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For wide rooms, the candela selection for wall strobes is based primarily on:
Room geometry and mounting height using listed tables
Definition: Use candela tables that account for distance and mounting height to achieve visibility.
Voice systems that share speakers with background music must ensure that:
Fire messages override and take priority
Definition: Emergency messages must pre empt non emergency audio sources.
In sleeping rooms, low frequency sounders are required primarily because:
They awaken sleepers more effectively
Definition: The 520 hertz signal is physiologically more effective at waking sleeping adults.
For mixed occupancy buildings, notification zoning should be:
Coordinated with the egress plan and occupancy use
Definition: Zoning should reflect egress strategy and occupancy to avoid over or under notification.
Strobe lens color for fire alarm notification is typically:
Clear or white
Definition: Fire strobes are generally clear or white; other colors can indicate other hazards per design/approval.
Intelligibility target values commonly used are:
"STI" around 0.50 or "CIS" around 0.70 in "ADS"
Definition: These benchmark values indicate understandable speech in voice systems where required.
If two supplies feed strobes in the same room, they must:
Use a listed sync method to flash together
Definition: Synchronization across supplies maintains consistent visual cues.
To reduce echo induced poor intelligibility in a concourse, the best first step is:
Improve speaker layout and use directional speakers or acoustics
Definition: Managing reflections and coverage patterns typically yields the biggest intelligibility gains.
Spot smoke detector nominal starting spacing on smooth ceilings is commonly:
30 feet
Definition: Thirty feet on center is a common starting point; always follow the detector’s listing and ceiling features.
Corridor detector spacing for corridors up to about 10 feet wide is approximately:
41 feet
Definition: Corridors can use wider intervals due to channelized flow; verify with listings and rules.
Detectors should be kept away from air supply diffusers typically by at least:
3 feet
Definition: Keep smoke detectors out of strong air streams to avoid diluting smoke and delaying response.
Heat detectors are generally preferred over smoke detectors in which area?
Commercial kitchen hood plenum
Definition: In greasy, high vapor areas like hoods, heat detection or special systems are used to avoid nuisance alarms.
Duct smoke detectors on supply systems should be located:
Downstream of filters and ahead of branches
Definition: Detection after filtration and before branch connections detects smoke before distribution.
For very high ceilings with stratification concerns, a good detection choice is:
Beam smoke detectors
Definition: Beam detectors span long distances and can compensate for high ceiling limitations.
Obstructions such as beams may require:
Reducing spacing and adjusting placement
Definition: Beams can create dead air pockets; reduce spacing or relocate to maintain coverage.
When using alarm verification feature, it should be applied primarily to:
Smoke detectors to reduce nuisance alarms
Definition: AVF re checks smoke conditions before latching alarm; do not apply to heat or manual devices.
Duct detector used only for equipment shutdown should signal:
Supervisory
Definition: Equipment control without egress impact annunciate as supervisory, not general alarm.
Pre action sprinkler systems typically interface so that:
Detection opens valve; waterflow creates alarm
Definition: Detection triggers valve opening; waterflow confirms a discharge alarm.
Elevator Phase One recall is commonly triggered by:
Smoke detection in lobbies and machine rooms per design
Definition: Smoke detection at designated locations initiates recall to the primary landing.
Elevator shunt trip, where used, is typically activated by:
Specific heat detection at equipment or hoistway per approved sequence
Definition: Shunt trip relies on heat detection at specific points as engineered and approved.
High airflow data centers often require detection:
Both above ceiling and under raised floor
Definition: Underfloor cables can smolder; provide detection above and below as needed.
Kitchen hood extinguishing system discharge should:
Initiate fire alarm and programmed shutdowns per sequence
Definition: System discharge is a fire event that drives alarm and control actions.
Air sampling detectors are advantageous because they:
Detect very low levels of smoke early
Definition: Aspirating systems sample air continuously and can catch incipient smoke.
Beam detector alignment must be verified using:
Manufacturer alignment tools and obscuration tests
Definition: Follow the device procedure for alignment and sensitivity to ensure reliable operation.
In cold storage, which detection approach is common?
Heat detection or sampling with remote heads
Definition: Low temperatures and stratification favor heat or aspirating detection with remote sampling points.