
The motor is hot to the touch. What is the most likely cause?
A) Single phasing
B) Overload condition (pump running at high flow, low head)
C) Ground fault on one phase
D) Open winding
Answer: B
Rationale: High flow (low head) increases motor load and amperage. Single phasing would cause one phase
to draw zero or very low amps.
10. What is the function of a check valve?
A) To regulate flow
B) To prevent backflow
C) To isolate equipment
D) To relieve pressure
Answer: B
Rationale: Check valves allow flow in only one direction, preventing backflow.
11. The formula for velocity in a pipe is V = Q ÷ __________.
A) Pressure
B) Area
C) Head
3
, D) RPM
Answer: B
Rationale: Velocity equals flow rate divided by cross-sectional area.
12. A lubricant's primary purpose in bearings is to reduce __________.
A) Temperature
B) Vibration
C) Friction
D) Noise
Answer: C
Rationale: Lubrication minimizes metal-to-metal contact and reduces friction.
13. The most common material used for pump shafts is __________ steel.
A) Carbon
B) Stainless
C) Alloy
D) Tool
Answer: B
Rationale: Stainless steel resists corrosion in wastewater environments.
14. The device used to safely lift heavy mechanical equipment is a __________ hoist.
A) Chain
B) Rope
C) Cable
D) Web
Answer: A
Rationale: Chain hoists are commonly used in industrial maintenance for lifting heavy equipment.
15. The process of securing energy sources before maintenance is known as __________.
A) Lockout/Tagout
B) Preventive maintenance
C) Predictive maintenance
4
Rationales 2026 Q&A
1. What is the primary purpose of a wear ring in a centrifugal pump?
A) To prevent shaft deflection
B) To maintain a close clearance between the impeller and casing
C) To seal the pump shaft
D) To balance axial thrust
Answer: B
Rationale: Wear rings maintain a close running clearance between the impeller and casing to minimize
recirculation and maintain pump efficiency.
2. A nylon faced hammer may be used in equipment assembly to:
A) Prevent electrical shock
B) Reduce hammer replacement costs
C) Reduce rebound or bounce like a regular hammer
D) Prevent damage to surfaces that are struck
Answer: D
Rationale: Nylon faced hammers are used to strike surfaces without causing damage, unlike metal hammers.
3. Which of the following most affects valve life?
A) Preventative maintenance
B) Valve spring strength
C) Size of drive motor
D) Drive motor horsepower
Answer: A
Rationale: Regular preventive maintenance is the most significant factor in extending valve life.
4. The discharge rate of a piston-type pump:
A) Is constant as the main drive RPM changes
B) Is constant at a constant speed
C) Varies inversely with head
,D) Varies with the total dynamic head
Answer: B
Rationale: A piston pump is a positive displacement pump, so its discharge rate is constant at a constant
speed regardless of head.
5. What is the primary cause of cavitation in a centrifugal pump?
A) Excessive discharge pressure
B) Insufficient net positive suction head available (NPSHa)
C) High motor amperage
D) Worn mechanical seal
Answer: B
Rationale: Cavitation occurs when NPSHa drops below NPSHr, causing vapor bubbles to form and collapse
at the impeller eye.
6. A centrifugal pump is operating at 1,750 RPM with an impeller diameter of 10 inches. The pump
produces 500 GPM at 100 feet of head. If the impeller is trimmed to 9 inches, what is the new
approximate flow?
A) 450 GPM
B) 405 GPM
C) 500 GPM
D) 550 GPM
Answer: A
Rationale: Flow varies directly with impeller diameter: Q₂ = Q₁ × (D₂/D₁) = 500 × (9/10) = 450 GPM.
7. A mechanical seal is leaking at a rate of 5 drops per minute. What is the most appropriate initial
action?
A) Immediately replace the seal
B) Tighten the gland follower bolts
C) Monitor the leak and document; if it increases, schedule repair
D) Add seal water to the stuffing box
Answer: C
Rationale: A minor weep (≤5-10 drops/min) is often acceptable; monitor for worsening. Tightening may
damage the seal.
2
,8. What is the purpose of a lantern ring in a packed pump stuffing box?
A) To hold packing in place
B) To distribute seal water or lubricant evenly around the shaft
C) To prevent shaft corrosion
D) To act as a secondary mechanical seal
Answer: B
Rationale: The lantern ring distributes seal water or lubricant uniformly around the shaft to cool and flush
the packing.
9. A three-phase induction motor draws high amperage on all three phases and trips the overload.
The motor is hot to the touch. What is the most likely cause?
A) Single phasing
B) Overload condition (pump running at high flow, low head)
C) Ground fault on one phase
D) Open winding
Answer: B
Rationale: High flow (low head) increases motor load and amperage. Single phasing would cause one phase
to draw zero or very low amps.
10. What is the function of a check valve?
A) To regulate flow
B) To prevent backflow
C) To isolate equipment
D) To relieve pressure
Answer: B
Rationale: Check valves allow flow in only one direction, preventing backflow.
11. The formula for velocity in a pipe is V = Q ÷ __________.
A) Pressure
B) Area
C) Head
3
, D) RPM
Answer: B
Rationale: Velocity equals flow rate divided by cross-sectional area.
12. A lubricant's primary purpose in bearings is to reduce __________.
A) Temperature
B) Vibration
C) Friction
D) Noise
Answer: C
Rationale: Lubrication minimizes metal-to-metal contact and reduces friction.
13. The most common material used for pump shafts is __________ steel.
A) Carbon
B) Stainless
C) Alloy
D) Tool
Answer: B
Rationale: Stainless steel resists corrosion in wastewater environments.
14. The device used to safely lift heavy mechanical equipment is a __________ hoist.
A) Chain
B) Rope
C) Cable
D) Web
Answer: A
Rationale: Chain hoists are commonly used in industrial maintenance for lifting heavy equipment.
15. The process of securing energy sources before maintenance is known as __________.
A) Lockout/Tagout
B) Preventive maintenance
C) Predictive maintenance
4
