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The type of fire protection equipment used and their technical characteristics are determined by the relevant regulatory documents, GOST, NPB, etc.
Specific recommendations for the use of various types of detectors for various premises are given in the Code of Practice SP 5.13130.2009 “Fire protection systems. Automatic fire alarm and fire extinguishing systems. Design standards and rules”, adopted in 2009.
The appropriateness of using certain systems is determined by the requirements of a specific facility, depending on the tasks performed by the system at the facility, its geometric characteristics, the need to reconfigure and reprogram the system, etc. It should be taken into account that detectors can be located in rooms with very harsh conditions (low or high temperatures, high levels of electromagnetic or mechanical impacts).
The choice of the type of fire alarm is recommended to be made in accordance with its ability to detect various types of smoke, which can be determined according to GOST R 50898, Federal Law of 21.12.1994 69-FZ «On Fire Safety», Federal Law of 22.07.2008 123-FZ «Technical Regulations on Fire Safety Requirements» taking into account the area monitored by one point smoke alarm, and taking into account the maximum distance between alarms, the type of premises. The Code of Practice specifies cases in which the use of addressable and non-addressable systems is permissible. This regulatory document was adopted instead of NPB 88-2001* and has differences from the previous document.
We will briefly analyze some of them.
For example, a clause has been introduced that increases the safety of fire protection systems: “The generation of signals for automatic control of fire extinguishing installations, or smoke removal, or notification, or engineering equipment must be carried out upon the activation of at least two fire detectors, connected according to the logical circuit “AND”. To generate a control command in the protected room or protected zone, there must be at least:
three fire detectors when connected to loops of dual-threshold devices or to three independent radial loops of single-threshold devices;
four fire detectors when connected to two loops of single-threshold devices, with two detectors in each loop;
two fire detectors connected according to the «AND» logic circuit, provided that the faulty detector is replaced in a timely manner;
two fire detectors connected according to the «OR» logic circuit, if the detectors ensure increased reliability of the fire signal.»
The following clause allows: «The generation of control signals for warning systems of types 1, 2, 3 smoke removal, engineering equipment controlled by the fire alarm system, and other equipment, the false triggering of which cannot lead to unacceptable material losses or a decrease in the level of safety of people, is allowed to be carried out upon the triggering of one fire alarm.» However, the criteria for the possibility of «unacceptable material losses or a decrease in the level of safety of people» are not specified. This may allow different authorities to interpret the requirements for the presence of one or two fire alarms differently.
One fire alarm loop with fire alarms that do not have an address is allowed to equip a control zone that includes:
premises located on no more than two communicating floors, with a total area of premises of 300 m2 or less;
up to 10 isolated and adjacent rooms with a total area of no more than 1,600 m2, located on one floor of the building, while the isolated rooms must have an exit to a common corridor, hall, vestibule, etc.;
up to 20 isolated and adjacent rooms with a total area of no more than 1,600 m2, located on one floor of the building, while the isolated rooms must have an exit to a common corridor, hall, vestibule, etc., in the presence of a remote light signaling system for the operation of fire detectors above the entrance to each monitored room;
non-addressable fire alarm loops must connect premises in accordance with their division into protection zones.
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In addition, fire alarm loops must connect rooms in such a way that the time it takes for the duty personnel to determine the location of the fire with semi-automatic control does not exceed 1/5 of the time after which it is possible to safely evacuate people and extinguish the fire. If the specified time exceeds the given value, the control must be automatic.
In all other cases, addressable fire alarms are used.
The Code of Rules also provides tables that determine the distance between different types of detectors in different rooms, and, consequently, their number. This document very strictly stipulates the conditions for the possibility of installing one fire detector in a room.
The area monitored by one point smoke fire detector, as well as the maximum distance between detectors, detector and wall are determined according to Table 1, but do not exceed the values specified in the technical conditions and passports for detectors of specific types.
The distance monitored by linear smoke fire detectors is given in Table 2. The minimum and maximum distance between the emitter and receiver or the detector and reflector are determined by the technical documentation for detectors of specific types.
The emitter and receiver (transmitter and reflector) of a linear smoke fire alarm are installed on walls, partitions, columns and other structures that provide their rigid fastening, so that their optical axis passes at a distance of no less than 0.1 m and no more than 0.6 m from the ceiling level.
When installing the emitter and receiver (transmitter and reflector) of a linear smoke fire alarm, it is necessary to ensure that various objects do not enter the detection zone of the fire alarm during its operation.
The area monitored by one point thermal fire alarm, as well as the maximum distance between the alarms, the alarm and the wall, are determined according to Table 3, but not exceeding the values specified in the technical conditions and passports for the alarms.
Flame fire alarms are installed on ceilings, walls and other building structures of buildings and structures, as well as on process equipment. If smoke emission is possible at the initial stage of a fire, the distance from the detector to the ceiling must be at least 0.8 m. The area of the room or equipment monitored by the flame detector is determined based on the value of the detector's viewing angle, sensitivity according to GOST R 53325, and the sensitivity to flame of a specific combustible material, given in the technical documentation for the detector.
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