Automatic fire extinguishing system (AUPT)

No one needs to tell how dangerous any fire is, and how hard it is to fight with fire, which is capable of destroying the results of many years of human hands together with the man himself in a matter of hours. However, before it was. However, time goes by, and with it science develops. Today, people have learned to fight with fire and learn about the threat of the development of a fire at a time when the flame has just appeared, and it is not difficult to cope with it. All this became possible with the advent of a device such as an automatic fire extinguishing system.

What it is? What are the objectives pursued?

Automatic systems and installations for fighting fire, as a rule, are part of a set of devices designed to provide general fire safety of a building or structure. Their main purpose is to prevent the spread of the flame and to enter into the struggle with the elements at the earliest stages.

These devices are not mandatory components of the fire fighting system. However, in those facilities where there is an increased threat of fire and rapid spread of the flame, and where there is no possibility of emergency evacuation of people caught in the fire zone, the automatic fire extinguishing system (APA) can be said to be simply irreplaceable.

Automatic system of fighting fire can be called a set of devices that is able to independently activate itself when exceeding the parameters and factors controlled in the protected zone with respect to threshold values.

A distinctive feature of these devices is the performance by them of the functions of automatic fire alarm. These elements, which are usually included in the general fire-fighting system, must ensure the achievement of one, or better, several purposes, the main of which are:

- elimination of the flame on the protected object until the critical values of the ignition factors are reached;

- liquidation of fire before the fire resistance limit of building structures on the site comes;

- liquidation of a fire earlier than the maximum damage to property and material values;

- the termination of burning processes before there is a danger of destruction of technological installations with which the protected object is equipped.

Further among the most important functions that automatic fire extinguishing systems must necessarily perform, there is such as emergency assistance in providing a secure stay zone for people on site.

Options for existing automatic installations

At the moment, there are many options for automatic installations for fighting fire. You can classify them by several parameters. By design, these devices can be modular, modular, deluge and sprinkler. By the way they extinguish the fire, they can be voluminous, in area and local.

By the way of operation (or start-up) of the installation, they can be subdivided into manual, automatic and with different kinds of drives (electric, hydraulic, pneumatic, mechanical, combined).

For such a factor as inertia, automatic fire extinguishing systems can be divided into ultra-fast, fast or small inertia, medium inertia and high.

In addition to the above, fire extinguishing installations are classified according to the duration of the fire extinguishing agent supply. They can be impulsive, short-term, medium-duration and long-term exposure.

However, both among specialists and among ordinary consumers, the most famous is the classification according to the type of substance used to extinguish the flame. For this factor automatic fire alarm and fire extinguishing systems can be divided into water, foam, gas aerosol, powder and steam.

Foam-based plants

Automatic installation of foam fire extinguishing is one of the most difficult, because it additionally includes mechanisms that convert the powder from a specific composition to foam (they are called sprinklers or steam generators). In addition, in foam plants (in particular in the fire pipeline), special containers or tanks should be provided in which the foam concentrate or the already prepared composition will be stored.

The use of the finished composition and the preparation of foam directly in the process of extinguishing the fire are two incompatible different principles of the AUPT. For each of these methods, both positive and negative aspects are characteristic. If we draw a boundary between them purely conditionally, then we can say that the automatic fire extinguishing system, in which the foam concentrate and water storage are stored separately, will be more effective for protecting large areas.

Installations with ready-to-use composition are more suitable for eliminating flames in small areas, because there are a number of shortcomings that appear when storing sufficiently large amounts of foam mass. Of the most significant, we can distinguish the following. The finished composition has a short shelf life, i.e., it must be regularly changed, which entails an increase in cash costs (in proportion to the size of the reservoir). Further, if the required head is able to provide a fire water supply, then it makes no sense to invest in the construction of a large reservoir. In addition, contact foam composition and concrete is unacceptable, that is, it is necessary to cover the inner surface of the storage tank with epoxy mastics, which, again, increases the cost. And large tanks greatly complicate the processes of recycling old foam and replacing it with a new one.

Automatic installation of foam fire extinguishing will prove to be most effective in the conditions of application in chemical and petrochemical enterprises, where many highly inflammable liquids are stored. It is also justified to use them in warehouses and hangars with machinery, that is, where there are usually few people and there is no way to quickly evacuate material values.

Water plants for fighting fire

Installations that use water in their work are the most universal in comparison with all the others, as they can be used where people's safety and the possibility of their emergency evacuation are the goal priority for all the rest (offices, government agencies, etc.).

Installations using water to extinguish fires can be divided into two types: local (sprinkler) and protecting the entire building (deluge).

Automatic installation of sprinkler fire extinguishing (from English sprincle - "drizzle, sprinkle") is equipped with a fully autonomous response system. When a temperature is recorded at a point on the protected surface of the temperature increase, it automatically activates and sends a stream of finely atomized liquid as close to the heat source as possible.

If you select the APCT as the preferred water source, you should pay attention to the type of control node ("dry" or "wet"). The former are mainly used on unheated objects and premises, and the latter ("wet") - where the temperature is never below zero.

Deluge installations of water fire extinguishing (automatic), unlike sprinkler ones, are never autonomous. They always work in tandem with a fire alarm system, which activates them. Deluge devices are not equipped with sensors that would determine the location of the source of increased heat dissipation and coordinate their work in this direction. These plants, during operation, cover all available surfaces in the protected area with water.

If the preference is given to the water variants of the UAAT, it must be remembered that water is capable of reacting with some organometallic compounds and compounds. The result of such reactions can be the release of toxic substances into the air, which, of course, will create conditions that prevent the evacuation of people, and can damage their health. For this reason, the use of automatic water-type fire extinguishing systems is generally unacceptable on those industrial facilities where coal, iron, metal carbides are involved in the production cycles, etc. Also, the necessary effect will not be achieved when water-based APCs are Use to eliminate flames in rooms in which flammable liquids with a combustion temperature of not more than 90 degrees are stored.

The TRV installation

Currently, a new unique technology for the operation of a water fire extinguishing system has been developed and successfully implemented. Automatic devices of the new generation do not cover all the accessible surfaces with a thin layer of water, but spray the liquid with small droplets directly into the flame. The liquid evaporates, thereby binding the fire. Such means are called fire extinguishing installations with fine dust (TRV). In addition to the binding of open fire, evaporation of the liquid leads to an increase in vaporization. Steam, in turn, reduces the amount of free oxygen contained in a closed space and thereby suppresses the possibility of combustion processes. The result of the impact of such installations is the maximum localization of the source of ignition, its separation and complete extinction of the flame.

Automatic fire extinguishing systems with the use of thin spray technology effectively work in places where highly inflammable formulations and liquids are stored. Also, such APCTs can stop the combustion process, provoked by sharp voltage drops in the power grid. In such cases, most often you have to deal with fire when extinguishing live electrical equipment. Provided that the water sprayer and the burning object are located at a distance of at least 1 m, the permissible voltage values may reach 36,000 V.

In addition, a cloud of the smallest droplets of water is an excellent absorbent, binding pairs of carbon monoxide, ash and other particles that can cause serious damage to the respiratory organs of a person. The process of extinguishing a fire by installing a TRV does not prevent the evacuation of people (if necessary) and the protection of material values.

From the minuses of such devices is the inability to use them in places where there is a risk of contact with organometallic compounds.

Installations of gas type

Modern liquefied fuels or compressed nitrogen, argon, inert gas make it possible for a person to defeat fire in places where liquid facilities can not be used for this purpose (rooms where short circuits can occur , information storages, libraries, museums, aircraft).

In the rooms protected by gas AUPT, upon the occurrence of the fact of operation, devices and mechanisms of light (the inscriptions "Gas - go!" And "Gas - do not enter!") And sound notification of a fire should be switched on. These are the requirements of the GOST system.

Gas extinguishing installations (automatic) create an environment where the development of fire is impossible in principle. This is very convenient for rooms with a high risk of spreading the flame. If the area of the fire is low and the introduction of significant volumes of gas is not required, such fire extinguishing is possible even without prior evacuation of people. However, one must know that gas in large doses can cause serious damage to human health.

The use of gas fire extinguishing installations is justified in cases of fire in electrical supply rooms, at power plants and power plants (extinguishing generators in the case of hydrogen cooling), at facilities for the production of light-fuel materials, long-distance transport, in warehouses with valuables. In libraries and museums, such installations can be used provided that exhibits and rarities under glass are stored.

It should be remembered that an automatic fire extinguishing system based on gas will not be effective where materials can burn without the participation of oxygen in this process. Do not use such devices and in cases where materials are prone to spontaneous combustion and decay (wood shavings, rubber, cotton, etc.), for certain types of metals that can react with gases for pyrophoric materials.

Fire extinguishing systems based on powders

Currently, most often (about 80% of cases), all the previously described types of automatic fire extinguishing systems are inferior to the UAPT powder type. This breadth of application is due to a number of advantages. First, these devices are quite versatile (it is possible to use even to extinguish electrical installations). Secondly, the shelf life of the reagent is long enough, its disposal is not very difficult. In addition, such UAPT have a high temperature limit, and they are non-toxic.

Powder-type plants are able to fight fires of Class A, B and C, which significantly expands their capabilities in eliminating fires at remote sites, where sometimes you have to wait a long time for help.

Installation of automatic fire extinguishing with the use of powders is effective in fires in oil-loading and pumping facilities, when working with electrical points and nodes. However, the desired result will not be achieved if materials burned that do not need oxygen to support this process, as well as those that are prone to spontaneous combustion and decay.

Powder fire extinguishing devices are incompatible with anti-smoke ventilation systems. And since the latter must necessarily be present in places where people are constantly located, the powdered UAPT has industrial objects, warehouses and tunnels.

Aerosol type devices

Automatic installation of aerosol fire extinguishing is a highly specialized device. They can not be used to extinguish the ignition of potentially explosive substances, as well as where people are constantly present. The composition of the aerosol itself is harmless in principle and is not capable of causing any serious harm to health. However, when activated autonomously, automatic fire alarm and fire extinguishing systems based on aerosol do not allow people to see where the evacuation routes are.

Due to the high efficiency of these automatic fire alarm systems, a fire before its complete elimination can be allowed to people in the building. But here it is important to trace and take the necessary measures to prevent the explosion of the plants themselves due to the large amplitude of fluctuations in internal pressure with respect to external temperatures.

Aerosol type devices proved to be very useful in those cases when it was required to extinguish fires caused by malfunctions in the power grid. Such installations are also effective in the fight against fires of technogenic origin. This is an ideal tool for providing fire safety for large vehicles, oil facilities, etc.

However, such an automatic fire extinguishing and alarm system using aerosols is not capable of completely eliminating smoldering in the inner layers (porous, fibrous materials) and burning without the presence of oxygen.

Settings for autonomous operation and impact

Above the text in most cases, automatic stationary fire extinguishing systems were described, but along with them there is also the concept of an autonomous system for fighting fire. What it is?

The stand-alone installation is capable of independently detecting a source of increased heat loss and deciding whether to activate the fire-fighting process. These devices can be fully included in the UAPT water and gas species. Such systems, as a rule, are equipped with special sensors sensitive to temperature increase or identifying the corresponding particles in the air composition. If such factors are fixed, the sensors transmit the signal to their own panel for analysis and commands in order to activate the work process (in case of an obvious fire hazard). For different types of installations, the sequence of actions may differ slightly, but in most cases the algorithm is permanent: "identification - request - activation".

So, mandatory components that are part of the stand-alone automatic fire extinguishing systems are detection and start-up devices and, in fact, devices for direct fire extinguishing. The first, of course, can be called the most important node of an autonomous installation. Detection and start-up devices include fire detectors equipped with a power supply battery or generating EMF using an induction coil. Also, these devices include a fire cord, a thermal lock and an initiating powder.

In addition, often in stand-alone installations it is possible to manually start the system, which allows you to activate the workflow, without waiting for the moment when the temperature in the protected zone exceeds the critical values. This function is very, very useful, since a person can often feel and react to the signs of a developing fire (temperature rise, smell, smoke, etc.) much earlier than a mechanical sensor system does.

Price range

Installing automatic stationary fire extinguishing systems to protect their own households, it is important to maintain a balance, without trying to save where it is unacceptable, but without investing too much, since fire is a rare phenomenon, and the maintenance of a firefighting system for finance is comparable to its original value.

Today, the cheapest are the UAPT powder and aerosol type, because they cause irreparable damage to material values and are mostly dangerous for plants and animals. Gas installations are slightly more expensive: there is no harm to property, but tightness of premises and preliminary evacuation of people is required. Foam installations are even more expensive, but not at all applicable in private housing construction and are ideal for storage rooms and hangars with machinery.

The most expensive ones can be called fine-spray water spray systems, which in no way hinder the evacuation of people, allow the fire to wait in the room until it is completely eliminated and do no harm to material values. The liquid droplets are so small that they are in contact with the flame and evaporate without reaching the surfaces. Also in the process of fire fighting, steam is formed, which prevents the spread of fire and lowers the temperature in the room.