The operation of modern fire extinguishing systems involves the use of a wide range of substances, thanks to which fire control is implemented. Traditionally, the main substance of this kind is water. Indeed, this is the most popular filling of fire fighting installations, but by no means in all cases 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 serving technical means. So there are all new powder components, liquid compositions and aerosols, gas and other types of substances that can successfully fight the flame.
Classifications of extinguishing agents
The basic principle of the separation of extinguishing substances is based on the nature of the effect on fire. The most common way to do this is to cool the combustion zone. In the process of extinguishing, active materials are supplied from the point of view of the ceasefire. At the same time, firefighters should, whenever possible, mix structural elements and disassemble burning materials, allowing more effective cooling of affected surfaces. The following principle is based on the dilution of reactive elements. In this case, fire extinguishing agents are volatile or decomposable non-combustible materials, the coating of which contributes to the ceasefire. Insulating materials are also common, which affect the activity in the combustion zone by creating special barriers, jumpers, etc.
There is another classification of extinguishing materials, which is based on the physical state of the substance. In particular, liquid, gaseous, free-flowing, solid, as well as fabric fillers of fire installations are emitted. It should be noted that, in accordance with this classification, the fillers do not belong to different groups in any way associated with the separation system mentioned above. That is, the classification of extinguishing agents according to the principle of impact on the fire zone may allow two or more materials with different physicochemical properties to enter into one of the categories.
Coolants
Theoretically, combustion can be stopped if heat release is provided at high speed. This principle can be implemented through the use of refrigerants, which, through cooling, regulate the heat removal process, minimize the activity of the combustion source. A classic representative of the 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 restrictions on its use. The situation is aggravated when the liquid is mixed with other additives that increase the ability to conduct current. But this is not all the disadvantages. Water also has poorly expressed adhesion to relatively burning materials, which is why, in fact, special additives are added to it. As a result, other extinguishing substances are already 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 foam structure is formed by a colloidal system of liquid bubbles that are gas-filled. Often such substances have a double effect - insulating and cooling. Moreover, not all foam extinguishing agents can be used in extinguishing fires. For example, a soap solution diluted at home will not give any effect, since in a fire the structure of the emulsion will be instantly destroyed. Therefore, special solutions are used that have a relatively strong bubble structure that can withstand thermal and mechanical influences. In order to strengthen the foamy substance, special stabilizers are added to the solutions. The use of air emulsions is also combined with a foaming agent.
Powders for extinguishing fires should also be included in the category of insulating materials. Although such substances are universal and have a multifactorial inhibitory effect on fire, the ability to isolate fire sources comes to the fore. For such purposes, for example, an extinguishing powder based on alkali metals, carbonate, bicarbonate, ammonium salts and other compounds is used. Also, such substances are used purposefully in extinguishing electrical equipment.
Dilution Substances
This is an extensive group of substances that are mainly focused on the use in special fire fighting conditions. To cease fire in this way, materials are used that can either dilute flammable vapors with gases to a state of non-combustible concentration, or minimize the oxygen content in the air to a level where combustion ceases to be maintained. In this case, various approaches to the supply of materials can be applied - for example, into a common fire zone, into the air, or purposefully into a combustion object.
According to application practice, the most popular tool of this type is carbon dioxide, which provides the most effective cessation of combustion in a 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 fires in enclosed spaces and inaccessible places. During the processing of the object, water vapor fills the entire room, diluting and displacing air masses from it. Thus, the active substance prevents burning, without exerting a harmful effect on people in the room. In addition, sometimes provides a double effect of extinguishing the flame with steam. First, the cloud itself acts as a substitute for air. Secondly, droplets formed from steam evaporate and absorb heat from the source of the fire.
Chemically active substances
This is a category of substances that have an inhibitory effect on the combustion process. The extinguishing principle is based on the chemical effect of the product on the fire zone. Upon contact of the extinguishing agent with the target object, it interacts with the active centers of the oxidizing reaction, as a result of which non-combustible or inactive compounds remain that stop the combustion reaction.
Halogenated hydrocarbons are capable of providing such an effect. These are extinguishing agents with an inhibitory effect, which inhibit the activity of the combustion process. But it is important to consider that such materials are dangerous by toxic effects. In terms of extinguishing efficiency, this is arguably the best group of extinguishing materials. But, again, undesirable chemical activity significantly limits the scope of such substances. If we talk about specific compounds, then inhibitory substances can be represented by freons and other halogenated compounds based on ethane and methane. Specialists call such materials freons, attributing them special designations indicating the chemical composition. In accordance with the marking, the permissible conditions for the use of substances are also determined.
Mobile and stationary fire extinguishing means
By itself, the effectiveness of substances that theoretically can help in the fight against fire is minimal if there is no established system for supplying material. For this purpose, mobile and stationary installations are used, carrying out the introduction or spraying of the active substance. Mobile vehicles include fire engines that are operated by security services. However, these are not only ordinary cars with personnel. In this category, you can include trains, planes and ships, carrying out the elimination of fire in appropriate conditions. Fixed fire extinguishing installations are also common, which are designed to release a fire extinguishing agent. For example, such systems are most often used in enclosed spaces and work with diluting active materials.
Among the main tasks that stationary installations carry out, it is possible to note the elimination or, as a minimum goal, the localization of the fire. Moreover, there are many options for structural designs of such complexes. In particular, distinguish between modular and aggregate systems. Against the background of wide automation of security systems, they are moving away from manual control and fire extinguishing systems, supplemented by modern electronics and the latest remote control systems.
Application of fire extinguishing agents in fire monitors
Fire-fighting means for supplying extinguishing materials, as a rule, are designed at the stage of construction of the facility, in which they will be installed. The fact is that such systems are the most demanding on communication support, so the initial calculation of their location and installation is especially important. Typically, such units are used at production facilities, where containers for extinguishing agents of a particular type are also located. It can be, for example, water tanks or cylinders with foam or gas filling. Some modifications, by the way, are not designed specifically to completely eliminate the flame. Their main tasks are to protect production equipment or communications - for example, by water irrigation.
Installations of this type may differ in the method of the device. Far from always, the monitors are stationary. It can be mobile fire trunks with the addition of a program or remote control. Of course, stationary installations are also common, the supply of extinguishing agents in which is often carried out through common engineering networks and communications. Such a connection allows you not to waste time organizing a working infrastructure and immediately start the process of fire fighting.
Automation in fire extinguishing installations
Modern automatic fire-fighting installations allow, regardless of human involvement, to control factors that indicate the danger of fire, and to begin the process of extinguishing in a timely manner. Usually, when the values entered in the program are exceeded, the supply of the active substance begins and along with this an alarm is triggered. Moreover, there are different approaches to the controls of such systems. For example, sprinkler models are fully automated, but there are other systems that provide for manual control. So, a fire extinguishing agent in gas fire extinguishing installations can be released both automatically and at the command of an operator through a control panel. But such a control system already depends on the type of installation itself - modular ones are oriented towards greater autonomy, while centralized ones allow the maximum range of management approaches.
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 sources of ignition by primary tools is impossible. Also, at some production facilities, personnel do not operate security systems around the clock. Obviously, in such situations, you can not do without an automatic means of fighting fire. Another thing is that to minimize risks, you should initially make the right choice of extinguishing agent, the automatic supply of which as a maximum will entail only planned and pre-calculated damage.
Fire extinguishing agent classification
For each type of fire extinguishing installation, a specific type of active substance is used. For safety reasons, the use of several materials in one complex is rarely practiced. The most common system is a water extinguishing design. Especially common are deluge complexes that 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 site. Fire damping systems include pumping equipment, control panels, pipelines, water tanks, warning devices, etc.
The second most popular substance used in deluge constructions is foam. Such systems are used to protect local areas in industrial premises, to prevent ignition of transformers and electrical devices. Sprinkler systems with foam extinguishing material are also quite widely used. By the way, such units have much in common with water installations, with the exception of special approaches to dosing. These are the main fire extinguishing substances used in stationary and mobile means of combating fires, but there are also specialized gas systems, powder and aerosol. As a rule, fire protection equipment with such fillers is used in special conditions - for example, in places where increased requirements are imposed on the content of electrical equipment.
Conclusion
With all the variety of substances used in modern fire extinguishing systems, experts still cannot name the universal and most effective way of fighting fire. There is a fairly clear segmentation of materials into classes, depending on their technical and operational qualities. At the same time, an important role is played by the effect of extinguishing substances on humans and objects that are in the ignition zone. For example, fire 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 middle-class fires.
But the problem lies in the consequences that the use of chemically hazardous substances entails. For this reason, technologists are mastering new fire extinguishing methods, including structural ones. An effective fire extinguishing substance can reach its full potential only in the only case if the system of combating the foci of ignition was properly organized. And in this regard, it is worth noting the importance of both the basic installations that supply the extinguishing material, and the control methods - automatic or manual.