Commercial Fire Systems: General Requirements
Commercial fire alarm systems are required as a condition of obtaining a "certificate of occupancy" before a business can open. The National Fire Alarm Code (NFPA72) is enforced by the Fire Marshal, otherwise known as the "authority having supervision" (AHJ). Design plans for the fire alarms must be submitted by a NICET-certified individual for approval by the AHJ before the work begins. Citadel Security Systems has forty-five years of experience helping business owners create and execute these plans, and is well-qualified to help get you on your way to opening day.
Smoke detectors will almost always be required, What needs to be determined is how many and where they should be placed. Smoke detectors detect particles of smoke in the early stages of fire. The layout of the building will determine how many smoke detectors will be required and where they should be placed.
Open area heat detectors activate at 135°F. Heat detectors are for areas in which smoke detectors would not perform well, such as cold unheated warehouses or dusty areas. High temperature heat detectors (194°F) are designed for attic applications, where temperatures can regularly reach 150°F.
Manual Pull Stations
Manual pull stations provide a means of signaling the remaining occupants of a building a fire situation. They are installed near the exit doors and on all levels of the building. For schools and gymnasiums, plastic covers with their own built-in sounders may be prescribed by the AHJ as a deterrent to mischievous students.
Projected Beam Smoke Detectors
In high ceilings areas, lobbies, gymnasiums, or large atrium situations, it may not be practical to locate conventional smoke detectors on the ceiling. For these situations, projected beam smoke detectors can guard large areas by emanating a beam of light to a receiver at the other end. One projected beam smoke detector can protect a large area that would have required dozens of smoke detectors. They sense "light obscuration" across their field of view to activate. Total blockage is rejected as being a fire signal, and results in a "trouble" signal instead. Trouble signals do not result in the dispatch of fire authorities.
Elevator Recall Smoke Detectors
Smoke detectors located outside elevators can be designated to "recall" the elevator to ground level so that no one gets trapped in the elevator during a fire. Responding firefighters can override elevator control with an override key as they deem appropriate.
HVAC Duct Detectors
Smoke detectors located in the ductwork of the heating and air conditioning system prevent smoke from being transmitted throughout the building. Upon activation, they automatically shut down the fan of the heating & air conditioning unit to stop the spread of smoke to other areas.
Horn/Strobes alert the occupants of a building during a fire by producing a distinct audible sound along with a flashing light (for the benefit of the hearing impaired). Proper placement must be designed by a "NICET-qualified" individual to fulfill the audibility requirement and adequate light dispersion.
The fire code does not address the need for an outdoor horn/strobe. The reason is, if someone is already outside, there is no evacuation notification necessary. However, the local AHJ may specify an outdoor horn/strobe so that responding firefighters can locate the affected building more quickly, before any flames are visible.
Strobe Only (For Bathrooms)
The federal Americans With Disabilities Act (ADA) requires that hearing-impaired persons must have adequate notification of fire situations. Hence, a strobe (without a horn) is required in all commercial bathrooms.
Sprinkler & Flow Valve Monitoring
Flow valves and sprinkler water flow valves must be monitored for actual water flow. If a sprinkler head activates, the water flow valve will sense the flow of water in the pipe, and the central monitoring station will respond with a dispatch of the fire department.
"Wet" sprinkler systems consist of pressurized water in pipes held back by sprinkler heads. Water is held back by a piece of of solder that melts at 135°F. If the solder melts, water will squirt through the orifice of the sprinkler head to extinguish the fire.
Wet sprinkler systems cannot be used in unheated warehouses because the water would freeze in the pipes below 32°F, causing the pipes to burst. Hence, "dry" sprinkler systems are specified that pressurize the pipes with air, holding back the water. If a sprinkler head "pops", the air escapes, and water flows through the pipes to extinguish the fire. With a dry sprinkler system, air pressure in the pipes must be supervised.