To delay fire alarm system signals facilities, need to follow NFPA 72 requirements, provide requested documents, and follow their authority having jurisdiction’s guidelines. The three approved methods to delay fire alarm system signals include presignal feature, positive alarm sequence, and cross-zoning.
What are the Approved Methods to Delay Fire Alarm System Signals?
Presignal Feature
The presignal feature method delays fire alarm system signals for more than 1 minute. It requires someone to activate the general fire alarm system notifications. First, the initial fire alarm signal immediately sounds at a constantly attended location. These types of locations include department offices, control rooms, fire brigade stations etc. The signal could also transmit to a remote supervising location. Then someone investigates the fire alarm signal and determines whether they need to activate fire alarm system notifications. The presignal feature delays fire alarm system notifications throughout the entire building and may not use any other combination of ways to delay fire alarms.
Positive Alarm Sequence
One of the approved methods to delay fire alarm system signals is a positive alarm sequence. Trained personnel must acknowledge the initial fire alarm system signal at the control panel within 15 seconds otherwise the fire alarm system notifications will activate. Once personnel acknowledges the signal, they have 180 seconds to investigate the issue. Then they must reset or activate the fire alarm within that timeframe. If a second fire detector selected for positive alarm sequence or any other initiating device activates during that time, the system will go into full alarm. The positive alarm sequence can be used for designated devices, sections of a building, or have personnel manually activate or deactivate system for certain situations. Like the presignal feature, positive alarm sequence prohibits multiple types of programmed delays.
Cross-Zoning
Buildings most commonly use cross-zoning to prevent accidental discharge of fire suppression systems. It requires at least two automatic detectors in each protected space. These detectors placement is more closely together than in standard applications. The initial fire alarm signal makes the system go into pre-alarm. If a second detector in the same area transmits a signal, then the fire alarm system signals activate. Delaying fire alarm system signals using cross-zoning has a unique set of challenges. There are very specific guidelines to follow, costly to install, difficult to program, regular service is a lengthy process making it expensive.
Before you decide to delay fire alarm system signals, know that a facility must have a reliable system and a valid reason to delay fire alarm system notifications. Facility’s need to follow NFPA 72 approved methods to delay fire alarm notifications and meet the authority having jurisdiction guidelines. Ultimately, your facility and fire alarm provider will need to work closely with your AHJ to obtain approval.
Categorized in: Education, Fire Alarms, General