Fire is a disaster that has plagued humanity throughout its existence. For all the centuries of struggle with it, it was found that the best and most affordable remedy for this disaster is water. Let's look at the features of tools working on the basis of this liquid, and also find out what class of fire can be extinguished with a water fire extinguisher.
"Burn, burn clearly, so as not to go out ..."
It is appropriate to say such a phrase when it comes to fire divorced for some purpose, which is under supervision. In contrast, fire is also the burning of something, but out of control, capable of causing or already causing damage to the property and lives of any living creatures.
To make it easier to deal with this dangerous phenomenon, as well as in order to clearly know which fire extinguisher to extinguish a fire, all existing varieties of the elements were divided into different types and classes. This was done on the basis of certain criteria that formed the basis of several classifications. Consider the two most famous of them.
Classification by localization
In this case, the determining criterion for a fire is the area or place where the active burning zone is located.
There are three main types:
- Industrial. This includes a fire in a warehouse, a fire in any production room in a factory or factory.
- Natural. This is the burning of the forest, steppe, peat, etc.
- Domestic. As the name implies, this is a fire in public buildings and residential buildings (schools, hospitals, theaters, supermarkets). This also includes the ignition of cultural sites.
A similar classification is needed when choosing extinguishing agents, and most importantly - their quantity. For example, domestic fires are smaller than natural fires, so they require the use of a smaller amount of fire extinguishing substance (OTV).
When localization of ignition of domestic and natural types is rarely necessary to deal with the burning of hazardous chemicals, metals or alkalis, as is the case with industrial. Therefore, it is enough to use the most common types of fire extinguishers (carbon dioxide, powder, water).
Fire classification by type of combustible material
However, the most important is the systematization of fires by the type of flaming substances. After all, the combustion temperature and other conditions of the course of this physicochemical process differ for different materials.
Classification of fires by type of combustible material implies naming each class in capital Latin letters. In different countries, they have some differences.
The following classes are characteristic of the Russian Federation:
- A - burning wood (and products from it), coal, textiles and other solid substances, accompanied by decay. The ignition of other solids (e.g. plastic) also belongs to this class.
- B - ignition of water-soluble (gasoline, ether, oil) and non-water-soluble liquids (ethanol, methanol, glycerin), as well as solids in a liquefied state (paraffin).
- - combustion of gaseous substances ( 2 , ₃₈).
- D - ignition of light non-alkali metals, alkaline and similar substances (Na, K). Combustion of compounds containing metal.
- E - blaze of flammable compositions and materials in electrical installations under voltage.
- F - burning of radioactive substances and materials of all types and states of aggregation.
What fire extinguishers are used?
For each of the listed varieties of fires, a certain type of means is selected to combat it. Thus, first of all, such a classification is important for the fire brigade, which will choose the appropriate means according to the class of fire and the place of its localization.
In addition, the letter system helps in organizing fire safety. Knowing what exactly can catch fire at the enterprise or in a residential building, a certain type of fire extinguisher is selected for permanent storage there.
As a rule, on the label of each OT all classes are indicated with which it can cope. However, even without these tips, each type of fire extinguisher has its own specialization:
- Powder OTs cope with classes A, B, C, E. Among them there are also “truncated” versions capable of fighting only fires B, C, E.
- Foam fire extinguishers are of two types: chemical (OHP) and air-foam (ORP). Regardless of this, they both successfully fight classes A and B.
- HFC extinguishers (OX) cope with fires B and C. Sometimes they are used to combat fires of electrical equipment from class E, which OU can not cope with.
- Carbon dioxide is widely used for B and C classes. And also when extinguishing burning electrical appliances from class E (under voltage up to 1000 V).
Water extinguishers (OV)
Let us consider in more detail extinguishing agents of this type. Before you know what class of fire you can put out a water fire extinguisher, let's get acquainted with the features of this variety of OT.
As the name implies, the active substance inside this device is water. In addition to H 2 O, the composition contains one percent of synthetic additives.
They are used to improve the quenching properties of water. For example, fluoride compounds help to increase the wetting properties of H 2 O. And this helps to better cope with smoldering solids, which are beyond the power of other RTs (chladonic and carbon dioxide).
When using OM, the quenching occurs due to the ability of the liquid to quickly absorb heat, cooling the ignition area, and at the same time preventing the access of O 2 to it.
Unlike other types of fire extinguishers, water is less harmful to the environment and safe to use.
The main disadvantage is the relatively high (if you take into account the OS and OX) the freezing temperature of water (zero degrees). This fact does not allow the use of organic pollutants and even their storage in rooms with a low temperature (freezers in production facilities, rooms without heating in the winter).
Varieties
Before moving on to the main question of what class of fire can be extinguished with a water fire extinguisher, we will deal with the types of OM.
The parameter by which they are distinguished is the diameter of the jet supplied from the RT.
All data on methods of application and types of water fire extinguisher are always indicated on the label and in the OT passport.
Distinguish such:
- finely dispersed OBM (diameter of each drop from one hundred micrometers);
- finely dispersed OVR (diameter up to one hundred micrometers);
- compact jet HVAC.
What class of fire can I put out with a water fire extinguisher?
According to the current standards, the explosive agent is designed to combat class A fires. That is, to extinguish solids, capable and not capable of smoldering. Because of this, a water fire extinguisher is most popular for dealing with domestic fires.
The environmental friendliness and accessibility of the main active component of OT (water) makes such devices the most used for extinguishing forest fires, burning peat bogs and other natural-type fires. In this case, the penetrating properties of H 2 O play a special role. They help not only to cope with the source of the fire, but also with decay (especially important for peat).
Features of OM with additives
If chemical additives are included in addition to water, this type of fire extinguisher can also cope with category B fires. As a rule, this applies to fluorine-containing surfactants.
Moreover. the use of other types of additives reduces the freezing point of water in the fire extinguisher. This makes it possible to use it at low sub-zero temperatures. Please note that if the amount of additives contained exceeds 1% - the fire extinguisher already refers not to water, but to emulsion OT.
Today, much controversy is caused by the ability of water fire extinguishers to deal with category E fires. It is widely believed that OVR (finely dispersed) can extinguish electrical installations with voltages up to 1000 V. This is achieved due to the large distance between the water drops, due to which it ceases to be an electric conductor.
How close this statement is to the truth is not exactly known. Therefore, while there is no unambiguous expert opinion on this matter, it is better to use OM only to combat A and B fire classes.