Installation of the required number of fire detectors in the room. How many fire detectors should there be in a room: rules and regulations? Standards for installing fire detectors in apartments

Fire detectors are installed only in accordance with developed standards and regulations, compliance with which must be strictly observed. The number and order of arrangement of sensors is prescribed in the set of installation rules dated 2009 (SP 5.13130.2009). The response time of the detectors, as well as the timely evacuation of people, depends on how competently the installation of all fire alarm sensors is carried out.

Regardless of the type of alarm sensor (smoke, heat, flame, etc.), it is recommended to place at least two devices in the same room for more reliable data and to eliminate the possibility of false alarms.

Rules for placing smoke devices

Point type optical smoke detectors are used in medium or small rooms residential buildings, hospitals, hotels, etc.

Linear smoke detectors are used to control large premises: halls, warehouses, halls, airport terminals.

When installing sensors, the characteristics of gas mixtures and the presence of air flows from ventilation shafts or heating devices are taken into account. Some gases (chlorine, butane) concentrate near the floor, but under the influence warm air may accumulate under the ceiling.

The exact location of the detector (near the floor, near the ceiling) is determined by its settings for capturing a specific gas and is indicated in the product passport.

Placement of autonomous detectors

These sensors are used in everyday life to protect living rooms in private houses, apartments, hotel rooms, etc.

One autonomous fire detector covers about 30 sq.m. controlled area, so one device, as a rule, is enough for one room.

Autonomous devices are mounted in an open ceiling space with good air circulation. Installation above doors and in remote corners of the room is not recommended. It is also not advisable for the autonomous detector to be exposed to direct sunlight.

If it is not possible to install the device on the ceiling, then it can be placed on the walls, and the distance to the ceiling should be within 10 - 30 cm.

If there are protrusions in the ceiling space of more than 8 cm, then the controlled area of ​​the device is reduced by 25%.

Installation of light, sound and voice alarms

The fire safety of the building is ensured not only by detectors, but also by information light displays and sound alarms, facilitating the rapid and organized evacuation of people.

The installation of such alarms is also regulated by regulatory documents. Requirements for the installation site of the light board:

Sound alarms can be located both inside and outside the building. They are mounted under the ceiling - 15 cm to the ceiling, at a distance of 2-2.3 meters from the floor.

Fire alarm systems cannot exist without sensitive elements of the system: fire detectors, which actually detect a fire.

Type of recognizable fire sign

A fire can be recognized by various signs, and accordingly there are detectors:

• smoke (here the sensor detects leaking smoke),
• flame (the detector detects the presence of a flame),
• thermal (the sensor recognizes an increase in temperature characteristic of a fire),
• gas (reacting to gas) and
• combined (combining the above four points).

The combustion of different materials occurs in different ways: some at high combustion temperatures do not emit smoke, some, on the contrary, emit black flakes of soot, and some only smolder without showing a flame. In accordance with what materials are located at the site, it is necessary to install fire detectors, the classification of which makes it possible to detect the corresponding type of combustion.

Smoke detectors themselves are divided into ionization, optical and linear.

Flame sensors, in turn, are divided into classes from 1st to 4th in accordance with their flame detection range. Class 4 “sees” the flame within 8 meters around itself, while class 1 sees flames within 25 meters or more.

Thermal sensors are divided into a) maximum (those that sound the alarm when the temperature reaches the upper permissible threshold), b) differential (those that respond to a certain rate of temperature increase) and c) maximum-differential. Also heat detectors classified according to their speed of operation.

There are also manual call points that start working when a person who notices the fire presses a button or turns a lever. In this case, the sensitive element is the person himself, who activating the detector reports about the fire system.

Nutrition method

According to the method of generating electricity, fire detectors are divided into:

• those that are powered via a loop, that is, via a common cable together with other devices on the network,
• those that are fed through a separate channel, and
• those that are self-powered.

The choice of power supply is important when the site has difficult conditions for laying cables or when cables are located in areas highly susceptible to fire. The owner will have to choose between the cost of installation, the beauty of the interior and the reliability of the alarm.

Principle of signal generation

Fire detectors are divided into two types based on how exactly they detect danger. These are detectors

• active (those that themselves send a signal into the environment and then react to its change) and
• passive (who wait until the fire sign itself reaches from the location).

Location capability

When fighting a fire, it is sometimes very useful to know at what point exactly the fire occurred, at what stage it is in a particular room, and how it spreads. Addressable detectors help determine this. In contrast, there are addressless detectors, which only notify that there is a fire. The difference between such detectors is the price and type of installed system.

Type of controlled area

According to this classification, fire detectors are divided into

• point (detector receiving data at one point),
• linear (danger is recognized using a beam line between two devices),
• volumetric (controlling a certain amount of space from their location) and
• combined.

When choosing these detectors, the volume of the room, the specifics of its configuration and some other factors, including price, are taken into account.

Fire detectors (FI).

Selecting a detector depending on the type of premises and operating conditions.

Automatic fire detectors are divided according to the type of signal transmission:

• dual-mode detectors with one output for transmitting a signal both about the absence and presence of signs of fire;
• multi-mode detectors with one output for transmitting a limited number (more than two) types of signals about the rest state, fire alarm or other possible conditions;
• analogue detectors, which are designed to transmit a signal about the value of the fire sign they control, or an analogue/digital signal, and which is not a direct fire alarm signal.

The symbol for fire detectors must consist of the following elements: IP Х1Х2Х3-Х4-Х5.

The abbreviation IP defines the name “fire detector”. Element X1 - indicates a controlled sign of fire; Instead of X1, one of the following digital designations is given:

1 - thermal;

2 - smoke;

3 - flame;

4 - gas;

5 - manual;

6…8 - reserve;

9 - when monitoring other signs of fire.

Element X2X3 denotes the operating principle of the PI; instead of Х2Х3 one of the following digital designations is given:

01 - using the dependence of the electrical resistance of the elements on temperature;

02 - using thermo-EMF;

03 - using linear expansion;

04 - using fusible or combustible inserts;

05 - using the dependence of magnetic induction on temperature;

06 - using the Hall effect;

07 - using volumetric expansion (liquid, gas);

08 - using ferroelectrics;

09 - using the dependence of the elastic modulus on temperature;

10 - using resonant-acoustic methods of temperature control;

11 - radioisotope;

12 - optical;

13 - electrical induction;

14 - using the “shape memory” effect;

15…28 - reserve;

29 - ultraviolet;

30 - infrared;

31 - thermobarometric;

32 - using materials that change optical conductivity depending on temperature;

33 - aeroionic;

34 - thermal noise;

35 - when using other operating principles.

Element X4 indicates the serial number of development of a detector of this type.

Element X5 indicates the class of the detector.

The choice of detector type, unfortunately, is often made based on its cost, and not on the criterion of the maximum level of protection of people from fire and ensuring the limitation of material losses while protecting property. The recommendations given in the standards are very limited and do not take into account modern technologies for detecting lesions of various types. Using traditional threshold systems also limits the ability to optimize detection performance. Obviously, the addressable analogue system has the greatest potential for ensuring early detection of a fire hazardous situation in the absence of false alarms, provided that the maximum range of addressable analogue detectors is used. Currently widely used multisensory detectors (not to be confused with combined), for example, smoke and gas CO detectors with a thermal sensor to adjust sensitivity, as well as smoke and gas CO detectors with a thermal sensor.

FIRE FACTORS

The fire is accompanied various processes, including those of a destructive nature, such as charring, deformation and cracking of building structures, the presence of high temperatures and hot toxic smoke. But these factors appear too late in a fire to be used to prevent the loss of people or property. The purpose of a fire alarm is to detect factors that arise at an early stage of the development of a fire, so that there is enough time to evacuate people and take measures to localize the source and prevent further development of the fire into a destructive stage. Unfortunately, there is no single factor that would arise at the early stage of development of all types of fires and that could be used to create a universal fire detector. Each type of fire is accompanied by various factors at the initial stage of development, depending on the nature of the combustion products and the conditions for the formation of the fire. Burning aerosols (combustion of evaporated fuel), smoke particles, toxic gases, as well as heat in the form of a convective jet of hot gases in the presence of a radiated component may occur.

TYPES OF FOCI

It is possible to classify outbreaks depending on the environment in which they may occur, according to factors that will ensure their earliest detection. Thus, fires can be divided into two main types - fast burning, which is characterized by the appearance of fire immediately after ignition, and slow burning, in which initial stage There may be no flame at all, but there will be a significant release of smoke or carbon monoxide CO. These basic types of fires can be further divided into types of ignition, flammability of the material, and relative availability of fuel and oxygen. Fast open fires usually produce aerosols, flames appear and heat is generated. In this case, smoke, as a rule, consists of invisible small particles and can be present in the form of haze over the fire, but it can also be visible, often dark in color, especially when burning liquid hydrocarbons or foam.

Slow burning-smoldering fires tend to have higher levels of visible smoke, which is composed of particles bigger size and from toxic gases with low temperatures and low levels of thermal radiation. Smoke can vary in color, but most smoldering solid hydrocarbon fires are likely to have white smoke initially. Descriptions of both fast- and slow-burning fire types can be misleading because some slow fires can reach dangerous proportions faster than fast fires, and they can often be more life-threatening due to high levels of toxic gases. During fires in 2011 in Russia, 8,378 people died due to exposure to combustion products (70.0% of the total number of deaths), and from exposure high temperature– 898 people (7.5%). Thus, it is necessary to ensure a minimum detection time for both fast and slow foci. It should be noted that real outbreaks, as a rule, are complex systems, combining elements of both types of foci. Although there are cases where in the early stages of a fire there is only smoldering, it is less likely for open fires that the fire will not quickly spread to adjacent material, which produces visible smoke and toxic products when burned.

Chemical fires that are limited to one type of fuel may conflict with these general patterns, for example, phosphorus burns extremely quickly, and at the same time creates very dense white smoke. In such cases, additional information must be used to select the most appropriate detector type.

REGULATORY REQUIREMENTS

Recommendations for choosing the type of detector depending on the purpose of the protected premises and the type of fire load are given in Table M.1 of Appendix M to SP 5.13130.2009 and are limited to three types of automatic detectors: smoke, heat and flame. For most premises, 2–3 types of detectors are indicated without indicating priorities; there are no comments for choosing the optimal type of detector. Table M.1 has been rewritten practically unchanged for about 30 years from the original table of Appendix 3 SNiP 2.04.09-84 to NPB 88-2003 and further to SP 5.13130.2009, despite the wide range of gas, aspiration and multisensory detectors from domestic and foreign manufacturers.

About 15 years ago, buildings and premises were identified that should only be protected by smoke detectors. Appendix A (mandatory) SP 5.13130.2009 states: “Buildings and premises listed in paragraphs 3, 6.1, 7, 9, 10, 13 of Table 1, paragraphs 14–19, 26–29, 32–38 of Table 3, with the use of automatic fire alarms should be equipped with smoke detectors." These are, firstly, buildings where it is necessary to protect people from fire: dormitories, specialized residential buildings for the elderly and disabled, buildings for public and administrative purposes, premises for administrative and public purposes, built-in and attached, buildings of trade enterprises and premises of trade enterprises, built-in and built-in and attached to buildings for other purposes, exhibition halls and exhibition pavilion buildings. Secondly, buildings with radio-electronic equipment and communications equipment: technical workshops of terminal amplification points, intermediate radio relay stations, transmitting and receiving radio centers, hardware rooms of base stations of the cellular mobile radio communication system and hardware rooms of radio relay stations of the cellular mobile radio communication system, premises of the main ticket offices, premises of the control bureau transfers and zonal computer centers of post offices, postal communication centers, automatic telephone exchange halls, where switching equipment of quasi-electronic and electronic types together with a computer used as a control complex, input-output devices, premises for electronic switching stations, nodes, documentary telecommunication centers, dedicated premises for computer-based control devices of automatic long-distance telephone exchanges, premises for placing electronic computers operating in control systems complex technological processes, communication processors (server), archives of magnetic and paper media, plotters, printing information on paper (printer) and for placing personal Computers on user desktops. Thirdly, archives and storage facilities: premises for storing and issuing unique publications, reports, manuscripts and other documentation of special value (including archives of operational departments), storage premises and premises for storing service catalogs and inventories in libraries and archives, premises for storing museum valuables, premises for processing, sorting, storage and delivery of parcels, written correspondence, periodicals, insurance mail, premises (lockers) for storing hand luggage and warehouses of flammable materials in railway stations and air terminals, premises for storing flammable materials or in flammable packaging when located under the stands in indoor and outdoor sports facilities, in buildings of indoor sports facilities, premises for production and storage purposes located in research institutions and others public buildings, as well as filming pavilions of film studios.

Smoke detectors are understood to provide earlier detection compared to heat and flame detectors. However, their operating principle and the low requirements of GOST R 53325 for protection against interference determine a high probability of false alarms, which leads to the need not only for additional equipment costs, but also for a significant amount of time to increase the reliability of signals. The requirement to detect a fire at the same time by two detectors, separated by a considerable distance, with ventilation and air conditioning systems running, is very problematic. In addition, the standards have not yet introduced requirements for the need to install duct smoke detectors on exhaust ventilation, into which most of the smoke goes, quickly spreading throughout the entire building in the event of a fire. As a result, despite the use of smoke detectors, early detection of outbreaks is not ensured.

CLASSIC FIRE DETECTORS

Optical smoke detectors can operate using optical smoke scattering or dimming effects. Today, the dimming effect is used in linear smoke detectors, and in point smoke detectors, the light scattering effect is most widely used. When using LED and photodiode IR range At a certain angle in the smoke chamber, these detectors are effective in detecting visible smoke particles. Invisible smokes in the form of aerosols with much smaller particle sizes are difficult to detect with optical smoke detectors. Dispersion level IR radiation on particles of smaller size decreases significantly. This means that optical detectors are only effective at detecting fires previously identified as slow burning. On the other hand, there is a whole class of materials, for example, rubber and bituminous materials, which when burned produce black smoke, the particles of which also have significantly less scattering properties than white smoke, and the detection of such sources by optical smoke detectors will have a significantly higher equivalent optical density compared to white smoke.

The principle of operation of point optical smoke detectors determines the high probability of false alarms in the presence of dust, steam, aerosols, etc. in the protected area. This circumstance significantly limits the scope of application of smoke detectors, and, despite the possibility of alternative options for selecting detectors, due to the lack of recommendations They are being replaced with cheaper heat detectors, which significantly reduce the level of fire protection for people and equipment. For the same reasons, heat detectors are widely used in explosive areas, although in an explosive environment the heat detector is unlikely to have time to operate before the explosion from the source of the fire.

Heat detectors according to the logic of operation, they can be divided into two types: maximum, which go into “fire” mode when the detector sensor heats up to a fixed temperature, and differential, which go into fire if the temperature rises at a rate above a certain value. Typically, heat detectors use a combination differential and maximum channels, which determines their name as maximum-differential heat detectors. This combination allows fire detection at low temperatures, where the differential channel will give an alarm earlier than the fixed temperature channel. On the other hand, it is obvious that a differential heat detector does not detect a fire with a sufficiently slow temperature rise, in which case only a fixed temperature alarm provides fire detection.

In most fires, thermal detection is not as fast as smoke detection, since early stage fires typically have less of a temperature increase compared to later stages. However, severe environments where aerosols, dust, smoke or even extreme temperatures are present preclude the use of smoke detectors for fire detection. In these areas, a heat detector may provide an acceptable, although significantly less sensitive, alternative. Heat detectors are also used where the risk of fire or the consequences of a fire is considered low, as heat detectors are generally less expensive than smoke detectors.

Detectors flame able to detect flicker infrared radiation emitted by the flame in a controlled frequency range. This, combined with the use of a narrow optical bandwidth, makes the detector immune to interference sources IR range. These detectors are quite expensive compared to smoke detectors. They do not detect smoldering fires, and they detect flames only in direct visibility, which determines limitations in their use. On the other hand, they are practically indispensable for the protection of open areas and high premises; thanks to their high sensitivity, their range reaches 50 m, and with a wide radiation pattern they can protect large areas.

Detectors gas CO(carbon monoxide) work on the principle of oxidizing the gas carbon monoxide to carbon dioxide. This chemical reaction involves several steps that occur on the catalytic surfaces in the CO sensor. The reaction requires an exchange of electrons, which creates a small electricity inside the sensor. The gas entry into the sensor is limited so that all carbon monoxide on the surface of the catalyst is constantly oxidized. This means that the rate of transport of carbon monoxide on the catalytic surface is determined by the concentration gradient between them and the external environment. As a result, the sensor output is a function of the concentration of the surrounding atmosphere, rather than the concentration of the gas moving past the detector.

Carbon monoxide can be used to detect most types of hydrocarbon fires, but its greatest advantage is in detecting slow-moving smoldering fires where the convection current lifting the resulting smoke toward the detector is extremely weak. Under these conditions, normal smoke detection will occur when the concentration of poisonous carbon monoxide is dangerous to humans. Due to the high mobility of gas molecules, carbon monoxide does not require a stream of heated air to rise to the detectors. The distribution of carbon monoxide in a room occurs due to Brownian motion of particles.

Carbon monoxide detectors are resistant to false alarms and are effective at detecting most hydrocarbon occurrences. But they are not applicable in areas where the main hazard is electrical fire. Although fires involving electrical equipment produce carbon monoxide, the formation of visible products during the combustion process makes the choice of optical smoke detectors or highly sensitive smoke detectors more optimal. Also in the category of areas that do not allow the use of CO gas detectors are areas where batteries are charged, as this leads to the formation of a high concentration of hydrogen, which can lead to false alarms.

In areas where the primary hazard comes from flammable chemicals, especially liquid fuels, fires typically involve high temperatures with a strong smoke plume and moderate levels of carbon monoxide. To protect against such fires, it is better to use smoke detectors or, if the environment is unsuitable for the operation of smoke detectors, then use heat detectors. It is intended that the CO detector will not be used in environments where sufficiently high concentrations of hydrogen or hydrocarbon vapor are present. Where there is likely to be long term exposure or high level chemical exposure, it is recommended that CO detectors be tested for proper operation prior to installation.

Spot

Detector that responds to fire factors in a compact area.

Multipoint
Thermal multipoint detectors- these are automatic detectors, sensitive elements which are a collection of point sensors discretely located along the line. The step of their installation is determined by the requirements of regulatory documents and technical characteristics specified in the technical documentation for a specific product.

Linear (thermal cable)

There are several types of linear thermal fire detectors, structurally different from each other:

• semiconductor - linear thermal fire detector, which uses a coating of wires with a substance having a negative temperature coefficient as a temperature sensor. This type of thermal cable only works in conjunction with an electronic control unit. When any section of the thermal cable is exposed to temperature, the resistance at the point of influence changes. Using the control unit, you can set different temperature response thresholds;
• mechanical - a sealed metal tube filled with gas is used as a temperature sensor for this detector, as well as a pressure sensor connected to an electronic control unit. When any part of the sensor tube is exposed to temperature, the internal gas pressure changes, the value of which is recorded by the electronic unit. This type of linear thermal fire detector is reusable. The length of the working part of the metal tube of the sensor is limited in length to 300 meters;
• electromechanical - linear thermal fire detector, which uses a heat-sensitive material applied to two mechanically stressed wires (twisted pair) as a temperature sensor. Under the influence of temperature, the heat-sensitive layer softens and the two conductors are short-circuited.

Smoke detectors

Smoke detectors are detectors that react to combustion products that can affect the absorption or scattering ability of radiation in the infrared, ultraviolet or visible ranges of the spectrum. Smoke detectors can be point, linear, aspirating and autonomous.

Application

The symptom that smoke detectors respond to is smoke. The most common type of detector. When protecting administrative premises with a fire alarm system, it is necessary to use only smoke detectors. The use of other types of detectors in administrative and utility premises is prohibited. The number of detectors protecting the room depends on the size of the room, the type of detector, the presence of systems (fire extinguishing, smoke removal, equipment blocking) that are controlled by the fire alarm system. Up to 70% of fires arise from thermal microfoci developing in conditions with insufficient access to oxygen. This development of the fire, accompanied by the release of combustion products and occurring over several hours, is typical for cellulose-containing materials. It is most effective to detect such fires by registering combustion products in small concentrations. Smoke or gas detectors can do this.

Optical

Smoke detectors that use optical detection react differently to different colors of smoke. Manufacturers currently provide limited information about smoke detector response in technical specifications. Detector response information includes only the nominal response (sensitivity) values ​​for gray smoke, not black smoke. Often a range of sensitivity is given instead of an exact value.

Spot

Triggered smoke detector (red LED lights up continuously).

Smoke detectors must be closed during repairs in the room to prevent dust from entering. A point detector responds to fire factors in a compact area. The operating principle of point optical detectors is based on the scattering of infrared radiation by gray smoke. They respond well to gray smoke released during smoldering in the early stages of a fire. Reacts poorly to black smoke, which absorbs infrared radiation. For periodic maintenance of detectors, a detachable connection is required, the so-called “socket” with four contacts, to which the smoke detector is connected. To control the disconnection of the sensor from the loop, there are two negative contacts, which close when the detector is installed in a socket. Smoke chamber and electronics of a point smoke detector. All IP 212-XX point smoke optical fire detectors according to the NPB 76-98 classification use the effect of diffuse scattering of LED radiation on smoke particles. The LED is positioned in such a way as to prevent direct contact of its radiation with the photodiode. When smoke particles appear, part of the radiation is reflected from them and hits the photodiode. To protect from external light, an optocoupler - LED and photodiode are placed in a smoke chamber made of black plastic.

Experimental studies have shown that the time to detect a test fire when smoke detectors are located at a distance of 0.3 m from the ceiling increases by 2..5 times. And when installing a detector at a distance of 1 m from the ceiling, it is possible to predict an increase in the time of fire detection by 10..15 times.

Linear

Linear- a two-component detector consisting of a receiver block and an emitter block (or one receiver-emitter and reflector block) reacts to the appearance of smoke between the receiver and emitter blocks.

The design of linear smoke fire detectors is based on the principle of weakening the electromagnetic flux between a spatially separated radiation source and a photodetector under the influence of smoke particles. A device of this type consists of two blocks, one of which contains a source of optical radiation, and the other a photodetector. Both blocks are located on the same geometric axis in the line of sight.

Aspiration

An aspiration detector uses forced air extraction from the protected volume with monitoring ultrasensitive Laser smoke detectors provide ultra-early detection of a critical situation. Aspirating smoke detectors allow you to protect objects in which it is impossible to directly place a fire detector.

The fire aspiration detector is applicable in archives, museums, warehouses, server and switching rooms of electronic communication centers, control centers, “clean” industrial areas, hospital premises with high-tech diagnostic equipment, television centers and radio broadcasting stations, computer rooms and other premises with expensive equipment. That is, for the most important premises where material assets are stored or where the funds invested in equipment are huge, or where the damage from stopping production or interruption of operation is great, or the lost profit from the loss of information is great. At such facilities, it is extremely important to reliably detect and eliminate the outbreak at the earliest stage of development, at the smoldering stage - long before the appearance of an open fire, or when overheating of individual components of an electronic device occurs. At the same time, taking into account that such zones are usually equipped with a temperature and humidity control system, and air is filtered in them, it is possible to significantly increase the sensitivity of the fire detector, while avoiding false alarms. Disadvantage aspiration detectors is their high cost.

Autonomous

Autonomous - a fire detector that responds to a certain level of concentration of aerosol combustion products (pyrolysis) of substances and materials and, possibly, other fire factors, in the housing of which an autonomous power source and all components necessary for detecting a fire and directly notifying about it are structurally combined. The autonomous detector is also a point detector.

Ionization

The principle of operation of ionization detectors is based on recording changes in the ionization current that arise as a result of exposure to combustion products. Ionization detectors are divided into radioisotope and electrical induction.

Radioisotope

A radioisotope detector is a smoke fire detector that is triggered due to the effect of combustion products on the ionization current of the internal working chamber of the detector. The operating principle of a radioisotope detector is based on the ionization of the air in the chamber when it is irradiated with a radioactive substance. When oppositely charged electrodes are introduced into such a chamber, an ionization current occurs. Charged particles “stick” to heavier smoke particles, reducing their mobility - the ionization current decreases. Its decrease to a certain value is perceived by the detector as an “alarm” signal. Such a detector is effective in smoke of any nature. However, along with the advantages described above, radioisotope detectors have a significant drawback that should not be forgotten. We are talking about the use of a radioactive radiation source in the design of detectors. In this regard, problems arise in observing safety measures during operation, storage and transportation, as well as disposal of detectors after the end of their service life. Effective for detecting fires accompanied by the appearance of so-called “black” types of smoke, characterized by a high level of light absorption.

High sensitivity allows the use of radioisotope detectors as an integral component of aspiration detectors. When air from the protected premises is pumped through the detector, it can provide a signal when even an insignificant amount of smoke appears - from 0.1 mg/m³. In this case, the length of the air intake tubes is practically unlimited. For example, it almost always registers the fact of ignition of a match head at the entrance of an air intake tube 100 m long.

Electroinduction

Operating principle of the detector: aerosol particles are sucked from the environment into a cylindrical tube (flue) using a small-sized electric pump and enter the charging chamber. Here, under the influence of a unipolar corona discharge, the particles acquire a volumetric electric charge and, moving further along the gas duct, enter the measuring chamber, where an electrical signal is generated on its measuring electrode, proportional to the volumetric charge of the particles and, consequently, their concentration. The signal from the measuring chamber enters the pre-amplifier and then into the signal processing and comparison unit. The sensor selects the signal by speed, amplitude and duration and provides information when specified thresholds are exceeded in the form of closing a contact relay.

Electrical induction detectors are used in the fire alarm systems of the Zarya and Pirs modules of the ISS.

Detectors flame

Flame detector - a detector that responds to electromagnetic radiation from a flame or smoldering hearth.

Flame detectors are used, as a rule, to protect areas where high detection efficiency is required, since fire detection by flame detectors occurs in the initial phase of a fire, when the temperature in the room is still far from the values ​​at which thermal fire detectors are triggered. Flame detectors provide the ability to protect areas with significant heat exchange and open areas where the use of heat and smoke detectors is not possible. Flame detectors are used to monitor the presence of overheated surfaces of units during accidents, for example, to detect a fire in the car interior, under the skin of the unit, to monitor the presence of solid fragments of overheated fuel on the conveyor.

Gas detectors

Gas detector - a detector that responds to gases released during smoldering or burning of materials. Gas detectors can react to carbon monoxide (carbon dioxide or carbon monoxide), hydrocarbon compounds.

Flow-through fire detectors

Flow fire detectors are used to detect fire factors as a result of analyzing the environment spreading through ventilation ducts exhaust ventilation. Detectors should be installed in accordance with the operating instructions for these detectors and the manufacturer’s recommendations, agreed upon with authorized organizations (those with permission for the type of activity).

Manual call points

Fire manual call point - device, intended for manual activation of the fire alarm signal in fire alarm and fire extinguishing systems. Manual fire call points should be installed at a height of 1.5 m from the ground or floor level. The illumination at the installation site of the manual fire call point must be at least 50 Lux. Manual fire call points must be installed on escape routes in places accessible for their activation in the event of a fire. In above ground storage facilities flammable and flammable liquids

Smoke optical-electronic point fire detector.

According to statistics, approximately 90% of fires begin with smoldering materials, which is why smoke detectors (FS) in most cases are the most effective means fire protection. Smoke fire detectors detect a fire hazardous situation at an early stage, with minimal smoke in the upper part of the room, and provide real protection of human life and property. According to European requirements, all premises are protected by smoke detectors, with the exception of areas with the possible appearance of smoke or steam under normal conditions. This situation has ensured in Europe and America a reduction in the number of fires and human casualties by approximately 10 times compared to Russia. The effectiveness of a smoke detector depends on many factors, of course, on the electronics, but its potential characteristics are largely determined by the design of the detector, the shape of the smoke chamber, optocoupler parameters, shielding efficiency, etc.

Operating principle of a smoke optical-electronic fire detector

Smoke optical-electronic fire detectors use the effect of scattering of LED radiation on smoke particles. A similar effect occurs when a searchlight beam passes through a cloud: in a clean environment the beam is not visible, but in the cloud it is scattered on moisture particles, part of the radiation is reflected towards the observer and the structure of the beam becomes clearly visible. The LED and photodiode are located at a certain angle, and the partition prevents direct contact of LED signals with the photodiode (Fig. 1 a). When smoke particles appear, part of the radiation is reflected from them and hits the photodiode (Fig. 1 b).

Rice. 1. Operating principle of an optical-electronic smoke detector

In order for this model to be implemented as a smoke detector, it is necessary complex design, which ensures its stable operation in real conditions. To protect from external light, an optocoupler - LED and photodiode are placed in the smoke chamber. The principle of operation of an optical-electronic PI determines the strong influence on its sensitivity and noise immunity of the shape of the smoke chamber, its color, surface structure, radiation patterns of the LED and photodiode, and their relative location in space.

To ensure effective fire protection signals about a fire hazard should be generated at a relatively low smoke concentration. The sensitivity of a smoke detector is the specific optical density of the medium, measured in dB/m or %/m, at which the FIRE signal is generated. The lower the level of optical density of the medium causes its activation, the higher the sensitivity. According to NPB 65-97, the sensitivity of a fire threshold smoke detector (IP) should be set in the range of 0.05-0.2 dB/m, and its value should be given in the technical documentation for the fire detector. According to Western experimental estimates, with a specific optical density of smoke of 0.2 dB/m, visibility is approximately 50 meters, at 0.5 dB/m - approximately 20 meters, at 1 dB/m - approximately 10 meters, at 2 dB/m - approximately 5 meters. It should be taken into account that initially the smoke layer is located in the upper part of the room.

When tested according to NPB 65-97, the sensitivity of smoke fire detectors must remain within the range of 0.05 - 0.2 dB/m, while the ratio of the maximum optical density to the minimum should not exceed:

• when changing orientation to the direction of air flow - 1.6 times;
• when changing speed air flow 0.625 – 1.6 times;
• from instance to instance - 1.3 times;
• when the supply voltage changes - 1.6 times;
• when the ambient temperature changes to +550C - 1.6 times,
• after exposure high humidity– 1.6 times.

However, simultaneous exposure to several factors, which usually happens in practice, can cause a change in sensitivity optical-electronic IP in a wide range. In addition, during operation, sensitivity decreases due to the accumulation of dust, aging of electronic components, etc. It is also necessary to provide protection from artificial or natural lighting with a brightness of up to 12,000 lux, protection from moisture, dust, corrosion, insects, electromagnetic radiation, mechanical influences, etc.

Absence of corrosion resistance tests in the detector testing program during certification of fire tests according to GOST 50898-96, low impact requirements electromagnetic field etc., allow you to certify detectors that are completely non-responsive modern conditions operation. The high probability of false alarms led in 2003 to the appearance in NPB 88-2001* clause 13.1* of a requirement to form any team when at least two fire detectors are triggered. For the same reason, some manufacturers of control panels have introduced an automatic reset mode for the first fire message, which leads to the loss of precious time and only complicates the procedure for identifying a faulty detector.

In NPB 57-97 “Instruments and equipment of automatic fire extinguishing installations and fire alarm. Noise immunity and noise emission. General technical requirements. Test Methods" provides requirements for noise immunity when exposed to an electromagnetic field (Table 1). Even to control the AUP according to NPB 88-2001* clause 12.11, fire detectors must be resistant to the effects of electromagnetic fields with a degree of severity not lower than second.

The frequency range and electromagnetic field strength levels when tested according to NPB 57-97 do not take into account the presence of several cellular communication systems with a huge number of base stations and mobile phones, nor an increase in the power and number of radio and television stations, etc. Moreover, the “effectiveness” of interference on a fire detector increases with increasing frequency.

According to European standards, a fire detector must withstand exposure to an electromagnetic field of 10 V/m in the ranges of 0.03 - 1000 MHz and 1 - 2 GHz, and 30 V/m in the cellular ranges of 415 - 466 MHz and 890 - 960 MHz. European requirements correspond to modern operating conditions and are several times higher than the requirements for even the highest 4th degree of rigidity according to NPB 57-97. In addition, moisture tests are mandatory, first at a constant temperature of +40°C and a relative humidity of 93% for 4 days, then with a cyclic temperature change of 12 hours at +25°C and 12 hours at +55°C with a relative humidity of at least 93% for another 4 days, corrosion tests when exposed to SO2 gas for 21 days, etc. It becomes clear why, according to European requirements, the signal from two PIs is used only to turn on fire extinguishing in automatic mode.

Smoke spread indoors

Smoke with heated air from a smoldering hearth rises up to the ceiling and spreads in the upper part of the room in a horizontal plane from the hearth (Fig. 2). Moreover, a layer remains directly next to the ceiling clean air. Having reached a vertical barrier, the horizontal flow turns around and the layer of smoke in the upper part of the room increases. Thus, the greatest operating efficiency of fire detectors is ensured when installed horizontally on the ceiling in the center of the room, or vertically on the wall at a distance of 0.1 - 0.3 m from the ceiling. The corners of the room are practically not ventilated; therefore, it is not allowed to install detectors on the ceiling closer than 0.5 m to the wall and on the wall closer than 0.1 m to the ceiling (Fig. 2).

Rice. 2. Spread of smoke from a smoldering fire in the room

This model of smoke propagation is valid for horizontal ceilings, when the height difference in the room does not exceed 600 mm when using a smoke IP, or 150 mm when using a thermal IP. With increasing distance from the source in the horizontal projection, the smoke dissipates, i.e. its specific optical density decreases, therefore the maximum distance between smoke fire detectors is regulated. Thus, it is believed that a standard smoke IP protects a maximum area of ​​176 m2 in the form of a circle with a radius of 7.5 m. The advantage of this formulation of the controlled zone is its applicability to rooms of any shape from the simplest rectangular with flat walls to arbitrary ones with curved walls, round, ellipsoidal , which are becoming increasingly common nowadays.

In NPB 88-2001* “Fire extinguishing and alarm installations. Design Norms and Rules" specifies the only way to arrange smoke PIs - in the nodes of a square grid with the maximum allowable pitch and distance to the wall, which is applicable only for rectangular rooms. These requirements determine the maximum radius of the protected zone, as half the diagonal of the square in the corners of which the detectors are located (Fig. 3). For example, for a room with a height of up to 3.5 m, the maximum pitch of a square grille is 9 m, the diagonal of the square is 12.7, and the radius of the protected zone is ~ 6.36 m. Accordingly, the maximum area in the form of a circle protected by smoke IP according to NPB 88-2001 *, equal to 125 m2.

Rice. 3. Maximum area protected by a smoke detector according to NPB 88-2001*

Formation horizontal chimney

Based on the directions of smoke propagation in the room, the design of a point smoke detector is designed for horizontal air flows. Aerodynamic characteristics of the smoke chamber, design of the smoke inlet IP, protective structural elements, etc. must ensure a sufficiently rapid flow of smoke into the sensitive area of ​​the smoke chamber. Those. For an adequate reaction, the smoke concentration in the smoke chamber should not differ significantly from the smoke concentration in the environment. Moreover, the higher the IP class, the more carefully the design of the IP housing, the shape of the smoke chamber and the radiation patterns of the light and photodiode of the optocoupler should be worked out. Increased requirements for stability of sensitivity are imposed on smoke PIs with several thresholds. When setting the minimum or maximum level, their sensitivity should not exceed acceptable limits. An addressable analogue smoke detector must transmit in real time to the addressable analogue device the current optical density value with high accuracy, starting from minimal smoke concentrations. Therefore, the design of an addressable analogue MT should ensure almost complete absence of dependence of measurement results on the direction and speed of air flows. In addition, low inertia must be ensured, i.e. The smoke concentration in the optical chamber should differ slightly from the concentration in the environment.

All modern smoke detectors have horizontally ventilated chambers designed for relatively free passage of air flow in the horizontal direction. In this case, the area of ​​the chimney and its shape are of great importance. Most European fire detectors have common features: the shape of the detector excludes the possibility of air flow flowing around the detector body in the horizontal and vertical planes. As an example, in Fig. Figure 4 shows smoke detectors of the Sensor Systems, addressable-analog series 200+ and non-addressable series ECO1000.

Rice. 4. Formation horizontal chimney

In addition, it is important to ensure the maximum ratio of the flue area to the internal volume of the smoke chamber. good ventilation the smoke chamber determines the low inertia of work. This task is similar to ventilating a room: an open window - ventilation very weak, the rate of air flow from outside is extremely low, an open window - ventilation improves, several open windows - even better. Obviously, the maximum level of ventilation, the maximum speed of air flow in a round room will be if there is only a floor and ceiling, with an almost completely open structure around the perimeter. Likewise, with a smoke detector, the best ventilation of the internal volume is achieved with the largest possible smoke outlet area, i.e. with an open side wall with a height not lower than the profile of the smoke chamber.

Effective protection against insects is of great importance; its absence significantly narrows the scope of application of the smoke detector. Attempts to save on additional structural elements and provide protection in the form of slots directly in the detector body lead to a sharp reduction in the smoke exhaust area and provide only conditional dust protection at the IP4X level. In addition, in such designs, the optical chamber is usually located away from the smoke exhaust in the housing, which further worsens aerodynamic characteristics of the detector. First the smoke fills inner part housing and only then enters the optical chamber. Moreover, a significant part of the air flow can pass inside the housing past the smoke chamber. Effective protection against insects without a significant reduction in the flue area is ensured only when using a metal or plastic mesh with a mesh size of less than 1 x 1 mm. In Fig. Figure 5 shows a close-up of the smoke exhaust of Sensor System fire detectors.

Rice. 5. Protection of the chimney with a mesh

The main design features of the smoke exhaust of System Sensor detectors of any series:

the protruding part of the bottom cover prevents flow around the body from below;

racks for fastening the bottom cover prevent flow around the body in a horizontal plane;

individual elements of the housing structure form a funnel that directs the air flow into the inside of the detector;

the smoke outlet plane is located perpendicular to the horizontal air flow;

the maximum area of ​​the smoke outlet is ensured, its height is equal to the height of the smoke chamber;

the smoke chamber is protected by a metal or plastic mesh, which practically does not reduce the smoke outlet area and provides reliable protection from insects;

The protective mesh is directly adjacent to the smoke chamber, which eliminates the time spent filling the detector body with smoke.

Smoke chamber design

The basis of an optical-electronic smoke detector is an optical camera and an optocoupler. The design of the chamber must simultaneously satisfy a number of conflicting requirements, for example, provide free access for horizontal air flows and exclude the influence of external light, electromagnetic interference, dust, insects, etc. All major manufacturers of fire detectors pay great attention to the development of the optical camera, since it is this that determines the main characteristics of the IP. To solve this complex technical problem, mathematical modeling methods and experimental studies are used. Moreover, the design of the smoke chamber, the radiation patterns of the LED and photodiode, as well as their location are simultaneously optimized. Therefore, “borrowing” the designs of optical cameras from leading manufacturers, using standard light and photodiodes, with wide diagrams and unadjusted optical axes does not give satisfactory results. In addition, an insufficiently high level of design development leads to the “appearance” of foreign elements in the smoke chamber, for example, electrolytic capacitors that could not be placed elsewhere, and the use of low-quality plastic causes deformation of the original shape of the chamber, which ultimately determines the actual characteristics no higher than when using simpler designs.

The ratio of the photodiode signal level, at which the detector is activated, to the value of the background signal determines its noise immunity. To increase sensitivity and noise immunity in the absence of smoke, a minimum signal level must be supplied to the photodiode. For this purpose, the camera is made of black plastic with a matte surface. The design of the smoke chamber must also simultaneously provide free passage of air and significant attenuation of radiation from external sources Sveta. The requirements are contradictory and their simultaneous fulfillment is only possible when using sufficiently complex structures. In addition, the inevitable accumulation of dust, usually gray in color, on the walls of the smoke chamber leads to an increase in the photodiode signal, which over time causes false alarms. The LED radiation is reflected from the dusty walls of the optical chamber in the same way as from smoke particles. This effect determines the need for periodic maintenance of optical-electronic smoke detectors, which consists of disassembling the detector and cleaning its smoke chamber.

Examples of horizontally ventilated smoke chambers

Modern smoke detectors typically use side-vented, horizontally ventilated smoke chambers that are matched to horizontal air flows (Figure 7). To protect from light, a periodic structure of vertical plates of a certain shape is usually located around the perimeter of the smoke chamber, which prevents direct light from reaching the photodiode.

Rice. 7. Examples of smoke chamber designs

Let's look at examples of designs for horizontally ventilated smoke chambers. In Fig. 7 a) shows a smoke chamber with protective plates in the form of two flat strips connected at right angles. External light bounces off black surfaces several times and is greatly attenuated before it reaches the inside of the camera. On the other hand, part of the LED radiation falls between the plates, which determines a smaller increase in the background signal when dust appears on the surface of the smoke chamber compared to a solid side wall. To equalize the sensitivity from the direction of the smoke exhaust, the arrangement of the plates is not completely periodic: pairs of plates located along the axis of symmetry are connected to each other.

In the design in Fig. 7 b) to increase protection from external light, the plates have a protrusion directed towards the corner of the adjacent plate. The flat surface of the plate, cut as if in a circle, faces the inside of the smoke chamber, which leads to a more rapid increase in the background signal as dust settles.

In Fig. 7 c), 7 d) show examples of further modification of the shape of the plates of the previous design. The relative size of the outer bar is significantly increased; the shape of the plate resembles the letter “T”. This provides slightly greater protection from light, but at the same time the smoke exhaust area is significantly reduced by reducing the clearance between the plates and reducing their number. In addition, the air flow to enter and exit the smoke chamber must sharply change the direction of movement several times, which determines an additional increase in aerodynamic drag. The radiation patterns of the optocoupler are formed by holes in the structures in front of the light and photodiode, and not by the optical system, which leads to a decrease in the energy potential of the system.

Similar designs are commonly used in single-threshold traditional detectors.

Smoke chamber design analog addressable detector

Careful study of the design of the smoke chamber, using methods of mathematical modeling and full-scale testing, allows, if not completely eliminating, then minimizing the manifestation of negative effects. For example, in Fig. Figure 8 shows the design of the Sensor System camera, which is used in most addressable analogue smoke and combined 2, 3 and 4-channel smoke detectors of the latest generations.

Main characteristics:

• the complex shape of the plates (Fig. 9 a), located around the perimeter of the chamber, provides more high degree protection from external light, compared to plates with flat surfaces;
• the smooth bends of the vertical plates do not provide significant resistance to air flows;
• The pointed edges of the plates face inside the smoke chamber, and most of the LED radiation falls between the plates, which minimizes the level of the background signal;
• The corrugated surfaces of the chamber bottom and lid reduce, compared to flat surfaces, the level of the reflected signal, because only protruding parts are highlighted;
• a significant reduction in the area of ​​the inner surface of the chamber, due to the sharp edges of the plates and the corrugation of the bottom and lid, determines the low level of the background signal and its slight increase when dust accumulates;
• air channels created by elongated plates next to the photodiode and LED almost completely eliminate dependence of sensitivity on the direction of air flow without restricting access from the most sensitive directions;
• Effective shielding of the photodiode and electronic circuit eliminates the influence of electromagnetic interference in accordance with European requirements.

Rice. 8. Optical camera design analog addressable smoke detector

Rice. 9. Fragment of a drawing of a smoke chamber of an analogue addressable detector

A similar design in analog addressable the detector provides high accuracy measuring the optical density of the medium at low levels of smoke and low air speeds. This allows the addressable analogue receiving and control device to analyze the dynamics of the process and generate preliminary signals at the very early stages of the development of a fire hazardous situation.

Design of multi-threshold smoke detectors

The non-addressable PROFI and addressable Leonardo Sensor systems smoke smart detectors implement an integrated approach to design optimization, in which individual structural elements simultaneously perform several functions.

Rice. 10. Design of detectors of the PROFI and LEONARDO series

Rice. 11. Design of the smoke chamber of PROFI and LEONARDO detectors

The detector body has a horizontal smoke outlet, protected from insects by a mesh placed in the lid of the smoke chamber (Fig. 10). The smoke chamber, which is absolutely circular in the horizontal plane, provides equally high sensitivity when smoke comes from any direction (Fig. 11). The complex shape of the plates located along its perimeter simultaneously provides good ventilation and protection from external light. Insignificant aerodynamic drag determines the absence of a decrease in sensitivity at low air flow rates. The optocoupler, located on the “second floor”, just above the smoke exhaust, is protected from dust, which mainly accumulates at the bottom of the smoke chamber lid. The shape of the smoke chamber is optimized with infrared LEDs and photodiodes specially developed for these detector series. A narrow LED pattern with two maximums allows you to create a uniformly high level of illumination in the central part of the smoke chamber, in the ± 100 sector, and reduce the illumination of the side walls of the chamber. The radiation pattern of the photodiode also has a width of approximately ± 100 with the maximum directed towards the central part of the smoke chamber (Fig. 12). This ensures a decrease in the background signal received by the photodiode due to reflection from the chamber walls, and an increase in the signal when smoke appears. Increasing the directivity of the optocoupler with optical elements is equivalent to increasing the signal-to-background ratio. Precise adjustment of the optical axes when installing LED and photodiode crystals determines the stability of the sensitivity of the detectors. The light and photodiode have an SMD design and are installed on the board simultaneously with other electronic components, ensuring precise orientation.

Rice. 12. Directional patterns

Rice. 13. Printed circuit board sealing

When making a smoke chamber, red elastic plastic is added along its perimeter from the side of the printed circuit board into the same shape to ensure the strength of the connection (Fig. 13). This layer, in the form of a double gasket, seals the electronic circuit of the detector and protects it not only from moisture, but also from corrosion. In order not to break the seal in the place where the indicators are installed (red and green LED crystals), the signals are transmitted through a light guide installed in the smoke chamber housing.

The round contact pads (Fig. 14) are clearly visible on the printed circuit board, which are used to connect needle contacts during computer testing. During the testing process, the elements, static and dynamic characteristics of the device are monitored. The number of test points on the printed circuit board determines the depth of testing of the detector during the manufacturing process.

Rice. 14. Detector electronics

Much attention is paid to protection from electromagnetic influence. The high degree of integration and miniaturization made it possible to make almost all electrical connections in one layer of the printed circuit board and use a second layer for shielding. The photodiode is also shielded (Fig. 14), and the SMD design made it possible to reduce the length of its leads to a minimum. Without shielding the input circuits of the signal amplifier and the LED outputs, in modern conditions it is impossible to get rid of interference from external electromagnetic interference and avoid false alarms without roughening the sensitivity of the detector. The lack of shielding in detectors determines the presence of false alarms in real conditions. Moreover, the absence of false alarms in a detector without shielding most likely indicates an unacceptably low level of sensitivity. Even in an ordinary office or residential building, a significant level of electromagnetic interference can occur from cellular communications, office radiotelephones, from turning on and off various power plants, from the operation of mobile communications equipment of various services, etc. In this case, it is possible both direct detection of electromagnetic signals on the input circuits of the photodiode signal amplifier, as well as interference to other electrical circuits of the detector and to alarm loops. Slight dusting of the smoke chamber or a shift in the response threshold leads to an increase in the likelihood of a “false fire”. The presence of false alarms should be classified as a malfunction of the fire alarm system, almost on par with a decrease in sensitivity or a failure of the detector.

The use of an effective smoke chamber design, stabilization and sensitivity control provide in detectors of the LEONARDO and PROFI series the ability to adjust the factory sensitivity level of 0.12 dB/m, by 0.08 dB/m, or by 0.16 dB/m, depending on the type of object . At the same time, the sensitivity does not change in the operating temperature range from -30°C to +70°C and when dust accumulates for several years. There are no false alarms even at the highest sensitivity level in complex electromagnetic environments.

Linear optical-electronic smoke detectors.

Linear smoke detectors are widely used in systems fire safety. They are indispensable in rooms with high ceilings and large areas; they have maximum sensitivity for black smoke. There is an earlier detection of fire by a linear detector compared to point smoke detectors in real conditions.

There are several types of linear smoke detectors. The most common two-component linear PIs consist of a transmitter and a receiver, which are located on opposite sides of the protected area. The receiver receives the transmitter signal and compares its level with a value corresponding to a clean environment. The appearance of smoke between the receiver and transmitter causes signal attenuation and leads to the formation of the FIRE signal (Fig. 1).

Figure 1 - Operating principle of an optical-electronic linear smoke detector

Figure 2 - Linear detector 6424

Linear smoke detector provides better detection performance various types fires, compared with point optical-electronic, ionization and heat detectors (Table 1).

Table 1 - Sensitivity of fire detectors to test fires
(O - perfectly detects; X - detects well; N - does not detect)

It should also be noted that all modern linear detectors have several sensitivity thresholds and dust compensation for optics and light filters, which makes it possible to take into account operating conditions, eliminate false alarms and reduce maintenance costs. For point detectors, these functions are implemented only in addressable analog systems and in the most advanced threshold systems, for example in the latest series of Sensor PROFI and Leonardo systems. This is explained by the strict restrictions on weight and size characteristics and power consumption imposed on point-type fire detectors.

Types of linear detectors

Linear smoke detectors can be divided into two large classes: two-component, consisting of separate receiver and transmitter units, and modern single-component ones - one transceiver unit with a passive reflector. The construction of a linear detector determines the requirements for the technical characteristics of the components, their design and placement. For a two-component detector, it is necessary to ensure a stable transmitter signal level over the entire range of operating temperatures and supply voltages, because a decrease in the transmitter signal level leads to the formation of a false FIRE signal. The receiver must ensure that the value of the reference signal level is stored in the receiver's non-volatile memory and that the response threshold is adjusted when the optics become dusty during operation.

In addition, to increase the energy potential, optical systems are used in the receiver and transmitter, providing fairly narrow radiation patterns. This construction determines the complexity of setting up and operating linear detectors. To ensure operability, it is necessary to carry out a rather labor-intensive adjustment, during which the position of the receiver and transmitter is established, corresponding to the reception of the maximum signal. A change in the position of the receiver or transmitter during operation causes a deviation in the directional pattern, a decrease in the signal level and the formation of a false FIRE signal, which is not reset without re-adjusting the detector. After the reset, the signal level reduced due to misalignment is compared with the signal level in a clean optical medium, and a confirmation of the FIRE signal is issued. The situation for the detector is no different from confirming the FIRE signal in the presence of smoke. Accordingly, mounting the receiver and transmitter is allowed only on permanent structures. The shape of the radiation pattern is chosen in such a way that a slight displacement of the supporting structures does not disrupt the operation of the linear detector. During operation, it is usually allowed to shift the maximum of the radiation pattern relative to the optical axis within the order of ±0.5°, which corresponds to a beam shift of ± 87 mm at a distance between the receiver and transmitter of 10 meters, and by ± 870 mm at a distance of 100 meters.

To ensure the operation of two-component detectors at different ranges, it is usually necessary to use several transmitter signal levels and adjust the receiver gain, which creates additional difficulties during setup and adjustment. Another significant drawback is the need to connect both the transmitter and receiver to a power source - this means significant cable consumption, usually exceeding the distance between the receiver and transmitter. In addition, when installed in one room in parallel with several linear detectors It is necessary to prevent signals from neighboring transmitters from reaching the receiver. In this case, some manufacturers recommend installing receivers and transmitters in a staggered pattern, which leads to an additional increase in cable consumption and installation work. Moreover, installation of this part of the loop is usually difficult due to high ceilings, or due to the need for hidden wiring.

Almost all of these disadvantages are absent in single-component linear smoke detectors, in which the receiver and transmitter are located in one block, and on the opposite side there is a passive reflector that does not require power (Fig. 6). It consists of a large number of prisms, the structure of which ensures that the signal is reflected in the direction of the source. A similar design is used in automobile reflectors. Thus, the reflector does not require not only power supply, but also no adjustment. Accordingly, cable consumption and the complexity of installation and adjustment are reduced several times.

Figure 6 - External (top) and internal (bottom) views of the 6500R/6500RS single-component detector and reflector

Moreover, the reflector can be installed on non-permanent and even vibrating structures. The position of the reflector can be changed within ±10°. At large angles, a decrease in the level of the reflected signal occurs due to a decrease in the projection of the reflector onto a plane perpendicular to the optical axis, i.e. by reducing the equivalent reflector area.

Placing the receiver and transmitter in one unit makes it possible to automatically selecting the signal level measurement range during adjustment, automatic adjustment of the transmitter radiation level and receiver gain depending on the range of the controlled area.

In addition, it additionally becomes possible to temporarily select signals, the ability to use one reflector when close location two or three detectors, the ability to compensate for changes in optical density not related to the occurrence of a fire hazardous situation during the day to eliminate false alarms, etc.

Sensitivity control is also greatly simplified one-component linear detector. Instead of using optical filters, signal attenuation can be achieved by blocking an appropriate area of ​​the reflector. For the case of uniform irradiation of the reflector, there is a simple dependence of the signal attenuation on the size of its area. This method is implemented in one-component detector 6500 System Sensor. On its reflector there is a scale from 10% to 65% with a discrete 5%, which determines the amount of signal attenuation when the shading area changes (Fig. 7). Thus, it is possible to accurately measure the sensitivity of the 6500 detector at any of the four thresholds 25%, 30%, 40%, 50%.

Figure 7 - Detector sensitivity test scale

A linear smoke detector protects an area up to 100 - 200 meters long and, accordingly, replaces, depending on the length and height of the room, more than 10 - 20 point smoke detectors. The complexity of installing, testing and maintaining point smoke detectors in the presence of high shelves determines the additional advantages of linear detectors. Moreover, the installation of point detectors in rooms with a height of more than 12 meters is prohibited due to a sharp decrease in their effectiveness: when smoke reaches the ceiling, it spreads over a large area, accordingly its specific density decreases and, accordingly, the time to detect a fire increases. This effect has virtually no effect on the performance of the linear detector, because the decrease in specific optical density is compensated by an increase in the extent of smoke (Fig. 8). The high efficiency of linear detectors in such conditions determined the possibility of protecting premises of considerable height. According to European recommendations, linear detectors can be installed to protect people in rooms up to 25 meters high, and to protect property - up to 40 meters in one tier. In this case, the distance between the optical axes is selected in the range from 9 to 15 meters and there is no need to reduce it when the height of the room increases.

Figure 8 - Smoke distribution in a room with a high ceiling

According to Russian requirements given in NPB 88-2001 * "Fire extinguishing and alarm installations. Design standards and rules"), in rooms up to 12 meters high, the distances between optical axes should not exceed the distances between rows of point smoke detectors at the same height. Those. the difference in physical processes during smoke detection point and linear detector. Moreover, in rooms with a height of 12 to 18 meters, two-tier installation of linear smoke detectors is prescribed. It is required to install an additional tier of linear detectors at a height of 1.5 - 2 meters from the fire load level, but not less than 4 meters from the floor plane. Because The placement of linear detectors in rooms above 18 meters is not provided for by the standards at all; in practice, in some cases, a three-tier installation is used, although an increase in the height of the room can be compensated with a large margin by setting a higher sensitivity. This situation determines in some cases the choice of cheaper and less efficient equipment.

A list of regulatory and technical documentation, the requirements of which must be taken into account when studying this topic.

1. SP 5.13130.2013 Fire protection systems. Fire alarm and fire extinguishing installations are automatic. Design norms and rules.

2. NPB 58-97 Addressable fire alarm systems. General technical requirements.

3. NPB 65-97. Optical-electronic smoke detectors. General technical requirements.

4. RD 78.145-93. Systems and complexes of security, fire and security and fire alarm system. Rules for production and acceptance of work.

5. Manual for RD 78.145-93.

6. NPB 66-97 Autonomous fire detectors. General technical requirements.

7. NPB 70-98 Manual fire detectors. General technical requirements.

8. NPB 71-98 Gas fire detectors. General technical requirements.

9. NPB 72-98 Fire flame detectors. General technical requirements.

10. NPB 76-97 Fire detectors. General technical requirements.

11. NPB 81-99 Radioisotope smoke fire detectors. General technical requirements.

12. NPB 82-99 Optical-electronic linear fire smoke detectors. General technical requirements. Test methods.

13. NPB 85-2000 Thermal fire detectors. Technical requirements fire safety.

14. SP 54.13130.2011 Code of rules. Residential multi-apartment buildings. Section 7. Fire safety.

15. Articles by I.G. Not bad for fire detectors.

16. www. txcom.ru.

17. www.tinko.ru.

18. www.kvarta-kmv.ru.

19. www. signaldoma.ru.

Self-test questions.

1. Classifyfire detectors by type of detection zone.

2. Classifyfire detectors based on the detection principle?

3. Explain the principle of detecting a fire smoke point optical-electronic detector.

4. Explain the detection principle of a fire smoke linear optical-electronic detector.

5. Why is the radioisotope detector not widely used??

3.1.8. Selection of fire detector types

The choice of types of fire detectors is made depending on the purpose of the protected premises and the type of combustible load according to the recommended Appendix 12 of NPB 88:

3.1.9. Placement of manual call points

The installation locations of manual fire call points, depending on the purpose of buildings and premises, are determined in accordance with the recommended Appendix 13 of NPB 88.

3.2. NPB 110 requirements for the selection of objects protection by fire alarm installations

3.2.1. General provisions

NPB 110 establish basic fire safety requirements that regulate the protection of buildings, structures, premises and equipment at all stages of their creation and operation by automatic fire extinguishing installations (AUPT) and automatic fire alarm installations (AUPS)* (*hereinafter referred to as automatic installations).

Objects not related to state and municipal property listed in paragraphs 1, 2, 7 of table 1, paragraphs 1-8 of table 2, paragraphs 1-15, 16.1, 17.1, 19, 20 of table 3, paragraphs 1-8 of table 4 appendices of these standards, it is allowed to equip an automatic fire alarm system without an automatic fire alarm device. At the same time, at these facilities the safety of the people in them must be ensured and the threat of fire and its dangerous factors for other persons must be eliminated, which must be confirmed by appropriate calculations, and the equipment used in the AUPS must meet modern requirements.

Along with these standards, it is necessary to be guided by departmental (industry) and territorial lists, as well as other regulatory documents approved in the prescribed manner.

Departmental (industry), territorial lists, as well as other regulatory documents that determine the need to protect buildings, structures, premises and equipment of AUPT and AUPS, developed in accordance with the requirements of these standards, are not subject to approval (1).

In these standards, a building means a building as a whole or a part of a building (fire compartments), separated by fire walls of type 1.

Under the standard indicator of room area in section III mandatory application of these standards is understood as a part of a building or structure, separated by enclosing structures classified as fire barriers with a fire resistance limit of at least 0.75 hours (partitions EI 45, walls and ceilings REI 45) (2).

Buildings and premises listed in paragraphs 3, 6.1, 7, 9, 10, 13 of Table 1, paragraphs 14-19, 26-29, 32-38 of Table 3, when using automatic fire alarms, should be equipped with smoke fire detectors (3).

In buildings and structures, all rooms, regardless of area, should be protected with appropriate automatic installations, except for rooms (4):

with wet processes (showers, toilets, refrigerated chambers, washing rooms, etc.);

ventilation chambers (supply and exhaust chambers that do not serve industrial premises of categories A or B), water supply pumping rooms, boiler rooms and other premises for the building’s engineering equipment, in which there are no flammable materials;

staircases.

Coordination of projects for automatic fire protection systems for buildings, structures, premises and equipment in the divisions of the State Fire Service is carried out in accordance with regulatory documents on fire safety and instructions for the organization and implementation of state fire supervision (11).

The list of buildings and premises that it is advisable to equip with fire automatics with the transmission of a fire signal via a radio telecommunication system to the central communication center “01” of the State Fire Service is determined by the relevant territorial division of the State Fire Service of the Ministry of Emergency Situations of Russia, based on their technical capabilities (12).

When determining the type of automatic installation (AUPT or AUPS) to protect premises of category VZ according to fire danger the standard indicator (room area) can be increased by 20% (13).

3.2.2. Buildings subject to protection by AUPS

Table 1

** Along with AUPS, apartments and dormitories should be equipped with autonomous optical-electronic smoke detectors in accordance with SNiP 2.08.01.

***AUPS heat fire detectors are installed in the hallways of apartments and are used to fulfill the requirement of clause 1.34* of SNiP 2.08.01-89*.

3.2.3. Structures subject to protection by AUPS

table 2

* In these standards, cable structures mean tunnels, channels, basements, shafts, floors, double floors, galleries, chambers used for laying electrical cables (including in conjunction with other communications).

** 1. Cable structures, spaces behind suspended ceilings and under double floors are not equipped with automatic installations (except for paragraphs 1-3):

a) when laying cables (wires) in steel water and gas pipes or solid steel boxes with openable solid lids;

b) when laying pipelines and air ducts with non-combustible insulation;

c) when laying single cables (wires) of the NG type to power lighting circuits;

d) when laying cables (wires) of the NG type with a total volume of combustible mass of less than 1.5 liters at the control center behind suspended ceilings made of materials of the flammability groups NG and G1.

Good afternoon, Dear Readers!
Today we will discuss the issue of the number of fire detectors that need to be equipped in one small room so that the design solution does not contradict regulatory documents. I will try to present it in accessible Russian language, understandable to the average person.

We are all accustomed to the fact that two fire detectors are installed in a room and that is actually enough, especially since in SP5.13130.2009 (hereinafter I will simply write “SP5”) in clause 13.3.2 it is clearly stated - “In each protected premises, at least two fire detectors should be installed, connected according to the logical “OR” circuit. ” and you can even put just one (according to clause 13.3.3 if the conditions ……….etc. etc. are met - we will return to these conditions later. However, in clause 14.3 of the same SP5 the following is stated - “ 14.3 To generate a control command according to 14.1 in the protected room or protected area there must be at least:
– three fire detectors when they are included in the loops of two-threshold devices or in three independent radial loops of single-threshold devices;
– four fire detectors when they are connected to two loops of single-threshold devices, two detectors in each loop;
– two fire detectors that meet the requirement of 13.3.3 (a, b, c), connected according to the logical “AND” circuit, subject to timely replacement of the faulty detector;
– two fire detectors connected according to the logical “OR” circuit, if the detectors provide increased reliability of the fire signal.”
As we see, in clause 14.3 there is a link to clause 14.1...... what's the matter here? We read and find out that clause 14.1 is prescribed for a fire alarm system that automatically controls warning systems, smoke removal or engineering equipment of the facility......that is, in fact, for any alarm system, since it still turns on something at any facility (for example the same siren) or turns off (for example, ventilation). So what - in one paragraph of SP5 it is written that two or even one is enough, and in another - three pieces at least...... hmm, it’s not clear. Let's try to clarify this question today. I will write how I see it and read the text of the norms, and you, in turn, if you disagree with something, write in the comments and we will discuss the points. So, clause 14.3 position 1 – “ three fire detectors when they are included in the loops of two-threshold devices or in three independent radial loops of single-threshold devices; “. Here we're talking about about conventional heat or smoke fire detectors (analog - not addressable), which are connected to a conventional two- or single-threshold device. Detectors, for example DIP-45 or DIP-41, a device - well, it could be “Signal-20” or “VERS” or “Magister”, that is, the receiving and control device sees and controls the fire alarm loop, which can include both 4 and 10 and 20 fire detectors. In this case, the device records the states “NORMAL”, “FIRE”, “FAULT” and “ATTENTION” (if the device is a two-threshold one), of the entire loop, and not of any specific fire detector. So to make it clear, the first threshold is “ATTENTION”, the second, respectively, “FIRE”. Taking into account the above, three fire detectors are installed in the room - the first one will sound “ATTENTION”, the second one will sound “FIRE”, and the third one will be a spare one. What is the spare one for? The answer is simple - the analog device does not control the performance of each fire detector - it controls only the performance of the entire loop, and if (let's say) the fire detector burns out due to being flooded with water from the upper floors or simply works for a little and stops working quietly and peacefully due to a manufacturing defect, then the receiving control device will not notice this, and if there were only two detectors in the room and one of them stopped working, then the “FIRE” state would never have occurred, even if the whole room burned to black - only one would have worked for “ATTENTION” and that's all. This is why it is necessary to install three detectors. Well, we won’t consider an example about single-threshold devices, since everything is similar, especially since there are practically no such devices left, and in fact we’re just too lazy to write a lot of text. When, hopefully, we have understood the need to install three detectors when using analog detectors and devices, we can move on to the next point.
Now let's look at position 2 of paragraph 14.3 - “ two fire detectors that meet the requirement 13.3.3 (a, b, c), connected according to the “AND” logical circuit, subject to timely replacement of the faulty detector;.”

Let’s first look at what this wonderful logical “AND” circuit is. It’s easy to guess what the “AND” circuit means – one detector has triggered “AND” another detector. Accordingly, in order for the PPK (control receiving device) to go into the “FIRE” state, it is necessary, according to this logical scheme, to trigger two fire detectors, as we are used to - “ATTENTION” - the first and “FIRE” - the second. So what is the difference between the first option we examined, when we install three detectors, from the second option, when we install only two? In order to answer this question, we turn to the condition that is mentioned in paragraph 2 for fire detectors - “satisfying the requirement 13.3.3 (a, b, c)”. Great, so what are these conditions? See clause 13.3.3. We read - point a) - the area corresponds to the plate - well, that’s okay, since one detector, according to plate 13.3-13.6, controls from 55 to 85 square meters depending on the installation height (if you look at the smoke detector) and this is quite a lot, point b) - provides automatic control of the fire detector's performance under the influence of factors external environment, confirming the performance of its functions, and a notification of serviceability (malfunction) is generated on the control panel ; - oppa, and this is already serious - only an addressable control panel can provide control of a fire detector and, accordingly, only an addressable fire detector, since it is the addressable detector that exchanges response messages to request messages with an addressable control panel - analogue detectors do not have such functions. Well, to complete the picture, paragraphs c) – c) identification of a faulty detector is ensured using light indication and
the possibility of replacing him with duty personnel for set time, determined in accordance with Appendix O ; - well, that’s all, the malfunction of this particular fire detector can be identified and reflected only by the address control panel - that is, the control panel will show that this address (fire detector), for example, is dusty or burned out and does not respond to the control panel request at this address - that is run and repair, and you need to do it within the set time specified in Appendix “O”, since while the detector is hanging on the ceiling burnt out, the room remains unprotected, since as we know, there are only two detectors installed there and one of them does not work and there is a spare third no, as in the first variant we analyzed, but for the “FIRE” state you need two of them, that is full set. That is, according to option 2, it is necessary to install addressable fire detectors - no more and no less. Now let's move on to the third option - two fire detectors connected according to the logical “OR” circuit, if the detectors are both
increased reliability of the fire signal is ensured . What does it mean? Let's take a look. Firstly, the word “OR” – what does it mean? The answer is simple - in order for the alarm in the room to go off for “FIRE”, it is necessary that either one or the second of the two installed fire detectors work. That is, it turns out that just one is enough! Interesting option! BUT, again there is a BUT - without this BUT Russian standards don’t work – not everything is as rosy as it seems. Since we understand that the “FIRE” state is activated by one fire detector, we look at what type of detector it should be so that the warning systems, smoke removal systems, etc., are started from it alone. To do this, we go to paragraph 14.2 of our favorite SP5 and read that yes, you can trigger notification types 1,2,3, smoke removal and others engineering systems, that is, “lo and behold,” even turn off the ventilation - and all this from one detector, but the detector in this case must comply with the recommendations (and these read “REQUIREMENTS”) set out in Appendix “P”. This is where exactly that “buried dog” lies - open application “P” and read - just two points:
R.1 Use of equipment that analyzes the physical characteristics of factors
fire and (or) the dynamics of their change and providing information about its technical condition
(for example, dust).
R.2 Use of equipment and its operating modes that exclude impact on detectors
or trails of short-term factors not related to fire.
So what follows from this? Firstly, by analogy with option 2 described above, we understand that detectors again must be addressable in order to provide information about their technical condition, for example dust content. Well, point P2 means that the detectors must be included in the device with the ability to re-query the status. That is, the sensor was triggered, the PPK accepted this alarm, but did not go into the “FIRE” state - the PPK acted wiser - it reset the first sensor trigger to check the reliability of the trigger (or maybe a wind from the street blew into the window and brought a little smoke from the leaves that the wiper burns on the street?) and waits for a second response from this sensor. If it triggered a second time, well, that’s it, it means that something is burning in the room and then the control panel issues a “FIRE” signal, and if it does not trigger again within, for example, 30 seconds (the time is set by the control panel settings), then the first alarm of the detector is forgotten as if it and it wasn’t - the PPK believes that this is a “false”. This is what is written in the standards “Use of equipment and its operating modes...”.
Well, let’s summarize the results of our difficult post. So it turns out like this -

in one small room according to current standards fire safety, it is necessary to install either THREE analog non-addressable fire detectors, connected according to the “AND” circuit, or TWO addressable fire detectors, connected according to the “AND” (“OR”) circuit, depending on the trigger duplication program included in the settings of the addressable control panel.

If you want to copy an article I wrote How many fire detectors should I install? or fragments of the article to paste into some other site, please copy along with links to my page, since the article, after all, is mine intellectual property– I wrote it myself.
Here we actually sum up our topic. I look forward to your comments with objections, if you do not agree with what I wrote, or comments expressing pleasure, agreement and gratitude for the clarifications. Your comments will stimulate my desire to write something else - the post is written for Readers, and not just into the void. I recommend taking a look at my other articles, available via the links:

– how many fire detectors should be installed in a compartment limited by beams of more than 0.4 meters?

– cable penetrations “Stop-fire”

– fire detector on the wall

– smoke removal systems, compensation

– hot work and work with an angle grinder – requirements.

– marking of explosion-proof equipment

Fireproof cable line - what kind of beast is it?

– job description specialist in P.B.

– fines for violations in the field of fire safety

– calculation of sound pressure at the facility

Technical report - what is it for?

Fire protection behind a suspended ceiling

Addressable fire detector - how much per room?

Our group VKontakte –

Fire detector- a device as part of an alarm system for generating a fire signal. In APS systems, they are designed to detect fire factors or various combinations of factors at an early stage.

Notification - a message containing information about controlled changes in the state of a protected object or technical means of an alarm system and transmitted using electromagnetic, electrical, light and (or) sound signals.

An autonomous fire detector is a sensor that responds to a certain level of concentration of aerosol combustion products (pyrolysis) of substances and materials and, possibly, other fire factors. The housing of this model contains an autonomous power source and all the components necessary to detect a fire and immediately notify about it.

What types of fire detectors are there?

• Security and fireman(combining the functions of a security guard and a firefighter).
• Manual fireman(device for generating a fire signal with manually actuation).
• Automatic fireman(automatically responding to factors associated with a fire).
• Autonomous firefighter (a sensor that responds to a certain level of concentration of aerosol combustion products (pyrolysis) of substances and materials and, possibly, other fire factors. The housing of this model contains an autonomous power source and all the components necessary to detect a fire and immediately notify about it).
• Addressed firefighter((API) - technical means APS, which transmits its address code along with a fire notification to the addressable control panel).
• Thermal fireman(responding to a certain temperature value and (or) the rate of its increase).
• Maximum thermal(triggered when a certain ambient temperature value is exceeded).
• Differential thermal(triggered when a certain value of the rate of increase in ambient temperature is exceeded).
• Maximum differential thermal(combining the functions of maximum and differential thermal fire detectors).
• Fire flame detector(responsive to electromagnetic radiation of the flame).
• Smoke fireman(reacting to aerosol combustion products).
• Radioisotope(smoke fire detector, triggered as a result of the influence of combustion products on the ionization current of the detector working chamber).
• Optic(smoke fire detector, triggered as a result of the influence of combustion products on the absorption or scattering of electromagnetic radiation from the detector).
• Combined optical-electronic

Smoke detectors (sensors)

Such models of sensors are installed at most objects. The main purpose of such devices is to detect fires accompanied by the appearance of smoke in an enclosed space. various buildings and structures. The design is designed to be installed on solid foundations and with protection against small insects.

The placement and installation of smoke fire detectors must be carried out in accordance with the design and the requirements of NPB 88-2001*, technological maps and instructions.

Devices of this type are installed on a durable ceiling structure that is not subject to rapid destruction. Installation on walls, beams, columns and suspension on metal cables under the ceilings of buildings with light, aeration, and skylights is also allowed. In these cases, detectors must be placed at a distance of no more than 300 mm from the ceiling (including the overall dimensions of the device). Smoke and heat fire detectors should be installed in each ceiling compartment limited by building structures (beams, purlins, slab ribs, etc.) protruding from the ceiling by 0.4 m or more. If there are protruding parts on the ceiling from 0.08 to 0.4 m, the area controlled by the detector is reduced by 25%. If there are boxes on the ceiling in a controlled room, technological platforms with a width of 0.75 m or more, having a solid structure and spaced at a lower level from the ceiling at a distance of more than 0.4 m, it is necessary to additionally install fire points under them.

Detectors (sensors) detecting temperature changes

This type of equipment is installed at all facilities where the use of smoke models is prohibited. Designed to detect fires accompanied by the release of a certain amount of heat in enclosed spaces of various buildings and structures. Structurally, the sensor is designed to be installed on solid foundations.

The placement and installation of thermal fire detectors must be carried out in accordance with the design, the requirements of NPB 88-2001*, technological maps and instructions.

Thermal fire detectors should usually be installed on the ceiling. If it is impossible to install detectors on the ceiling, they can be installed on walls, beams, columns. It is also allowed to hang detectors on cables under the ceilings of buildings with light, aeration, and skylights. In these cases, detectors must be placed at a distance of no more than 300 mm from the ceiling (including the overall dimensions of the detector). Smoke and heat fire detectors should be installed in each ceiling compartment limited by building structures (beams, purlins, slab ribs, etc.) protruding from the ceiling by 0.4 m or more. If there are protruding parts on the ceiling from 0.08 to 0.4 m, the area controlled by the detector is reduced by 25%. If there are boxes or technological platforms on the ceiling in a controlled room that are 0.75 m wide or more, have a solid structure and are spaced at a distance of more than 0.4 m at the bottom mark from the ceiling, it is necessary to additionally install fire detectors underneath them.

Detectors (sensors) of forced manual start

Manual fire detectors (IFR) are part of any automatic fire extinguishing and fire alarm installation and are designed to work with alarm and trigger devices, fire-fighting and fire-security control devices

The purpose of the IPR determines the requirements for their placement. According to NPB 88-2001* “Fire extinguishing and alarm installations, design standards and rules,” manual fire call points should be installed on walls and structures at a height of 1.5 m from the ground or floor, at a distance of no more than 50 m from each other inside buildings and not more than 150 m outside buildings. At the same time, at a distance of at least 0.75 m from the manual call point there should be no various controls or objects that impede access. Even in the hallways of apartments, it is not allowed to “improve the interior” by installing IPR in closets, where they will be difficult to find even in the absence of a fire. The illumination at the installation site of the manual fire call point must be at least 50 lux.

In accordance with Appendix 13 to NPB 88-2001 * in industrial buildings, structures and premises (workshops, warehouses, etc.) it is recommended to install IPR along evacuation routes, in corridors, at exits from workshops, warehouses and on landings of each floor . In administrative and public buildings - in corridors, halls, lobbies, on staircases, at building exits. In cable structures (tunnels, floors, etc.) - at the entrance to the tunnel, to the floor, at emergency exits from the tunnel, at the branching of tunnels.

What to look for when choosing a fire detector:

• Power consumption
• Weather resistance
• Response to external factors (light, air flow from heating elements)
• Possibility to fine-tune sensor sensitivity
• Addressability or analogue design

What are the special detectors in the fire system:

• Detectors transmitting several alarm levels
• Explosion-proof version
• Autonomous fire detectors
• Special designs for specific needs

How to choose the right model

The selection of fire alarms and the elements that make them up must be carried out by design organizations. Let’s try to tell you in a nutshell what different models of this equipment react to.

Smoke or smoke in the room. Each fire sensor monitors a certain volume of the room, analyzing the presence of combustion products in the air entering its chamber. There are two main types that work according to this principle: point and linear control. In the first case, combustion products, when entering the optical chamber of the sensor, do not produce infrared ray get from the transmitter to the receiver. Moreover, each model has different levels of response. In the second case, the (linear) beam passes along a line through a certain volume of the room and is reflected into special reflectors. If the beam does not come back, it means that it is interfered with by the presence of smoke in the air.

Heat or open flame. In this case, the detectors evaluate the value and increase in temperature in the protection room. Everything here is much simpler, since this type of sensors has been used for a very long time. The capsule inside reacts to a certain temperature and gives notification of a critical temperature increase. Detectors open flame react in a slightly different format. An open fire emits optical radiation, which has its own characteristics in different areas of the spectrum.