FPE Fire Detection & Alarm Systems 2 — Questions and Answers
Question 1: What is the primary purpose of a duct smoke detector installed in an HVAC air handling unit?
- To activate the sprinkler system when smoke is detected
- To detect smoke in the airstream and shut down the air handling unit (Correct answer)
- To alert occupants in the occupied space below the ductwork
- To measure air temperature for fire modeling purposes
Correct answer: To detect smoke in the airstream and shut down the air handling unit
Duct smoke detectors sense smoke within the HVAC airstream and initiate shutdown of air handling equipment to prevent smoke from being recirculated or distributed throughout the building.
Question 2: Which of the following is classified as a notification appliance rather than an initiating device in a fire alarm system?
- Duct smoke detector
- Waterflow alarm switch
- Strobe light alarm device (Correct answer)
- Manual pull station
Correct answer: Strobe light alarm device
A strobe light is a notification appliance that alerts occupants after the alarm is initiated; it outputs a signal rather than detecting a fire condition.
Question 3: What is the primary operational advantage of an addressable fire alarm system over a conventional zoned system?
- Lower installation material costs
- Ability to pinpoint the exact device that initiated an alarm (Correct answer)
- Higher detector sensitivity across all device types
- Elimination of the need for periodic testing
Correct answer: Ability to pinpoint the exact device that initiated an alarm
In addressable systems, each device has a unique address allowing the control panel to identify the exact location of the initiating device, rather than only identifying which zone activated.
Question 4: What does alarm verification in a fire alarm control panel accomplish?
- Confirms that the fire department has acknowledged the alarm
- Delays retransmission by re-sampling the detector to reduce false alarms (Correct answer)
- Verifies that all notification appliances are operating at correct sound levels
- Tests the integrity of battery backup power after an alarm event
Correct answer: Delays retransmission by re-sampling the detector to reduce false alarms
Alarm verification causes the FACP to wait and re-sample a smoke detector signal before sounding a full alarm, reducing nuisance alarms from transient non-fire conditions such as cooking vapors.
Question 5: A Digital Alarm Communicator Transmitter (DACT) in a fire alarm system transmits signals over which infrastructure?
- Dedicated leased telephone lines
- Public switched telephone network (PSTN) (Correct answer)
- Radio frequency licensed spectrum
- Fiber optic backbone cabling
Correct answer: Public switched telephone network (PSTN)
A DACT transmits encoded alarm signals over the public switched telephone network (PSTN) to a digital alarm communicator receiver at a monitoring station.
Question 6: Under NFPA 72, a Positive Alarm Sequence (PAS) allows what specific action before a full alarm is transmitted?
- An authorized person has up to 15 seconds to investigate and reset the detector (Correct answer)
- The building automation system automatically verifies the fire event
- The sprinkler system activates before the audible alarm sounds
- A second detector in the same zone must also activate before the alarm sounds
Correct answer: An authorized person has up to 15 seconds to investigate and reset the detector
Positive Alarm Sequence (PAS) permits an authorized person up to 15 seconds after initial detector activation to acknowledge and investigate before the system enters full alarm, helping reduce nuisance alarms.
Question 7: What is the function of the notification appliance circuit (NAC) in a fire alarm system?
- Carries detection signals from initiating devices to the control panel
- Provides power and supervision to audible and visual alarm devices (Correct answer)
- Connects the fire alarm panel to the central monitoring station
- Monitors wiring integrity of smoke detector circuits
Correct answer: Provides power and supervision to audible and visual alarm devices
The notification appliance circuit (NAC) supplies power and provides supervisory monitoring to audible and visual notification devices such as horns, speakers, and strobe lights.
FPE Fire Detection & Alarm Systems 2
What is the primary purpose of a duct smoke detector installed in an HVAC air handling unit?