Fire Alarm & Detection Systems Flashcards

Under NFPA 72, what is the maximum allowable spacing between smoke detectors on a smooth ceiling with no obstructions?

Answer: 50 feet

NFPA 72 allows smoke detector spacing up to 50 feet between detectors on smooth ceilings.

A heat detector rated at 135°F (57°C) is classified as which type?

Answer: Fixed-temperature only

A detector rated at a specific temperature threshold (135°F) without a rate-of-rise element is a fixed-temperature detector.

Which NFPA standard governs the installation of fire alarm systems in the United States?

Answer: NFPA 72

NFPA 72, the National Fire Alarm and Signaling Code, governs the installation, inspection, testing, and maintenance of fire alarm systems.

What is the primary purpose of a 'supervisory signal' in a fire alarm system?

Answer: Alert personnel to an off-normal condition in a fire protection system

A supervisory signal indicates that a fire protection system or component (such as a sprinkler control valve) is in an off-normal condition.

Beam-type smoke detectors are best suited for protecting which type of area?

Answer: Large open areas with high ceilings such as atriums or warehouses

Projected beam smoke detectors are ideal for large open spaces with high ceilings where installing point-type detectors would be impractical.

What does a 'Class A' wiring style provide in a fire alarm system that 'Class B' does not?

Answer: Fault tolerance through a return path, allowing operation during a single open-circuit fault

Class A wiring loops back to the control panel, so a single break in the circuit does not disable devices beyond the fault point.

An inspector finds that a duct smoke detector's sampling tube is clogged with dust. What is the immediate concern?

Answer: The detector may fail to detect smoke in the HVAC duct

A clogged sampling tube prevents smoke-laden air from reaching the sensing chamber, making the detector unable to respond to a real fire event.