Fire Alarm Systems Flashcards
7 cards from real FST practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Fire Alarm Systems flashcards as text
What condition causes a 'common cause' failure concern when all detectors on a single initiating device circuit share the same pathway?
Answer: A single fault disabling all devices on that circuit
A common cause failure occurs when one event (such as wire damage) can disable multiple devices simultaneously, undermining system reliability.
Per NFPA 72, voice evacuation messages in high-rise buildings must be intelligible at what minimum speech transmission index (STI) or equivalent metric?
Answer: 0.50
NFPA 72 requires emergency voice/alarm communications to achieve an STI of at least 0.45 (or CIS 0.50 equivalent) to ensure intelligible instructions during emergencies.
A rate-of-rise heat detector will activate when:
Answer: Temperature rises more than 12–15°F per minute
Rate-of-rise heat detectors trigger when temperature increases faster than approximately 12–15°F per minute, indicating a rapidly developing fire.
Which initiating device is MOST appropriate for a parking garage where vehicle exhaust could cause nuisance alarms from smoke detectors?
Answer: Linear heat detector
Linear heat detectors respond only to heat, making them immune to exhaust fumes and appropriate for environments where smoke detectors would generate nuisance alarms.
Under NFPA 72, a fire alarm system at a protected premises must be inspected and tested at what minimum frequency?
Answer: Annually
NFPA 72 requires a minimum annual inspection and test of fire alarm systems, though some components (batteries, supervisory devices) require more frequent testing.
What is the purpose of a 'positive alarm sequence' (PAS) feature in a fire alarm system?
Answer: Provides a delay allowing trained personnel to investigate before general evacuation
Positive alarm sequence allows up to 3 minutes for an initial investigation and 3 more minutes for acknowledgment before triggering full evacuation, reducing false alarm dispatches.
In a fire alarm system, the term 'trouble signal' specifically indicates:
Answer: A fault that could impair system operation
A trouble signal indicates a fault condition — such as an open circuit, low battery, or ground fault — that could prevent the system from functioning properly.