CFPS Detection and Alarm Systems 2 — Questions and Answers
Question 1: Under NFPA 72, which wiring class allows a single open or ground fault to render an entire circuit inoperable?
- Class A
- Class B (Correct answer)
- Class C
- Class X
Correct answer: Class B
Class B circuits are not supervised for opens or shorts at every point, so a single fault can disable the entire circuit.
Question 2: A projected beam smoke detector measures which property to detect smoke?
- Ionization chamber current drop
- Reduction in infrared light intensity across a path (Correct answer)
- Air sample particle count
- Rate of temperature rise
Correct answer: Reduction in infrared light intensity across a path
Projected beam detectors measure attenuation of a light beam transmitted across a protected area; smoke reduces the received signal.
Question 3: NFPA 72 defines the Temporal-3 evacuation signal as:
- Three short pulses, pause, repeated (Correct answer)
- Continuous tone
- Slow whoop pattern
- Three long pulses, pause, repeated
Correct answer: Three short pulses, pause, repeated
Temporal Pattern 3 is 0.5-s ON, 0.5-s OFF, 0.5-s ON, 0.5-s OFF, 0.5-s ON, then 1.5-s OFF, repeated continuously.
Question 4: Which initiating device would be MOST appropriate to detect a slow smoldering fire in a large warehouse?
- Fixed-temperature heat detector
- Rate-of-rise heat detector
- Air-sampling (aspirating) smoke detector (Correct answer)
- Ultraviolet flame detector
Correct answer: Air-sampling (aspirating) smoke detector
Air-sampling detectors actively draw air through a pipe network and can detect very low smoke concentrations produced by early-stage smoldering fires.
Question 5: What is the purpose of a duct smoke detector installed in an HVAC return-air duct?
- To activate the building sprinkler system
- To prevent smoke from being recirculated through the HVAC system (Correct answer)
- To measure air velocity in the duct
- To notify occupants to evacuate immediately
Correct answer: To prevent smoke from being recirculated through the HVAC system
Duct detectors shut down the air-handling unit and close dampers to prevent smoke from spreading through the duct system to other areas.
Question 6: According to NFPA 72, a supervisory signal from a sprinkler control valve indicates:
- A fire condition requiring evacuation
- An abnormal condition requiring attention but not immediate evacuation (Correct answer)
- A trouble condition in the alarm system wiring
- Successful system self-test completion
Correct answer: An abnormal condition requiring attention but not immediate evacuation
Supervisory signals indicate off-normal conditions (such as a closed valve) that need correction but do not by themselves require evacuation.
Question 7: A flame detector that responds to radiant energy in the 4.3-micron CO₂ absorption band is classified as:
- Ultraviolet (UV) detector
- Near-infrared (NIR) detector
- Infrared (IR) detector (Correct answer)
- Multi-spectrum infrared detector
Correct answer: Infrared (IR) detector
The 4.3-micron band is a characteristic infrared emission of hot CO₂ produced in hydrocarbon flames, making this an IR flame detector.
CFPS Detection and Alarm Systems 2
Under NFPA 72, which wiring class allows a single open or ground fault to render an entire circuit inoperable?