Fire extinguishing substances: classification, application features

The operation of modern fire extinguishing systems involves the use of a wide range of substances, through which the fight against fire is realized. Traditionally, the main substance of this kind is water. Indeed, this is the most popular filling of fire fighting installations, but far from all this method is effective. Therefore, other types of fire extinguishing substances are introduced into the working arsenal of fire services, the properties of which are developed and servicing technical means. So there are all the new powder components, liquid formulations and aerosols, gas and other versions of substances that can successfully fight the flame.

Classification of extinguishing agents

The basic principle of separating fire extinguishing substances is based on the nature of the effect on the fire. The most common way to do this is to cool the combustion zone. In the process of extinguishing, the supply of materials active from the standpoint of cease-fire is carried out. At the same time, fire department staff should, if possible, mix structural elements and disassemble burning materials, allowing more effective cooling of the affected surfaces. The following principle is based on the dilution of the reacting elements. In this case, the extinguishing agents are volatile or decomposing non-combustible materials, the coating of which contributes to a cease-fire. Also, insulating materials that affect the activity in the combustion zone by creating special barriers, bridges, etc., are common.

There is another classification of extinguishing materials, which is based on the physical state of the substance. In particular, liquid, gaseous, loose, solid, as well as fabric fillers of fire systems are isolated. It should be noted that the affiliation of fillers to different groups in accordance with this classification does not bind to the separation system mentioned above. That is, the classification of fire-extinguishing substances according to the principle of impact on the fire zone can allow entry into one of the categories of two or more materials with different physicochemical properties.

Cooling agents

Theoretically, combustion can be stopped if at high speed it is ensured the removal of thermal emission. This principle can be realized through the use of refrigerants, which through cooling control the process of heat removal, minimize the activity of the source of combustion. A classic representative of a group of cooling materials is water - a fire extinguishing agent that has high heat capacity, availability and chemical inertness.

Like all universal materials, this fluid has drawbacks. First of all, water is characterized by increased electrical conductivity, which in itself imposes serious limitations on its use. The situation is aggravated when the liquid is mixed with other additives, increasing the ability to conduct current. But this is not all the shortcomings. Water also has poorly expressed ability to adhere to relatively burning materials, because of what, in fact, it adds special additives. As a result, other extinguishing substances are obtained, which are various mixtures and solutions, usually on a salt basis.

Insulating substances

The most common material in this group is foam. The insulating effect contributes to the effective suppression of the flame with minimal loss and risk in terms of toxic safety. The structure of the foam forms a colloidal system of liquid bubbles that have a gas filling. Often, such substances have a double effect - insulating and cooling. At the same time, not all foam extinguishing agents can be used in extinguishing fires. For example, a soap solution diluted at home will not have any effect, since in the fire the emulsion structure will instantly be destroyed. Therefore, special solutions are used that have a relatively strong bubble structure capable of withstanding thermal and mechanical effects. In order to strengthen the foamy substance, special stabilizers are added to the solution compositions. Also with the foaming agent, the use of air emulsions is also combined.

In the category of insulating materials it is necessary to include powders intended for extinguishing fires. Although such substances are universal and have a multifactorial overwhelming effect on fire, nevertheless the ability to isolate sources of fire comes first. For such purposes, for example, a fire extinguishing powder is used based on alkali metals, carbonate, bicarbonate, ammonium salts and other compounds. Also, such substances are used purposefully in extinguishing electrical equipment.

Dilution substances

This is a vast group of substances that are mainly oriented to use in special fire extinguishing conditions. For the cease-fire, materials capable of either diluting flammable vapors with gases to a non-combustible concentration or minimizing the oxygen content in the air to a level where combustion ceases to be maintained are used in this way. Various approaches to the supply of materials can be used, for example, in a general fire zone, into the air, or purposefully into a combustion object.

According to the practice of application, the most popular means of this type is carbon dioxide, which provides the most effective cessation of burning in a fire. Fire extinguishing agents in the form of nitrogen and water vapor are also useful depending on the conditions of use. For example, water vapor is used mainly for extinguishing fire in enclosed spaces and hard-to-reach places. During the processing of the object, water vapor fills the entire room, diluting and displacing the air masses from it. Thus, the active substance prevents combustion, without adversely affecting the people in the room. In addition, sometimes there is a double effect of quenching the flame with steam. Firstly, the cloud itself is acting, replacing the air. Secondly, the droplets formed from the vapor evaporate and absorb heat from the source of the fire.

Chemically active substances

This is a category of substances that exert a retarding effect on the combustion process. The principle of suppression is based on the chemical effect of the agent on the fire zone. Upon contact of the extinguishing agent with the target object, interaction with the active sites of the oxidizing reaction occurs, resulting in non-flammable or low-active compounds ceasing the combustion reaction.

Halogenated hydrocarbons are able to provide such an effect. These are extinguishing agents with an inhibitory effect that inhibit the activity of the combustion process. But it is important to consider that such materials are dangerous to toxic effects. As for the effectiveness of quenching, this is probably the best group of materials for firefighting. But, again, undesirable chemical activity significantly limits the scope of application of such substances. If we talk about specific compounds, the inhibitory substances can be represented by freons and other halogenated compounds based on ethane and methane. Specialists call such materials chladones, attributing to them special designations with an indication of the chemical composition. In accordance with the marking, the acceptable conditions for the application of substances are determined.

Mobile and stationary fire extinguishing means

The very effectiveness of substances that theoretically can help in the fight against fire is minimal if there is no well-established system of supplying the material. For this purpose mobile and stationary installations are used, which carry out the introduction or spraying of the active substance. Mobile means include fire trucks that are operated by security services. However, these are not just ordinary cars with personnel. In the same category, it is possible to include trains, airplanes and sea vessels that carry out fire extinguishing in appropriate conditions. Also common are fixed fire extinguishing installations, which are intended for the release of a fire extinguishing agent. For example, such systems are most often used in closed rooms and work with diluting active materials.

Among the main tasks that stationary installations perform, one can note the elimination or, as a minimum goal, the localization of a fire. In this case, there are many options for structural design of such complexes. In particular, modular and aggregate systems are distinguished. Also against a background of wide automation of safety systems depart from manual control and installation of fire extinguishing, supplemented by modern electronics and the newest remote control systems.

The use of fire extinguishing substances in the monitors

Fire-extinguishing media supply fire extinguishing materials, as a rule, are projected even at the stage of construction of the facility in which they will be installed. The fact is that such systems are the most demanding for communications, so the initial calculation of their location and installation is especially important. Typically, such units are used in production facilities, which also accommodate tanks for extinguishing agents of a particular type. This can be, for example, water tanks or cylinders with foam or gas filler. Some modifications, by the way, are not intended just for the complete elimination of the flame. Their main tasks are to protect the production equipment or communications - for example, by water irrigation.

Installations of this type can differ in the method of the device. It is not always the case that the fluting structures have a stationary position. It can be mobile fire trunks with the addition in the form of software or remote control. Of course, stationary installations are also common, the supply of extinguishing agents in which is often carried out through general engineering networks and communications. This connection allows you not to waste time organizing the operating infrastructure and immediately start the fire fighting process.

Automation in fire extinguishing installations

Modern automatic fire fighting systems allow, regardless of the person's participation, to control the factors that indicate the danger of a fire, and start the extinguishing process in a timely manner. Usually, at the time of exceeding the values set in the program, the supply of the active substance begins and, together with this, the alarm is triggered. In this case, there are different approaches to the management tools of such systems. For example, sprinkler models are fully automated, but there are other systems in which manual control is provided. Thus, the extinguishing agent in gas extinguishing installations can be produced both automatically and by the operator's command through the control panel. But such a control system already depends on the type of installation itself - the modular ones are oriented towards greater autonomy, while centralized systems allow a maximum range of approaches to management.

It is important to note the safety factors that can not always be taken into account when operating automatic systems. Equipping with such installations justifies itself only in those cases when the elimination of fires with primary instruments is impossible. Also at some production facilities, the personnel do not service the security systems around the clock. Obviously, in such situations, one can not do without an automatic means of fighting fire. Another thing is that in order to minimize risks, it is necessary to make the right choice of the extinguishing agent from the very beginning, the automatic delivery of which, as a maximum, will entail only the planned and pre-calculated damage.

Classification of installations for extinguishing agent

For each type of extinguishing installation, a specific type of active substance is used. For safety, the use of several materials in one complex is rarely practiced. The most common system is the design with water fire extinguishing. Especially common deluge complexes, which are used to protect premises with a high risk of fire. The effectiveness of such devices is due to the fact that they can provide simultaneous irrigation of the entire area of the protected area. In its composition deluge fire extinguishing systems include pumping equipment, control panels, pipelines, water tanks, warning devices, etc.

The second most popular substance, which is used in deluge designs, is foam. Such systems are used to protect local areas in production facilities, to prevent the ignition of transformers and electric appliances. Sprinkler installations with a foam fire extinguishing material are also widely used. By the way, such units have much in common with water installations except for special approaches to dosing. These are the main fire-extinguishing agents used in stationary and mobile means of combating fires, but there are specialized gas systems, powder and aerosol. Typically, fire-protection equipment with such fillers is used in special conditions - for example, in places where increased requirements for the maintenance of electrical equipment.

Conclusion

With all the variety of substances used in modern firefighting systems, experts still can not name the universal and most effective way to combat fire. There is a fairly clear segmentation of materials by class, depending on their technical and operational qualities. At the same time, the effect of fire extinguishing substances on a person and objects that are in the ignition zone plays an important role. For example, extinguishing systems with chemical fillers could well be the only means of suppressing fire. As practice shows, a minimum amount of fire extinguishing material of this type is required to combat fires in the middle classes.

But the problem is the consequences that involve the use of chemically hazardous substances. For this reason, technologists master new methods of firefighting, including structural ones. An effectively working substance for extinguishing a fire can reveal its full potential only in the only case if the system of combating foci of ignition was correctly organized. And in this regard, it is worth noting the importance of the basic facilities that provide material for extinguishing, and methods of control - automatic or manual.