Foam and wetting solutions are widely used to extinguish all types of fires. Their use makes it possible to reduce the consumption of fire extinguishing agent, reduce extinguishing time and reduce losses from fire. To obtain foam and wetting solutions, foaming agents are used, which are concentrated aqueous solutions of surfactants (surfactants) and other stabilizers. Foam was first obtained at the beginning of the last century as a result of a chemical reaction between soda and aluminum sulfate. The released carbon dioxide formed a bubble system, the stabilizer of such a foamed structure was “soap root”, and then licorice root extract - the so-called natural surfactants.

One of the most common and effective methods of fighting fires is extinguishing them using fire foam.

How does fire foam extinguish? Fire foam is air bubbles separated by partitions of water, which contains a foam stabilizer - a surfactant-based foaming agent. It is known that for a fire to occur, the following are needed: a flammable substance, an air oxidizer, the desired combination of their concentrations and ignition temperature. Combustion is a chemical process between fuel vapor and air oxidizer. To extinguish a fire, you need to isolate fuel vapors from the air oxidizer and/or reduce the temperature of the fuel below the ignition (flash) temperature. Firefighting foam provides these properties and functions.

In water-foam fire extinguishing technology, foaming agents (foam concentrates) serve as the initial component for obtaining a working solution of a foaming agent by diluting it with water to the required working concentration. The working solution of the foaming agent is supplied under pressure to various foam-generating devices (foam generators), in which a foam jet is formed due to the processes of atomization and ejection of ambient air. Aqueous working solutions of foaming agents and wetting agents are widely used when extinguishing fires using sprinklers, as well as on fire-fighting aircraft.

Wetting agents and foaming agents are divided into:

1. WA – synthetic foaming agents that do not contain fluorinated surfactants, used for extinguishing fires as wetting agents;
2. S – synthetic foaming agents that do not contain fluorinated surfactants;
3. S/AR – synthetic alcohol-resistant foam concentrates for special purposes without fluorinated surfactants for extinguishing water-soluble and water-insoluble flammable liquids;
4. AFFF – synthetic fluorine-containing film-forming foam concentrates for the purpose of extinguishing flammable liquids;
5. AFFF/AR - synthetic fluorine-containing film-forming, alcohol-resistant foaming agents for special purpose for extinguishing water-soluble and water-insoluble flammable liquids;
6. AFFF/AR-LV - synthetic fluorine-containing film-forming alcohol-resistant foaming agents of low viscosity for extinguishing water-soluble and water-insoluble flammable liquids;
7. FP – protein fluorine-containing foam concentrates intended for extinguishing flammable liquids;
8. FP/AR – protein fluorine-containing alcohol-resistant foam concentrates for the purpose of extinguishing water-soluble and water-insoluble flammable liquids;
9. FFFP - protein fluorine-containing film-forming foaming agents for special purpose for extinguishing flammable liquids;
10. FFFP/AR - protein fluorine-containing film-forming, alcohol-resistant foaming agents for special purpose for extinguishing water-soluble and water-insoluble flammable liquids.

One of the important areas of application of foaming agents is the production of wetting agents. These are solutions of surfactants in water, which, by reducing the coefficient of surface tension of water, allow it to better penetrate flammable solids and fibrous substances. Wetting agents penetrate into deep layers of materials as combustion objects, effectively cool and wet them due to a higher rate of impregnation and spreading than water. Due to the fact that wetting agents are able to saturate burning surfaces deeper, they eliminate hot spots of smoldering and smoke formation where water is less effective.

Wetting agents are classified as type WA, but general purpose foaming agents type S can be used as wetting agents.

Wetting agents are most widely used for extinguishing forest and peat fires. In those places where there is a high risk of forest and/or peat fires, in areas with arid climates or where there is a shortage of water to fight forest and peat fires - there are no large rivers, lakes or fire reservoirs - there must be reservoirs with ready wetting solutions.

For the production of wetting agents, hydrocarbon synthetic foaming agents of types WA and S are used.

Foaming agents (foam concentrates) of type S are products with a wide range of applications, used to combat fires of solid, liquid and fibrous combustible substances and materials. Suitable for both the production of fire foam and the production of wetting agents. They have high foaming ability.

Foaming agents type WA are exclusively suitable for the production of wetting agents. They have a low foaming ability, but their working solution has a high wetting ability, easily penetrates into porous materials and is especially suitable for extinguishing wood, cotton, peat, and straw.

If your occupation is related to forestry, fire control services or emergency services, you understand exactly how necessary fire extinguishing agents, wetting agents, foam concentrates, special equipment and inventory are. The lack or absence of these funds in areas of high fire risk can lead to catastrophic consequences. Therefore, it is necessary to carefully monitor the availability and timely replenishment of foaming concentrates, the serviceability of equipment, as well as the practical and theoretical training of those responsible for fire safety and fire extinguishing.

Forest fires annually destroy thousands of hectares of forest around the world; once a fire has spread over large areas, it is very difficult to stop. Therefore, it is necessary to organize and maintain a system for early detection of forest fires and prompt extinguishing of outbreaks. But if it was not possible to notice and extinguish the fire in time, then fire-fighting equipment is widely used to localize and eliminate fires - from hand-held sprayers that knock down the flames to firefighting aircraft.

In any of the above cases, the greatest extinguishing effect will be provided by the use of fire foam and wetting solutions. Therefore, it is necessary to purchase wetting agents and foaming agents for extinguishing forest fires in advance. You can buy them from our company.

Wetting is important in industry and everyday life. Good wetting is necessary when dyeing and washing, processing photographic materials, applying paint and varnish coatings, etc.

The cleaning properties of soap and synthetic powders are explained by the fact that the soap solution has lower surface tension than water. The high surface tension of water prevents it from penetrating into the spaces between the fibers of the fabric and into small pores.

One more circumstance is significant. Soap molecules have an oblong shape. One of the ends has an “affinity” for water and is immersed in water. The other end is repelled by the water and attaches to the fat molecules. Water molecules envelop fat particles and help wash them out.

Bonding wood, leather, rubber and other materials is also an example of the use of wetting properties. Soldering is also associated with wetting and non-wetting properties. In order for molten solder (for example, an alloy of tin and lead) to spread well over the surfaces of the metal objects being soldered and stick to them, these surfaces must be thoroughly cleaned of grease, dust, and oxides. Tin solder can be used to solder parts made of copper and brass. But aluminum is not wetted by tin solder. For soldering aluminum products, a special solder consisting of aluminum and silicon is used.

An important example of the application of the phenomenon of wetting and non-wetting is the flotation process of ore beneficiation. For this purpose, the ore is crushed so that pieces of valuable rock lose contact with unnecessary impurities. Then the resulting powder is shaken in water, to which oily substances are added. The oil envelops (wet) the valuable rock, but does not stick to impurities (does not wet them). Air is blown into the resulting suspension. Air bubbles stick to pieces of valuable rock that are not wetted by water (due to coating with an oil film). This happens because a thin layer of water between the air bubbles and the oil film enveloping the valuable rock, tending to reduce its surface, exposes the surface of the oil film (just as water on a greasy surface collects in drops, exposing this surface). Grains of valuable rock, together with air bubbles adhered to them, rise upward under the influence of Archimedean force, while unnecessary impurities settle to the bottom (Fig. 7.20).

Water wets the surfaces of some solids (sticks to them) and does not wet the surfaces of others. These properties of water determine many useful and simply curious phenomena.

§ 7.6. Pressure under a curved fluid surface

With its tendency to contract, the surface film creates additional pressure. The pressure that always exists inside a liquid increases when its surface is convex and decreases under a concave surface.

The effect of surface curvature on the pressure inside a liquid

The existence of this influence can be verified by simple experiment. Take a glass funnel with a tube bent at a right angle. Let's point the end of the funnel with the blown soap bubble at the candle flame (Fig. 7.21). We will notice that the candle flame is deflected. This indicates that air is flowing out of the funnel, which means that the air pressure in the bubble is greater than atmospheric pressure.

This kind of experience is also interesting. Let's connect a wide vessel A using a rubber tube with a narrow glass tube. Let's fill these communicating vessels with water. First install the end of the tube IN at the level of liquid in the vessel A. In this case, the surface of the water in the tube IN, as in vessel A, it is flat (Fig. 7.22, a). Since the water in both vessels is at the same horizontal level, the pressure directly below the flat surface of the liquid in both vessels is the same and equal to atmospheric pressure.

Let's slowly lower the phone IN. We will notice that the surface of the water in it has acquired a convex spherical shape (Fig. 7.22, b). Now the water is in vessel A and the tube IN is not on the same level. Water pressure in the vessel A at the end of the tube IN more than the atmospheric value ρgh, where ρ is the density of water, h - difference in water levels in vessels A And IN. Since liquid in communicating vessels A And IN is in equilibrium, then at the end IN directly below the convex surface the pressure is also greater than atmospheric pressure.

Let's continue the experiment, carefully lowering the tube IN lower. As a result, the curvature of the water surface in the tube IN will increase (the radius of the spherical surface of the water will decrease). The difference in water levels in the vessel will also increase A and handset IN. This means that the smaller the radius of curvature of this surface, the greater the additional pressure under the convex surface of the liquid.

If the end of the tube IN raise above the water level in the vessel A(Fig. 7.22, V), then the surface of the water in the tube IN will become concave (water wets the glass) and the water level in the tube IN will be higher than the water level in vessel A. This means that under the curved (concave) surface of the water in the tube IN pressure is less than atmospheric.

This leads to the following conclusion: the pressure directly below a convex surface of a fluid is greater than the pressure below a flat surface of a fluid, and the pressure below a concave surface of a fluid is less than the pressure below a flat surface.

Wetting agents (auxiliary substances) OP-7 and OP-10

is a light oil-like liquid or paste. The color of the wetting agent varies from light yellow to light brown. Wetting agents are nonionic surfactants (surfactants). Wetting agents are highly soluble in water, have a low odor and a slightly alkaline reaction. Wetting agents are obtained by treating mono- and dialkylphenols with ethylene oxide.

Chemical formula: O(CH 2 -CH 2 -O)nCH 2 -CH 2 -OH.
n=7-9 (for substance OP-7) and 10-12 (for substance OP-10).

Application of wetting agents OP-7 and OP-10.
They are used as wetting and emulsifying surfactants in a variety of technological processes. Wetting agents are included in TMS preparations and herbicides. They have found their application in oil production, oil refining, chemical, textile and other industries. One advantage of surfactants is that they are easily treated biologically in wastewater.

Physico-chemical parameters of wetting agents (auxiliary substances) OP-7 and OP-10 GOST 8433-81:

Indicator name	Norm for a substance
	OP-7	OP-10
Appearance	Light yellow to light brown oil-like liquid or paste
Appearance of an aqueous solution with a concentration of 10 g/l	Clear or slightly cloudy liquid	Clear liquid
Mass fraction of the main substance, %, not less	88	80
Mass fraction of water, %, no more	0,3	0,3
The indicator of the concentration of hydrogen ions (pH) of an aqueous solution with a concentration of 10 g/l	6-8	6-8
Temperature limits for the brightening of an aqueous solution, ° C substances OP-7 concentration 20 g/l substances OP-10 concentration 10 g/l	55-65 -	- 80-90
Surface tension of an aqueous solution with a concentration of 5 g/l, nm, no more	0,035	0,037

Safety requirements for wetting agents (auxiliary substances) OP-7 and OP-10 GOST 8433-81:

Hazard Class	3
Basic properties and types of hazard
Basic properties	Oil-like liquids or pastes from light yellow to light brown in color, have a slightly alkaline or slightly acidic reaction, and are highly soluble in water.
Explosion and fire hazard	Auxiliary substances OP-7 and OP-10 are fire hazardous. They ignite from an open flame when heated.
Danger to humans	Harmful if swallowed. Causes skin and eye irritation. They have an allergenic effect. Contact with skin causes contact dermatitis. If it gets into the eyes, conjunctivitis develops.
Individual protection means	Overalls, safety glasses, robe or cotton suit, rubber gloves or canvas mittens, rubberized apron, rubber boots, filter gas mask.
Necessary actions in emergency situations
General	Remove strangers. Isolate the hazardous area. Wear protective clothing. Eliminate all sources of fire and sparks. Observe fire safety measures. Provide first aid to the victims.
In case of leakage, spillage and scattering	Stop the leak if it is not dangerous. Wash off small leaks with plenty of water. Protect large leaks with an earthen berm, pump out the product into a container, and fill the remainder with plenty of water.
In case of fire	Wear protective clothing. To extinguish, use finely sprayed water, dry powders or gas compositions. Supplying ordinary foam or room water can lead to foaming of the burning liquid, overflowing the side of the container and increasing the combustion area.
Neutralization
First aid measures	Fresh air, peace. Rinse eyes and mucous membranes with plenty of running water. In case of contact with skin, rinse with plenty of water for at least 15 minutes.

Packaging, transportation and storage
Wetting agents OP-7 and OP-10 are packaged in steel barrels with a capacity of 100-300 liters and steel railway tanks.
Transportation of wetting agents is carried out mainly by rail and road transport, but transportation by other modes of transport is also possible. When transporting by rail, steel railway tanks are used. When transporting by road, standard factory packaging or special steel tanks are used.
Wetting agents OP-7 and OP-10 are stored in covered warehouses in hermetically sealed steel containers.
The guaranteed shelf life of the product is 1 year from the date of manufacture.

Question No. 1. Basics of foam extinguishing: foams, foaming agents, wetting agents, their purpose, types, composition, physicochemical properties and scope of application. Safety precautions when working with foaming agents.

Types of foam, their composition, physicochemical and fire extinguishing properties,

procedure for obtaining and scope of application.

Foam - a dispersed system consisting of cells - air (gas) bubbles, separated by films of liquid containing a foam stabilizer.

Types of foam by production method:

- chemical foam– obtained as a result of a chemical reaction of alkaline and chemical components (the released carbon dioxide foams an aqueous alkaline solution);

- air-mechanical foam– obtained by mechanical mixing of the foaming solution with air.

Physico-chemical properties of foam:

- sustainability– the ability of foam to maintain its original properties (resist destruction for a certain time);

- multiplicity- the ratio of the volume of foam to the volume of the foaming agent solution contained in the foam;

- viscosity- the ability of foam to spread over the surface;

- dispersion- degree of grinding of bubbles (size of bubbles);

Foam concentrates for extinguishing fires with low expansion foam (foam expansion from 4 to 20);

Foaming agents for extinguishing fires with medium expansion foam (foam expansion from 21 to 200);

Foam concentrates for extinguishing fires with high-expansion foam (foam expansion more than 200).

Foaming agents, depending on their applicability for extinguishing fires of various classes according to GOST 27331, are divided into:

Foaming agents for extinguishing class A fires;

Foaming agents for extinguishing class B fires.

Foaming agents, depending on the possibility of using water with different contents of inorganic salts, are divided into types:

Foaming agents for producing fire extinguishing foam using drinking water;

Foaming agents for producing fire extinguishing foam using hard water;

Foaming agents for producing fire extinguishing foam using sea water.

Foaming agents, depending on their ability to decompose under the influence of microflora of water bodies and soils according to GOST R 50595, are divided into: rapidly degradable, moderately degradable, slowly degradable, extremely slowly degradable.

Classes of foam concentrates for extinguishing fires based on a set of purpose indicators:

1 - film-forming foaming agents intended for extinguishing fires of water-insoluble flammable liquids by supplying low expansion foam to the surface and into the oil product layer;

2 - foam concentrates intended for extinguishing fires of water-insoluble flammable liquids by soft supply of low expansion foam;

3 - special-purpose foam concentrates intended for extinguishing fires of water-insoluble flammable liquids by supplying medium expansion foam;

4 - general purpose foam concentrates intended for extinguishing fires of water-insoluble flammable liquids with medium expansion foam and extinguishing fires of solid combustible materials with low expansion foam and an aqueous solution of a wetting agent;

5 - foam concentrates intended for extinguishing fires of water-insoluble flammable liquids by supplying high expansion foam;

6 - foam concentrates intended for extinguishing fires of water-insoluble and water-soluble flammable liquids.

Foaming agents have a symbol indicating:

Foaming agent class;

Type of foaming agent;

The concentration of the foaming agent in the working solution;

Chemical nature of the foaming agent.

Foaming agents of classes 1, 2, 3, 4, 5 and 6 in the symbolic designation have the index 1H, 2H, 3C, 4C, 5B and 6, respectively.

Foam concentrates of classes 1 and 2, which form fire-extinguishing foam of medium and high expansion, in the symbol designation have the index 1NSV and 2NSV, respectively.

Foaming agents of classes 1 and 2, which form fire extinguishing foam of medium expansion, in the symbol designation have the index 1NS and 2NS, respectively.

Foam concentrates of class 1 and 2, which form high-expansion fire extinguishing foam, are designated as 1НВ and 2НВ, respectively.

Foam concentrates of class 3, which form fire extinguishing foam of high expansion, have the index 3SV in the symbol.

If a foam concentrate of class 6 is able to form fire extinguishing foam of low, medium and high expansion, its symbol designation indicates the corresponding index H, C, B. The absence of a corresponding index means that the foam concentrate is not recommended to be used to extinguish fires with foam of this expansion.

When the manufacturer recommends using a foam agent of class 6 when extinguishing water-insoluble and water-soluble flammable liquids with different concentrations, its symbol indicates the concentration of the foam agent in the working solution when extinguishing water-insoluble and water-soluble flammable liquids.

An example of a symbol for a foam concentrate 2 NSV- 6 fs

Checking the quality of foaming agents and determining the foam expansion ratio.

To determine the foam expansion ratio, a 2-6% solution of foaming agent is poured into a glass graduated cylinder with a capacity of 1000 cm3, closed with a stopper and, holding it in a horizontal position with both hands, shaken in the direction of the longitudinal axis for 30 s. After shaking, the cylinder is placed on the table, the stopper is removed and the volume of foam formed is measured. The ratio of the resulting volume of foam to the volume of solution expresses the foam multiplicity. Sustainability foam depends on the time during which the foam obtained using the method of determining the expansion ratio is destroyed by 2/5 of the original volume.

The quality indicators of foam concentrates when stored in fire departments and at protected facilities equipped with fire extinguishing systems are checked after the expiration of the warranty period, and then at least once every 6 months (PO-3NP, Foretol, “Universal” - at least once every 12 months). The analysis of indicators is carried out in accredited organizations in accordance with GOST R “Foaming agents for extinguishing fires. General technical requirements and test methods". A decrease in the value of indicators below the established standards by 20% is the basis for write-off or regeneration (restoration of the original properties) of the foam concentrate.

Use of foaming agents.

Recently, the following foam concentrates have been used to produce fire-extinguishing air-mechanical foams.

Foaming agents for general use.

PO-6K- an aqueous solution of sodium salts of sulfonic acids (28...34%), obtained by neutralizing acid tar with a solution of soda ash, sodium sulfate (5%) and non-sulfonated hydrocarbons (1%). Use a 6% aqueous solution. Non-biodegradable. High-frequency MP of low and medium expansion is obtained from the solution.

PO-ZAI– synthetic, biodegradable. Its working solutions do not have an irritating or cumulative effect on the human body. The concentration of the solution to obtain foam is 3%.

TEAS– synthetic, biodegradable. Designed to produce fire extinguishing foam of low, medium and high expansion.

PO-3NP

PO-6TS- synthetic, biodegradable. Designed to produce fire extinguishing foam of low, medium and high expansion.

PO-6OST- synthetic, biodegradable. Available in two modifications (grade 1 and 2), which differ in pour point: - 3 and - 20 g. C. Designed to produce fire extinguishing foam of low and medium expansion, as well as to produce a wetting solution for extinguishing class A fires.

Foaming agents for targeted use.

TEAS-NT- synthetic, biodegradable. Designed to produce fire extinguishing foam of low and medium expansion at low temperatures.

PO-6NP- synthetic, biodegradable. Designed for extinguishing fires of petroleum products, gas liquids, for use with sea water.

"Morpen"- synthetic, biodegradable. Designed to produce fire extinguishing foam of low, medium and high expansion using both fresh and sea water.

PO-6MT- synthetic, frost-resistant, biodegradable. Designed to produce fire extinguishing foam of low, medium and high expansion.

PO-6TsVU- synthetic, highly resistant, biodegradable. Designed to produce fire extinguishing foam of low and medium expansion. Recommended for extinguishing fires at airports, for covering runways during emergency landings of aircraft.

PO-6A3F– fluorosynthetic, film-forming (forms an aqueous film on the burning surface).

Petrofilm-RNN– consists of a foaming protein base, surface-active organofluorine compounds with olephobic and film-forming properties. Designed for extinguishing class A and B fires with low expansion foam (including the sub-layer method). Non-toxic, biodegradable.

Tridol-RNN– consists of a foam-forming synthetic base, surface-active organofluorine compounds with olephobic and film-forming properties. Designed for extinguishing class A and B fires with low expansion foam (including the sub-layer method). Non-toxic, biodegradable.

Wetting agents.

Wetting agent aqueous solution- a foaming agent solution intended for extinguishing fires of solid combustible materials.

The use of wetting solutions makes it possible to reduce water consumption by 35-50% and significantly increases the effect of water use. It penetrates faster and easier into a mass of burning substances or wets a large area.

Safety precautions when working with foaming agents.

paragraph 238 POTRO. When refueling a fire truck with foaming agent, the personnel of the fire service unit must be provided with safety glasses (eye protection shields). Mittens and waterproof clothing are used to protect the skin. The foaming agent is washed off from the skin and mucous membrane of the eyes with clean water or saline solution (2% boric acid solution). Refilling fire trucks with powder and foaming agent must be mechanized. If mechanized refueling is not possible, in exceptional cases, fire trucks may be refueled manually. In the case of manual refueling of fire trucks, it is necessary to use measuring containers, hanging (removable) ladders or special mobile platforms. The procedure for filling a car with powder and loading a tank using a vacuum installation and manually is determined by the relevant instructions.

Conclusion: Foam is a dispersed system consisting of cells - air (gas) bubbles, separated by films of liquid containing a foam stabilizer. The foam is intended for extinguishing fires of solid (class A fires) and liquid substances (class B fires) that do not interact with water, and primarily for extinguishing fires of oil products. To obtain air-mechanical foam or wetting solutions using firefighting equipment, foam concentrates are used.

Question No. 2. Instruments and apparatus for foam extinguishing: foam mixers, dosing inserts, air-foam barrels, foam generators, foam draining devices. Purpose, device, technical characteristics, operation and safety measures during operation.

Foam mixers.

Foam mixers are designed to produce an aqueous solution of a foaming agent used to form foam in medium expansion foam generators. Foam mixers are jet pumps

PS-5 foam mixers are installed on fire pumps. The PS-5 dispenser has 5 radial holes with diameters of 7.4; eleven; 14.1;18.2; 27.1 mm, designed for the dosage of foaming agent when operating 1, 2, 3, 4, 5 GPS-600 generators or SVP trunks, respectively.

Currently, the industry produces portable foam mixers PS-1, PS-2, which are similar in design and differ only in size and technical characteristics.

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The foam mixer is tested for the strength of the material and the tightness of the connections using a hydraulic pressure of 1.5 MPa (15 kgf/cm2), and water infiltration for 1 minute is not allowed.

The dosage of the foam mixer is checked with water at a pressure in front of the foam mixer of 0.7 MPa (7 kgf/cm2) and a head of 0.45 MPa (4.5 kgf/cm2). Water suction is determined using a measuring container. It must be within the limits indicated in the table, and the resulting flow rate of sucked water is multiplied by 0.86 - the coefficient of the difference in viscosity of water and foaming agent PO-1 (when using other types of foaming agents, the coefficient may be different, which must be determined by calculation).

For normal operation, the container with foam concentrates should be at the level of the mixer or slightly higher (but not exceed a height of 2 m).

INDICATORS	FOAM MIXERS
PS - 1	PS - 2
Pressure in front of the foam mixer, MPa
Pressure behind the foam mixer, MPa	0.45…0.70 (not less)
Consumption of foam solution, l/s
The amount of sucked foaming agent at a pressure in front of the mixer is 0.8 MPa, l/s
Foaming agent dosage PO-1, %	4…6 (unregulated)
Conditional passage of the suction hose, mm
Conditional bore of connecting heads, mm
Operating temperature range, ° C
Weight, kg	version 1	3.6 (no more)	5.0 (no more)
version 2	9.0 (no more)	10.0 (no more)
Length, mm	version 1	395 (no more)	480 (no more)
version 2	355 (no more)	440 (no more)
Service life, years	8 (at least)

Dosing inserts.

Dosing inserts are designed to introduce a foam concentrate into the water flow from the tank of a foam fire extinguishing vehicle. Dosing inserts are most often installed in pressure hose lines in cases where it is necessary to provide high flow rates of the foaming solution, for example, to power foam lifters with 2 - 3 GPS-600 foam generators or one GPS-2000.

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where Q is the foam concentrate consumption, m cubic/s; m - flow coefficient, g - acceleration of gravity, m/s sq., D H - pressure difference in the hose line with foam concentrate and water, m (D H = Hp - Hb).

When supplying a foam agent to the dosing insert, the pump supplying the foam agent must create a pressure of 2 to 30 m (depending on the number of connected foam generators) and must always be higher than the pressure in the hose line.

Dosing inserts can also be installed on the suction line. In this case they must be equipped with appropriate connection heads.

The barrels are air-foam.

Air-foam nozzles are designed to produce low-expansion air-mechanical foam (up to 20) from an aqueous solution of a foaming agent and supply it to the fire.

Fireman's manual trunks SVPE and SVP have the same design, they differ only in size, as well as an ejection device designed to suck in foam concentrate directly from the trunk from a backpack tank or other container.

https://pandia.ru/text/78/010/images/image008_111.gif" alt=" Signature:" align="left" width="242" height="146">.gif" align="left" width="371" height="316"> Пеногенератор состоит из распылителя !} 1 , housing 2 with guide device 4 and a package of meshes 3 . The principle of operation of GPS generators: a 6% foam-forming solution is supplied through hoses to the foam generator sprayer, in which the flow is crushed into individual droplets. Conglomerate of solution droplets moving from sprayer To grid sucks air from the external environment into housing diffuser generator A mixture of droplets of foaming solution and air falls on mesh package. On grids, deformed drops form a system of stretched films, which, enclosed in limited volumes, form first elementary (individual bubbles) and then mass foam. The energy of the newly arriving droplets and air forces the mass of foam out of the foam generator.

During operation, special attention is paid to the condition of the mesh package, protecting them from corrosion and mechanical damage.

GPS foam generators are most often used as hand-held nozzles, but in some cases they are installed permanently. Airfield fire trucks are equipped not only with manual GPS generators, but also with stationary ones installed in the under-bumper spaces to create a foam strip in front of and behind the fire truck. Foam generators are permanently installed in foam chambers of tanks with flammable liquids, as well as in some automatic fire extinguishing installations.

Foam drainage devices.

Foam draining devices are designed to extinguish fires of liquids in tanks. They are divided into stationary and mobile.

Stationary foam drainage devices include a foam drainage chamber and a stationary air-mechanical foam generator.

https://pandia.ru/text/78/010/images/image013_71.gif" align="left" width="203" height="370"> There is a retractable inner pipe in the outer pipe. For tightness, a seal is installed between the pipes . Two pipes are welded to the outer pipe for connecting pressure hose lines. Attached to the upper part of the outer pipe are brackets for guy wires and a bracket on which a roller with a roller for the extension mechanism is mounted. The lower unit consists of a shaft with a drum and a lock. The shaft is equipped with handles on both sides for drive.Two cables are wound on the drum: one is designed to extend, the other to move the inner pipe.Using the lock on the drum, you can install the lift at the desired height.

At the top of the inner tube there is a threaded coupling for attaching an extension, which is a piece of pipe with two nuts designed to attach to the inner tube and manifold. The comb consists of vertical and horizontal pipes. The horizontal pipe has two pipes with connecting heads for connecting GPS-600. The modernized telescopic lift-foam drain is delivered to the fire site by vehicles and assembled on site in a horizontal position.

The foaming solution is supplied to the foam drain from fire pumps. Air-mechanical foam comes from 2 GPS-600.

Malfunctions of telescopic foam lifts include distortion of the inner pipe in the gland or coupling. A faulty oil seal must be replaced. After work, the foam drain is washed with water and all rollers, rollers and the drum of the lifting mechanism are re-lubricated. After work, generators are inspected, damaged grids or housing are repaired. Dents on the body are smoothed out. Before being placed in a combat crew, cables and guy wires are tested for strength in accordance with the manufacturer’s passport.

Combined fire monitor barrel PLS-60KS (fig.) is designed to create and direct a stream of water or air-mechanical foam when extinguishing fires and is included in the fire truck kit. It is manufactured according to the “pipe-in-pipe” scheme and consists of a receiving body with a flange 12 and connecting nut, barrel 5, water nozzle 2 and casing 1 ..jpg" align="left" width="387 height=198" height="198">

Rice. . Stationary fire monitor combined

1 – casing; 2 - nozzles; 3 - pipe;

4 - fixing device;

5 - flange; 6, 8 - handles;

7 - spool; 9 - pipe

The principle of operation of the barrel is as follows. Along the trunk 5, ending in a nozzle with an internal outlet with a diameter of 28 mm, a compact stream of water or a wetting agent solution is supplied. In this case, the handle in the pipe should be in position B (water). When switching the handle to position P (foam), the switch holes are blocked 8, and the supplied foaming agent solution, passing through the side holes in the pipe, sucks in air. In the annular space between the trunk 5 and casing 1 forms air-mechanical foam, which is supplied to the fire.

The barrel is controlled by a person using a handle, which is fixed by a valve in a position convenient for work. All rotary joints are sealed with rubber rings.

A four-bladed damper is installed inside barrel 5. There is a special handle to switch the barrel.

Stability under the action of the reactive force that occurs when water is supplied and tends to overturn the trunk is ensured by a support consisting of a removable carriage, which consists of two symmetrically curved legs with spikes.

The stationary barrel SPLK-20S (Fig.) is a modification of the portable monitor barrel SPLK-20P and differs from it in the absence of a receiving body and support (carriage). The barrel is installed permanently (usually on the cabins of fire tankers) and is used to create and direct a stream of water or air-mechanical foam when extinguishing fires.

The operating principle of fire monitors PLS-40S and PLS-60S is similar to the operation of the SPLK-20S fire monitor.

Fire monitors PLS-40S, PLS-60S (Fig.) consist of a tee 11 , flange 12 for connection to a water source, branching 10, sprayer 6, barrel for forming a water jet 5 with nozzle 2, barrel for producing air-mechanical foam 1 , rectifier 4 and sedative 3, barrel-mounted switching device 8 and control levers 7 . Branching 10 hinged on the receiving body, which is connected to the support flange. At a fork 10 and tee 11 strengthened barrel locking mechanism 9.

Tactical and technical indicators of foam supply devices.

foam supply device	Pressure at the device, m	Solution concentration, %	Consumption, l/s	Foam ratio	Foam capacity, m cubic/min (l/s)	Foam supply range, m
		PO solution
SVP-2 (SVPE-2)
SVP-4 (SVPE-4)
SVP-8 (SVPE-8)

As mentioned above, the use of wetting agents significantly improves the fire extinguishing properties of water and reduces extinguishing time. Using surfactant solutions, fire departments seem to double the volume of water delivered to fires. Reducing the extinguishing Bpv prevents the formation of large and protracted fires and significantly reduces fire losses.

The organization of the use of wetting agents by garrison fire departments should be handled by service and training departments (departments) together with fire-technical stations. The surfactants mentioned above are produced by industry and fire departments are routinely supplied with them or purchased from enterprises that use them in technological processes.

Currently, wetting agents are used in large quantities in textile enterprises, plants and factories involved in cleaning hard surfaces, flotation and beneficiation of ores, degreasing and tanning leather, dyeing furs, preparing emulsions, pesticides, as well as in enterprises producing varnishes and paints, paper , synthetic fibers and films, synthetic rubbers and other polymers. Wetting agents are widely used in the petroleum and chemical industries.

Almost all of the surfactants under consideration are liquids with varying viscosities; only sulfonol NP-1, the wetting agent NB and sulfonate of some brands are solids with varying degrees of solubility. Sulfonol NP-1 should be prepared only in the form of a solution of working concentration. From the wetting agent NB and sulfonate you can obtain concentrated solutions, which can then be sucked into water either by portable ejectors or by fire truck mixers. Emulsifier OP-4, auxiliary substance OP-7, wetting agent DB are viscous liquids. They are pre-diluted with water and then mixed into the water. The remaining substances are liquids , mix well with water. They are easily sucked up by jetting devices. Surfactants, with the exception of OP-4, OP-7 and the wetting agent DB, in concentrations exceeding the optimal ones, when supplied from barrels type! GVP can form foam of increased expansion, and OG1 4, OP-7 and DB are low-expansion foam. Therefore, they can be exported in concentrated form in non-draining barrels or in fire truck tanks. to and

If you use the stationary air-foam mixer available on the main fire trucks to prepare the working solution, then the concentration of the wetting agent in the solutions taken out to the fire can be 25-50 times higher than the working one. Such a wide range of concentrations is explained by the different solubility of wetting agents, the viscosity of concentrated solutions and the ability of the mixer to suck up different amounts of solution.

To prepare a working solution in a fire using this method, it is necessary to first tar the mixer to supply a solution of optimal concentration through barrel B. From a foaming agent tank with a capacity of 150 liters, which is filled with a wetting agent that is highly soluble in water, for example, sodium sulfonate, you can get up to 7000 liters working solution.

To prepare concentrated solutions (over 10%), all pastes and most solid and liquid surfactants (OP-7, OP-10, DB) should be dissolved with stirring in warm (40-60 °C) water. If the dissolution time is unlimited, then the water is not heated, and the mixture is stirred for a long time until a solution is obtained.

However, when using a foam concentrate tank for transporting concentrated solutions of wetting agents, the possibility of using air-mechanical foam for extinguishing large quantities of flammable liquids in a fire is excluded. Although aqueous solutions of wetting agents, as well as foaming agent PO-1 and others, are capable! form air-mechanical foam, their fire extinguishing properties do not always meet the requirements. Therefore, in fire departments in the exit area of ​​which there are oil depots or facilities where flammable liquids are used, foam agent should be removed to fires. In fire departments serving facilities for the processing or production of fibrous materials, it is advisable to deliver a concentrated wetting solution in tank trucks. Working solutions for almost all substances can be prepared directly in tanks.

Wetting solutions prepared for fires in tank trucks are used mainly for feeding the first barrel. Extinguishing practice shows that one tanker with a wetting solution is, as a rule, sufficient to eliminate an uninitiated fire and localize a developed one. Considering the high wetting ability of surfactant solutions, it is necessary to use only slotted hoses for their supply. When laying a hose line, it is necessary to provide a supply of it, since a wetting solution from one tanker can extinguish a fire area 2-2.5 times larger than with water, and therefore, linemen move considerable distances from the initial position.

All solid materials that can be extinguished with water can be extinguished with wetting solutions. A particularly high effect is observed when extinguishing cellulose materials (cotton, wood, fabrics, paper, etc.), which are the main combustible materials in fires in residential, administrative, medical, agricultural and other buildings. Therefore, fires in these buildings are extinguished with wetting solutions with a lower supply intensity and faster than with water. In this regard, it is recommended to use overlapping trunks with a spray diameter of no more than 13 mm. However, extinguishing practice shows that in order to reduce the wetting solution that is excessively spilled during fires, it is advisable to use trunks with a smaller spray diameter. When using barrels with a 13 mm spray, they must be blocked after quickly processing burning surfaces, during dismantling of burning materials, when stopping, while moving, or changing the positions of the barrels. Indoor fires should be extinguished with spray jets, since this reduces the intensity of the solution supply and lowers the temperature and smoke level in the burning room. Continuous jets extinguish fires when, due to the high temperature in the room, it is impossible to get close to the burning object. The jets must be quickly moved to the burning surface, trying to process it as quickly as possible.

When processing cellulose materials with a solution, a small area of ​​smoldering may remain. In this case, the solution should not be applied to it, since it will go out when the solution penetrates. The intensity of supply p.-icrnopn smlknnl ii.i extinguishing with cellulose material (wood, fabric, paper, hay, etc.) can be taken equal to 0.03-0.05 l/(m 2 -s), i.e. .more than 2 pa i.i less than for the pod. Cotton, hemp, soot and other similar substances cannot be extinguished with water; cotton must be disassembled and spilled with water. For these substances, the intensity of supply of surfactant solutions (based on the results of extinguishing fires) should be taken as 0.05-0.07 l/(m 2 -s), and if the surfactant concentration for extinguishing cellulose materials can be optimal, determined in laboratory conditions, then for fibrous materials it should be increased by 1.3-2 times.