Automatic fire alarm installations abstract. Sending a signal about a fire using an alarm system. General provisions when choosing types of fire detectors for a protected object

Automatic fire detection and extinguishing systems include:

• automatic settings fire alarm (AUPS) designed to detect a fire in its initial stage, report on the place of its occurrence, give an appropriate signal to the security post (duty post);
• automatic fire extinguishing installations (LUP), designed to automatically detect and extinguish a fire in its initial stage with the simultaneous filing of a fire alarm.

The current practice of designing LUP and AUPS is such that APs simultaneously perform the functions of AUPS. AUP and AUPS systems protect buildings, premises in which flammable and combustible substances are stored or used, valuable equipment and raw materials, warehouses for petroleum products, varnishes, paints, book depositories, museums, rooms with electronic computers, etc.

The sensors that respond to fire factors (fire, smoke, gas, elevated air temperature, increased rate of rise of any factor, etc.) in the AUP and AUPS systems are fire detectors (PI), which are installed in the premises to be protected. In the event of a fire, they send a signal to the fire control panel, control devices, as well as to the fire department station (or to the duty personnel station), where they inform about the situation that has arisen, indicating the room, zone where the fire extinguisher has worked.

When two or more PIs are triggered simultaneously (and they are usually placed in each room at least two), control devices, depending on the program embedded in them: turn on the warning system and control the evacuation of people in case of fire, turn off the power supply technological equipment, turn on smoke exhaust systems, close the doors of the room where the fire that has arisen is supposed to be extinguished with gas fired extinguishing agents, and at the same time delay the release of fire extinguishers for the time during which people must leave the corresponding room; if necessary, turn off ventilation; in the event of a power failure, the system is transferred to a backup power source, a command is given to release the fire extinguishing agent into the combustion zone, etc.

The choice of one or another type of PI depends on the predominant type of emerging fire factors (smoke, flame, etc.). For example, in accordance with "SP 5.13130.2009. Fire protection systems. Automatic fire alarm and fire extinguishing installations. Design norms and rules", approved by order of the Ministry of Emergency Situations of Russia dated March 25, 2009 No. 175, industrial buildings with the presence of wood, synthetic resins or fibers polymer materials, textile, rubber products, protect PI by smoke, heat, flame; rooms with computers, radio equipment, administrative and public buildings - smoke PI, etc.

On fig. 34.1 shows one of the schemes for automatic detection and extinguishing of a fire. In the event of a fire in one of the premises, after the operation of two or more fire alarm sensors 2, the signal from them is fed to the control panel 1. This device sends a signal to the fire department (to the fire department), turns on the light alarms 14 "Fire" located outside and inside the building, and the pump 6 water fire extinguishing or undermines squibs 8 start-up of the gas fire extinguishing system. In addition, the AWP program can provide for the simultaneous de-energization of process equipment through a disconnecting unit 10, turning on light alarms 12 "Do not enter", installed outside the building, and light annunciators 13 "Go away" installed indoors.

In some cases, the program may also delay the release of gas until all doors are completely closed, when a high fire extinguishing concentration is needed. At the same time, the doors close automatically, and their position is controlled by sensors. 4. If necessary, the fire alarm and extinguishing system can be turned on manually by pressing one of the buttons 3. In the event of a malfunction in the automation system, a corresponding signal is sent to the fire department post. When the automatic mode is turned off, the alarms light up 11 "Automatic disabled", located in the protected area.

All automatic fire extinguishing installations can be operated manually and automatically. In addition, they simultaneously perform the functions of an automatic fire alarm.

Automatic fire extinguishing installations are divided into design for: sprinkler, deluge, sprinkler-drencher, modular; according to the type of fire extinguishing agent used - for water (including with water mist, drops - up to 100 microns), foam (including with high-expansion foam), gas (using carbon dioxide, nitrogen, argon, various refrigerants, etc.) , powder (modular), aerosol, combined fire extinguishing.

On fig. 34.2 as an example, a diagram of a sprinkler fire installation is presented. It consists of an extensive system of pipes 7 located under the ceiling and filled with water under pressure created by an automatic (auxiliary) water feeder. 4. Sprinklers (sprinklers) are screwed into the pipes every 3–4 m 8, the outlets of which are closed with glass or metal fusible locks. When a fire occurs and the air temperature in the room reaches a certain value (for various sprinklers it is 57, 68, 72, 74 and up to 343 ° C (16 steps in total)) the locks are destroyed and water, sprayed, enters the combustion zone. The nominal operating temperature of sprinklers is usually higher than the maximum permissible operating temperature in the room by about 1.5–1.14 times. Also used sprinkler AUP with forced start. At the same time, the control and signal valve 5 is activated, the main water feeder is turned on. 2 (pump) that draws water from a water source 1 (main tank or fire water main) and a fire alarm sounds.

Rice. 34.1.

СО1, СО2, СО3, СО1 - loops of light annunciators; 30 - sound alert loop; ШС1, ШС2, ШС3 - loops of fire alarm sensors (PI); MANUAL - a loop of manual start buttons; DC – a loop of control of provision of doors; workstation - automated workplace operator; 1 - fire alarm control panel; 2 – fire sensors (PI); 3 – fire extinguishing manual start buttons; 4 – door position sensors; 5 - water sprayers; 6 – water pump; 7 – fire extinguishing gas sprayers; 8 – gas start squibs; 9 – block disconnection from the network of process equipment; 10 – sound annunciator about the fire; 11, 12, 13, 14 – light alarms

When protecting unheated buildings, where there is a risk of water freezing, sprinkler installations of the water-air system are used, filled with water only up to control and signal valves, after which compressed air is in pipelines with sprinklers. When opening the heads, air first comes out, and then water begins to flow.

Rice. 34.2.

1 - water sources: 2 - the main water feeder; 3 – auxiliary water feeder make-up pipeline; 4 - auxiliary water feeder; 5 - control and signal valve; 6 - signaling device; 7 - distribution pipelines; 8 - sprinkler sprinkler

Drenchers of deluge installations, unlike sprinklers, do not have fusible locks, and their outlets are constantly open, and the water supply network itself is closed by a group action valve that opens automatically from the signal of fire detectors.

Sprinkler installations irrigate only that part of the room in which the sprinklers opened, and deluge installations irrigate the entire settlement part at once. These installations are used not only to extinguish a fire, but also as water curtains to protect building structures, equipment, and raw materials from fire. The estimated area of ​​irrigation by one water sprinkler of a sprinkler or deluge type is from 6 to 36 m2, depending on their design and the diameter of the through hole.

As a fire extinguishing agent, sprinkler and deluge installations can also use a foaming solution. Mixed sprinkler-drencher systems are also used.

The power supply of fire alarm systems and fire extinguishing installations must be carried out according to reliability category I (according to the PUE). That is, in the event of a power outage, the AUP and AUPS systems should be automatically transferred to backup power. The delay time is no more than the automatic switching time.

SP 5.13130.2009 defines a list of buildings and structures, individual equipment subject to protection by AUP and AUPS (Table 34.7). For example, buildings for public and administrative purposes, premises for accommodating personal computers protect AUPS regardless of their area, industrial premises with the presence of alkali metals when placed in ground floor with an area of ​​300 m2 or more - AUP, less than 300 m2 - AUPS, spray booths using flammable and combustible liquids - AUP, regardless of the area.

The type of fire extinguishing and alarm installation or a combination of them, the method of extinguishing, the type of fire extinguishing agent is determined by the design organization specifically for each object individually. This organization must have an appropriate license for the right to design such systems, install and maintain. The register of such organizations is maintained by the Ministry of Emergency Situations of Russia. After the commissioning of fire automatics installations, the head of the organization, by his order (instruction), appoints the persons responsible for their operation (usually these are employees of the departments of the chief mechanic, chief power engineer, instrumentation and automation service).

Daily round-the-clock control over the work of the AFS and AFPS is carried out by operational duty personnel (shift service, fire station), who must know the procedure for calling the fire brigade, the name and location of the premises protected by fire automatics (AFS, AUPS), the procedure for maintaining operational documentation and determining the operability of these systems.

The performance of automatic fire alarm installations is checked by exposing reusable detectors to exemplary (standardized) sources of heat, smoke and radiation (depending on the type of detector).

Table 34.7

List of buildings, structures, premises and equipment subject to protection by AUP and AUPS

For installations with single action detectors, the check is carried out by introducing artificial damage (break) performed in the most remote junction or branch box, which has "clamp" mounting terminals, or by disconnecting the most distant detector from the loop line.

Checking the performance of automatic fire extinguishing installations is carried out by visual inspection of instrumentation and assessing the health of individual components or checking the performance of the installation as a whole, which is carried out according to a specially developed program agreed with the State Fire Supervision Authority. Inspections are carried out at least once a quarter. Their results are formalized by the relevant act.

For a full-fledged broadcast of announcements, the communication system includes in its activities the complex use of telecommunication hardware and auxiliary means.

Hardware

The automatic control system refers to the engineering base for automation and informatization of garrison control, its most important component is a system that provides. It, in its action, covers the main divisions of the garrison.

The fundamental basis of its functioning is based on mobile and fixed communication nodes, which in turn are based on modern hardware, due to which their full control is performed.

The main communication tools include the following hardware:

1. technical communication devices (various radio stations, telecontrol equipment, radio transmitters, sound recording devices, telegraph station, radio repeaters, and other units whose main purpose is to receive (transmit) and convert various types of information);
2. uninterruptible power generators, precision instruments, rectifiers and chargers;
3. linear wire facilities (cables for underground and underwater purposes, light field communication cables that provide mobility, cables for long-distance communication, cables for distribution purposes, as well as auxiliary facilities, the main function of which is laying and building reliable communication lines);
4. means of communication signal type (lighting and sound).

Using an alarm in an alert

In order to quickly detect and immediately notify the fire department about the current critical situation caused by uncontrolled fire, as well as the place of its direct action, alarm means are used.

Today, preference is given to electric fire alarms (EPS). Given device installed sensor, which notifies of a dangerous situation, the automatic fire alarm system is divided into:

• devices, the activation of which occurs at the time of the appearance of smoke;
• devices that turn on with strong temperature fluctuations;
• devices that operate in the event of a fire;
• devices combined type.

In addition, other types of signaling are used: beam systems and loop-type systems.

Beam systems - are used in institutions located at a relatively short distance. Basically, the length of lines at such enterprises is insignificant.

If they are triggered, a special item will display information only about a certain number of a particular beam, without identifying a direct detector installed on the territory of the organization.

The loop-type warning system differs from the beam version of the devices in that the installation of the detectors takes place in one structured line (loop). Typically, such a design can include about fifty detectors.

The operation of this device is based on this principle - the signal is transmitted from the detector to the receiving station with a certain code. The installation of detectors in the loop takes place under different numbers, differing in their personal code. By fixing the received code, the receiving station determines the location and number of a specific detector.

As for the enterprises that deal with food products, their territories install differential and maximum thermal type detectors, as well as smoke-responsive and combined type detectors (smoke + heat).

Device type selection

Everyone knows the fact that a fire can go unnoticed for a long time. It can only manifest itself as a sluggish smoldering or have a hidden heat source, which, in turn, will flare up for a long time, since it will not have enough air.

The course of this stage can last quite a long time, about several hours. In this regard, an apparatus that notifies people of a fire only with an increase in temperature or the appearance of an open flame will be able to report a fire only when it is in full swing.

Based on this, the following conclusion can be drawn that the most effective detector will be a device that reacts to smoke and gaseous combustion products.

It is worth paying attention to the fact that detectors that react to smoke work faster than their counterparts, which signal a rise in the temperature level.

As devices notifying about the occurrence of smoke, ionization sensors are used. The ionizing substance in the chamber is plutonium, which produces alpha radiation. The operation of the sensor is based on changes in the electrical conductivity of gas accumulations that appear as a result of irradiation of a radioactive substance.

When ignition occurs, accompanied by smoke or its absence, even with the slightest release of heat, the properties of the atmosphere around us begin to change significantly, since ionization and a change in the composition of the gas occur. As a result of the described phenomenon, an ultra-sensitive detector of the DI type was produced.

This device is designed for long-term use and continuous operation at temperatures from -29 °C to +59 °C. The coverage of such a detector is 100 sq.m. Installation of such devices in buildings, the atmosphere of which is saturated with alkalis and acids, is irrational.

The most common representative of automated heat detectors is the PTIM-type heat detector (maximum action semiconductor heat detector). In the case of raising the temperature level in the room, the sensor responsible for the thermal resistance sharply reduces its effect, which in turn leads to an increase in the voltage on the control electrode.

As soon as this voltage exceeds the permissible level, the ignition voltage will begin its action, that is, the detector will be activated. The area of ​​its impact is 10 m 2 .

According to the principle of the sensitive element used, automated detectors are divided into:

• semiconductor;
• bimetallic;
• on thermocouples.

Detectors functioning according to thermal principle works are divided into the following types:

• maximum differential;
• differential;
• maximum.

ATIM are detectors of the maximum type. They begin to operate when the temperature in the building reaches a peak. These devices can be adjusted and configured to operate from +60 to +80 °C, regardless of the rate of temperature increase. The frequency of operation of the device is up to 2 minutes. Coverage area is 15 sq.m.

The differential type of detectors shows its activity during the period of temperature increase, which increases at a certain rate. So, for example, the TEDS device reacts within seven seconds to sharp fluctuations in the increase temperature regime(30 degrees). The control area is 30 sq.m.

Detectors of maximum differential action are activated when the temperature level rises in a certain room. The DMD detector responds after no more than 50 seconds. Covered control area - 25 sq.m.

In addition, thermal type detectors have one very significant drawback - the time from the start of activation and giving an alarm signal can be several minutes.

To date, models of a combined type are actively used, which react to heat and smoke.

The main component of the combined action detector is an electrometric thyratron, the principle of its operation is based on the interaction of two sensors: a heat controller and a device that reacts to smoke.

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Fire communications and alarms are organized to quickly and accurately receive fire messages, call additional forces in a timely manner, maintain communication with units on the way and at the fire site, communicate between units on fire, transfer information to officials about the progress of fire extinguishing, for everyday operational communications between departments and officials.

The central fire communication point is connected to the city automatic telephone exchange (ATS) by special lines.

Fire alarm systems are used to detect and notify the location of a fire. The combined fire and security alarm system performs the functions of protecting objects from unauthorized persons and fire alarms.

The main elements of a fire and security fire alarm system: fire detectors, receiving stations, communication lines, power supplies, sound or light signaling devices (Fig. 15.2).

According to the method of connecting the detectors to the receiving station, beam (radial) and loop (ring) systems are distinguished (Fig. 15.3).

Rice. 15.2. Fire alarm installation diagram

Rice. 15.3 Scheme of the device of electrical fire alarm systems:

a- radial (radial); b- loop (ring); 1 - announcers - sensors; 2 - receiving station; 3 - battery backup power supply; 4 - mains power supply; 5 - switching system from one power supply to another; 6 - wiring

Fire detectors can be automatic and manual. Depending on the activation parameter of the fire detector, they are: thermal, smoke, light, combined, ultrasonic and manual.

Heat detectors are triggered when the ambient temperature rises, smoke detectors - when smoke appears, light detectors - in the presence of an open fire, combined - when the temperature rises and smoke appears, ultrasonic - when the ultrasonic field changes under the influence of fire, manual - when turned on manually.

According to the design, fire detectors are of normal design, explosion-proof, intrinsically safe, sealed. According to the principle of operation, they are divided into maximum, triggered at a certain value of the absolute value of the controlled parameter, and differential, responding only to the rate of change of the parameter and triggered at a certain value.

Fire detectors are characterized by sensitivity, inertia, coverage area, noise immunity, design.

Automatic fire detectors send signals based on different principles electrical circuit closure (change in the electrical conductivity of bodies, contact potential difference, ferromagnetic properties of materials, change in the linear dimensions of solid bodies, physical parameters liquids, gases, etc.).

Thermal detectors of differential action type DPS-OZ operate on the principle of different increase in thermo-EMF in blackened and silvered layers of thermocouples. They are triggered by a rapid increase in temperature (at a speed of 30 ° / s), have an estimated service area of ​​\u200b\u200bthe room up to 30 m 2 and can be used in explosive rooms.

For signaling from manual and heat detectors, receiving stations of the TLO-30 / 2M type (alarming, beam, optical) for 30 beams are used with a radial scheme for connecting detectors of the PICL-7 type with the station.

The performance of multiple heat detectors is checked at least once a year with a portable heat source (150 W electric lamp with a reflector). The detector is operational if it is triggered no later than 3 minutes from the moment a heat source is brought to it.

Smoke detectors are divided into photoelectric and ionization. Photoelectric detectors (IDF-1M, DIP-1) operate on the principle of scattering of thermal radiation by smoke particles. Ionization - use the effect of weakening the ionization of the air interelectrode gap with smoke.

For example, an alarm smoke fire installation of the SDPU-1 type is designed to detect smoke, followed by the supply of light and sound signals and control of external electrical circuits of automatic fire extinguishing devices. It is designed for 10 beams of the electrical network with 10 detectors connected to each beam. The 220 V network is insured by the battery supply.

Combined heat and smoke detectors have a sensitive element in the form of an ionization chamber (to respond to smoke) and thermistors (to respond to heat). The response temperature is 50-80 ° C. The estimated service area is 100 m 2.

Smoke and combined detectors are checked at least once a month with portable sources of smoke and heat. The detector response time is not more than 10 s. Install them in rooms in which there is no dust, vapors of acids and alkalis.

In light detectors, the photoelectric effect is used to detect a fire, i.e. conversion of light energy into electrical energy. In the premises where such detectors are installed, there should be no sources of ultraviolet and radioactive radiation, open flames, working welding machines etc. Light detectors are checked by the flame of a candle or match.

An ultrasonic detector (for example, Ficus-MP) is designed to spatially detect a fire and give an alarm. Such detectors are inertialess and serve a large area (up to 1000 m 2), but they are expensive and have the possibility of false alarms.

Thermal and lighting - in rooms with equipment and pipelines for pumping, producing and storing varnishes, paints, solvents, GZH, flammable liquids, for testing internal combustion engines and fuel equipment, filling cylinders with combustible gases.

Smoke - in rooms for electronic computers, electronic regulators, control machines of automatic telephone exchanges, radio equipment.

Thermal and smoke - installed in places where cables are laid, in rooms for transformers, distribution and switchboard devices of enterprises servicing cars, in which products made of wood, synthetic resins and fibers, polymeric materials, celluloid, rubber, textile materials, etc. P.

One of the conditions for a successful fight against fires is their timely detection, early notification of fire services and the start of active fire fighting at the initial stage of fire development. These tasks are solved with the help of fire communication and signaling. Fire communication provides notification of a fire and calling fire fighting services, dispatch communication for managing fire extinguishing forces and means, and operational communication of units during fire extinguishing. Fire communication is carried out through a city or special telephone network, or short-wave transceiver systems.

Fire alarm (PS) is a basic element in the security system of any enterprise.

Every enterprise, every office must have such a system. This is dictated both by the desire of the owner to protect his property, life and health of employees, and by state standards and regulations Ministry of Emergency Situations. In general, a fire alarm system is designed to detect a fire at the initial stage of ignition and transmit an alarm signal to the security console. PS- is a complex set of technical means that serve for the timely detection of fire in a protected area.

Fire alarm system consists of the following main components.

1. The control panel is a device that analyzes the state of fire detectors and loops, and also gives commands to start fire automatics. This is the brain of the fire alarm.

2. Display unit or automated workstation (AWP) based on a computer. These devices serve to display the events and status of the fire alarm.

3. Uninterruptible power supply (UPS). This block serves to ensure continuous operation of the alarm, even in the absence of power supply. This is the heart of the fire alarm.

4. Various types fire detectors (detectors). Sensors are used to detect the source of fire or combustion products (smoke, carbon monoxide, etc.). These are the eyes and ears of the fire alarm.

Types of fire detectors

The main factors that a fire alarm responds to are the concentration of smoke in the air, temperature rise, the presence of carbon monoxide CO and open fire. And for each of these signs there are fire detectors.

Thermal fire sensor responds to temperature changes in the protected room. He can be threshold, with a given response temperature, and integral, responding to the rate of temperature change. They are mainly used in rooms where the use of smoke detectors is not possible.
Smoke fire detector reacts to the presence of smoke in the air. Unfortunately, it also reacts to dust and fumes. This is the most common type of sensor. It is used everywhere except smoking rooms, dusty rooms and rooms with wet processes.
Flame sensor reacts to an open flame. Used in places where fire is possible without prior smoldering, such as carpentry workshops, storage of combustible materials, etc.

The latest invention in the field fire fighting systems- this is multisensor detector. Developers have long been puzzled by the problem of creating a sensor that would consider all the signs in the aggregate, and, therefore, would more accurately determine the presence of a fire, by an order of magnitude, reducing false alarms of a fire alarm. The first to be invented were multi-sensor sensors that respond to a combination of two signs: smoke and temperature increase. Now sensors are already being used that take into account a combination of three and even all four factors. Today, many companies already produce fire protection systems with multi-sensor sensors. The most famous of them are System Sensor, Esser, Bosch Security Systems, Siemens multi-sensor smoke detector, etc.