NYC CUSTODIAN ENGINEER EXAM
REVIEW QUESTIONS AND ANSWERS
1. Which of the following conditions would most likely cause ‘foaming’ in a high-pressure
steam boiler?
A. A sudden decrease in steam demand.
B. Operating with a water level that is too low.
C. High concentration of dissolved solids and alkalinity.
D. Excessive use of oxygen scavenger chemicals.
Answer: C
Conceptual Explanation: Foaming is primarily caused by a high concentration of
dissolved solids, oils, or high alkalinity in the boiler water, which increases surface tension
and prevents steam bubbles from breaking.
2. In a pneumatic control system, what is the primary function of a ‘restrictor’?
A. To increase the air pressure to the actuator.
B. To filter moisture from the main air line.
C. To exhaust air from the system when pressure exceeds a setpoint.
,D. To limit the flow of air to a pilot-operated device or branch line.
Answer: D
Conceptual Explanation: Restrictors are used in pneumatic systems to limit the flow rate
of air to control devices, ensuring stable operation and proper pressure drops across the
circuit.
3. According to NYC Fire Code, what color must the caps of a Siamese connection for a non-
automatic sprinkler system be painted?
A. Red
B. Green
C. Silver
D. Yellow
Answer: C
Conceptual Explanation: In NYC, Siamese connections for non-automatic sprinkler
systems must have silver caps. Red is for standpipe, green is for automatic sprinkler, and
yellow is for combined systems.
4. What is the specific gravity of a fuel oil that is heavier than water?
A. Greater than 1.0
B. Exactly 1.0
C. Less than 1.0
, D. 0.85 to 0.95
Answer: A
Conceptual Explanation: Specific gravity is the ratio of a substance’s density to the
density of water (1.0). If a substance is heavier than water, its specific gravity must be
greater than 1.0.
5. A centrifugal pump is ‘cavitating.’ Which of the following is the most likely cause?
A. Net Positive Suction Head (NPSH) available is lower than required.
B. Discharge head is too high.
C. The pump is rotating too slowly.
D. The packing gland is adjusted too tightly.
Answer: A
Conceptual Explanation: Cavitation occurs when the pressure at the pump inlet drops
below the vapor pressure of the liquid, causing bubbles to form and collapse. This happens
when the available NPSH is insufficient.
6. In a D.C. circuit, Ohm’s Law states that current is equal to:
A. Voltage divided by Resistance.
B. Voltage multiplied by Resistance.
C. Resistance divided by Voltage.
D. Power divided by Resistance squared.
REVIEW QUESTIONS AND ANSWERS
1. Which of the following conditions would most likely cause ‘foaming’ in a high-pressure
steam boiler?
A. A sudden decrease in steam demand.
B. Operating with a water level that is too low.
C. High concentration of dissolved solids and alkalinity.
D. Excessive use of oxygen scavenger chemicals.
Answer: C
Conceptual Explanation: Foaming is primarily caused by a high concentration of
dissolved solids, oils, or high alkalinity in the boiler water, which increases surface tension
and prevents steam bubbles from breaking.
2. In a pneumatic control system, what is the primary function of a ‘restrictor’?
A. To increase the air pressure to the actuator.
B. To filter moisture from the main air line.
C. To exhaust air from the system when pressure exceeds a setpoint.
,D. To limit the flow of air to a pilot-operated device or branch line.
Answer: D
Conceptual Explanation: Restrictors are used in pneumatic systems to limit the flow rate
of air to control devices, ensuring stable operation and proper pressure drops across the
circuit.
3. According to NYC Fire Code, what color must the caps of a Siamese connection for a non-
automatic sprinkler system be painted?
A. Red
B. Green
C. Silver
D. Yellow
Answer: C
Conceptual Explanation: In NYC, Siamese connections for non-automatic sprinkler
systems must have silver caps. Red is for standpipe, green is for automatic sprinkler, and
yellow is for combined systems.
4. What is the specific gravity of a fuel oil that is heavier than water?
A. Greater than 1.0
B. Exactly 1.0
C. Less than 1.0
, D. 0.85 to 0.95
Answer: A
Conceptual Explanation: Specific gravity is the ratio of a substance’s density to the
density of water (1.0). If a substance is heavier than water, its specific gravity must be
greater than 1.0.
5. A centrifugal pump is ‘cavitating.’ Which of the following is the most likely cause?
A. Net Positive Suction Head (NPSH) available is lower than required.
B. Discharge head is too high.
C. The pump is rotating too slowly.
D. The packing gland is adjusted too tightly.
Answer: A
Conceptual Explanation: Cavitation occurs when the pressure at the pump inlet drops
below the vapor pressure of the liquid, causing bubbles to form and collapse. This happens
when the available NPSH is insufficient.
6. In a D.C. circuit, Ohm’s Law states that current is equal to:
A. Voltage divided by Resistance.
B. Voltage multiplied by Resistance.
C. Resistance divided by Voltage.
D. Power divided by Resistance squared.
