Administrative buildings 1.0 ÷ 1.5

Libraries, book depositories, archives 0.5 ÷ 1.0

Woodworking enterprises:

Sawmills (buildings I, II, III fire resistance) 1.0 ÷ 3.0

The same (buildings IV and V degree of fire resistance 2.0 ÷ 5.0

Dryers 2.0 ÷ 2.5

Preparation shops 1.0 ÷ 1.5

Plywood production 0.8 ÷ 1.5

premises of other workshops 0.8 ÷ 1.0

Residential buildings 0.5 ÷ 0.8

Corridors and galleries 4.0 ÷ 5.0

Cable structures (cable burning). 0.8 ÷ 1.1

Forest areas (wind speed 7+ 10 m/s and humidity 40%):

Rada-pine forest sphagnum up to 1.4

Long moss and green moss spruce forest up to 4.2

Pine-green moss (berry) up to 14.2

Pine forest pine forest up to 18.0

vegetation, forest floor, undergrowth,

Tree stand during crown fires and wind speed, m/s:

8 ÷ 9 to 42

10 ÷ 12 to 83

the same along the edge on the flanks and in the rear at wind speed, m/s:

10 ÷ 12 8 ÷ 14

Museums and exhibitions 1.0 ÷ 1.5

Transport objects:

Garages, tram and trolleybus depots 0.5 ÷ 1.0

Repair halls of hangars 1.0 ÷ 1.5

Sea and river vessels:

Combustible superstructure in case of internal fire 1.2 ÷ 2.7

The same for outdoor fire 2.0 ÷ 6.0

Internal superstructure fires if available

synthetic finishes and open openings 1.0 ÷ 2.0

polyurethane foam

Textile industry enterprises:

premises textile production 0.5 ÷ 1.0

Also, if there is a layer of dust on the structures 1.0 ÷ 2.0

fibrous materials in a loosened state 7.0 ÷ 8.0

Combustible coatings of large areas (including hollow ones) 1.7 ÷ 3.2

Combustible structures of roofs and attics 1.5 ÷ 2.0

Peat in piles 0.8 ÷ 1.0

Flax fiber 3.0 ÷ 5.6

- textile products	0.3 ÷ 0.4
- paper rolls	0.3 ÷ 0.4
- rubber products (in the building)	0.4 ÷ 1.0
- rubber products (in stacks on
open area)	1.0 ÷ 1.2
- rubber	0.6 ÷ 1.0
- lumber:
- round wood in stacks	0.4 ÷ 1.0
lumber (boards) in stacks at humidity, %:
- up to 16	4,0
16 ÷ 18	2,3
- 18 ÷ 20	1.6
- 20 ÷ 30	1,2
- over 30	1.0
heaps of pulpwood at moisture content, %:
- up to 40	0.6 ÷1.0
over 40	0.15 ÷ 02
Drying departments of tanneries	1.5 ÷ 2.2
Rural settlements:
- residential area with dense development of buildings and V degree
fire resistance, dry weather and strong wind	20 ÷ 25
- thatched building roofs	2.0 ÷ 4.0
- bedding in livestock buildings	1.5 ÷ 4.0
- steppe fires with high and dense grassy
cover, as well as crops in dry weather
and strong wind	400 ÷ 600
- steppe fires with low sparse vegetation
and calm weather	15 ÷ 18
Theaters and palaces of culture (stage)	1.0 ÷ 3.0
Trade enterprises, warehouses and bases
goods material assets	0.5 ÷ 1.2
Printing houses	0.5 ÷ 0.8
Milled peat (on production fields) at wind speed, m/s:
10 ÷ 14	8.0 ÷ 10
18 ÷ 20	18 ÷ 20
Refrigerators	0.5 ÷ 0.7
Schools, medical institutions:
- buildings of I and II degree of fire resistance	0.6 ÷ 1.0
- buildings III and IV degree of fire resistance	2.0 ÷ 3.0

Application No. 6

Intensity of water supply when extinguishing fires

Administrative buildings:

IV degree of fire resistance 0.1

V degree of fire resistance 0.15

basements 0.1

attic space 0.1

Hangars, garages, workshops, tram

and trolleybus depots 0.2

Hospitals; 0.1

Residential buildings and outbuildings:

I - III degree of fire resistance 0.06

IV degree of fire resistance 0.1

V degree of fire resistance 0.15

basements 0.15

attic rooms; 0.15

Animal buildings:

I - III degree of fire resistance 0.1

IV degree of fire resistance 0.15

V degree of fire resistance 0.2

Cultural and entertainment institutions (theaters, cinemas, clubs, palaces of culture):

Scene 0.2

Auditorium 0.15

Utility rooms 0.15

Mills and elevators 0.14

Industrial buildings:

I - II degree of fire resistance 0.15

III degree of fire resistance 0.2

IV - V degree of fire resistance 0.25

Painting shops 0.2

Basements 0.3

Attic space 0.15

Combustible coverings of large areas:

When extinguishing from below inside the building 0.15

When extinguishing outside from the side of the coating 0.08

When extinguishing outside with a developed fire 0.15

Buildings under construction 0.1

Trade enterprises and warehouses

inventory items 0.2

Refrigerators 0.1

Power plants and substations:

Cable tunnels and mezzanines

(innings mist water) 0,2

Machine rooms and boiler rooms 0.2

Fuel galleries 0.1

Transformers, reactors, oil

switches (water mist supply) 0.1

2. VEHICLES

Cars, trams, trolleybuses

in open parking areas 0.1

Planes and helicopters:

Interior decoration(when supplying mist water) 0.08

Designs with the presence of magnesium alloys 0.25

Housing 0.15

Vessels (dry cargo and passenger):

Superstructures (internal and external fires)

when supplying solid and finely sprayed jets 0.2

Holds 0.2

Loose paper 0.3

3. SOLID MATERIALS.

Wood:

Balance, at humidity%:

Less than 40 0.5

Lumber in stacks within the same group,

at humidity %:

Over 30 0.2

roundwood in stacks, within the same group 0.35

Chips in piles with moisture content 30-50% 0.1

Rubber (natural or artificial),

rubber and rubber-technical products ............... 0.3

Flax camp in dumps (supply of mist water) 0.2

Flax straw (stacks, bales) 0.25

Plastics:

Thermoplastics 0.14

Thermoplastics 0.1

Polymer materials and products from them 0.2

Textolite, carbolite, plastic waste,

triacetate film 0.3

Peat on milling fields with a moisture content of 15-30%

(at specific consumption water 110-140 l/m2

and extinguishing time 20 min) 0.1

Milling peat in stacks (with specific water consumption

235 d / m.kv, and extinguishing time 20 min.)......... 0.2

Cotton and other fibrous materials:

Open warehouses 0.2

Closed warehouses 0.3

Celluloid and products from it 0.4

Pesticides and fertilizers 0.2

5. FLAMMABLE

AND FLAMMABLE LIQUIDS

(when extinguishing thinly sprayed with other water)

Acetone 0.4

Oil products in containers:

With a flash point below 28 ° C ....... 0.4

With flash point from 28 to 60 gr.С 0.3

With a flash point of more than 60 ° C ...... 0.2

Flammable liquid spilled on the surface

platforms, in trenches and technological trays 0.2

Thermal insulation impregnated with oil products 0.2

Alcohols (ethyl, methyl, propid, butyl

and others) in warehouses and distilleries 0.2

Oil and condensate around the fountain well 0.4

Notes:

1. When water is supplied with a wetting agent, the intensity of supply according to the table is reduced by 2 times.

2. Extinguishing of cotton, other fibrous materials and peat must be carried out only with the addition of a wetting agent.

Application No. 7

Organization of extinguishing a possible fire by the first RTP.

Application No. 8

Estimated supply of fire extinguishing agents, taken into account when calculating the forces and means for extinguishing a fire.

Most fires:

water for extinguishing period 5

water for the period of extinguishing (dismantling,

pouring fire places, etc.), hour 3

Fires for volume extinguishing of which

non-flammable gases and vapors are used 2

Fires on ships:

fire extinguishing foam

MKO, holds and superstructures 3

Fires of oil and oil products in tanks:

Frother 3

fire extinguishing water with foam 5

water for cooling ground tanks:

mobile vehicles, hour 6

by stationary and means, hour 3

water for cooling underground tanks, hour 3

Note: The supply of water in reservoirs (reservoirs) when extinguishing fires of gas and oil fountains should ensure the uninterrupted work of fire departments during the daytime. This takes into account the replenishment of water during the day pumping units. As the practice of extinguishing fires shows, the total volume of water bodies is usually 2.5-5.0 thousand m 3.

Application No. 9

Resistance values ​​of one pressure hose 20 m long.

Sleeve type	Sleeve diameter, mm
Rubberized	0,15	0,035	0,015	0,004	0,002	0,00046
Non-rubberized	0,3	0,077	0,03	-	_	-

Application No. 10

Water return of water supply networks (approximately).

Head in the network, m	Type of water supply network	Pipe diameter, mm
Water pressure, l/s
	dead end
Ring
	dead end
Ring
	dead end
Ring
	dead end
Ring
	dead end
Ring

Appendix No. 11

Fire work in progress	Required number of people
Working with the RS-50 barrel on a flat plane (from the ground, floor, etc.)
Work with the barrel "RS-50" on the roof of the building
Working with the barrel "RS -70"	2-3
Working with the RS-50 or RS-70 barrel in an atmosphere unsuitable for breathing	3-4 (link GDZS)
Working with a portable fire monitor	3-4
Working with an air-foam barrel and a GPS-600 generator
Work with the GNS-2000 generator	3-4
Working with foam	2-3
Installing the foam maker	5-6 (separation)
Installation of a retractable portable fire escape
Retractable portable fire escape insurance after installation
Exploration in a smoky room	3 (link GDZS)
Exploration in large basements, tunnels, subways, lanternless buildings, etc.	6 (two links GDZS)
Rescue of victims from a smoky room and seriously ill patients (one victim)
Rescue of people on fire escapes and with the help of a rope (to the rescue site)	4-5
Branch work and control of the hose system: when laying hose lines in one direction (per machine) when laying two hose lines in opposite directions (per machine)
Opening and dismantling of structures: performing actions at the position of the shaft working on fire extinguishing (except for the barrel operator) performing actions at the position of the shaft working for protection (except for the barrel operator) by opening 1 m: plank sheet pile or parquet shield field plank nail or parquet piece floor plastered wooden partition or ceiling filing metal roofing rolled roofing on wooden formwork insulated combustible coating	at least 2 1-2 3-4
Water pumping: control over the flow of water into the tanker (for each machine) control over the operation of the hose system (per 100 m of the pumping line)
Water supply: accompanying person on the car work at the refueling point

Appendix No. 12

CARD

Combat operations ___________ guard HPV (PPV) No. _____________

on a fire that happened

__________________________________________________________

(day month Year)

(compiled for all fires)

1. Object __________________________________________________

(name of the object, departmental affiliation - ministry, department, address)

2. Type of building and its dimensions _________________________________

(number of floors, fire resistance and dimensions of the building in plan)

3. What and where burned __________________________________________

(floor, room, type, quantity of substances, materials, equipment)

4. Time: fire start _________, detection __________

fire announcement _____, departure of the duty guard _____, arrival

to a fire _____, supplying the first barrels _____, calling an additional

assistance ______, containment _______, liquidation _____, return

in part __________.

5. Composition of departing units ___________________________

(type of vehicles and number of combat crews)

6. Features and circumstances of the development of a fire _________________

7. Result of the fire __________________________________________

(burnt materials, substances, equipment and loss from fire)

8. Characteristics tactical actions on fire _______

___________________________________________________________

___________________________________________________________

9. Evaluation of the work of the guard _____________________________________

(positive aspects, shortcomings in the work of personnel, departments and RTP)

___________________________________________________________

10. Additional remarks (but the work of equipment, rear) ____________

11. Suggestions and measures taken _______________________________

12. A note on the analysis of the fire and on additional data obtained during the analysis of the fire ________________________________________

Appendix No. 13

Conditional graphic symbols

Tracked vehicle Vehicle communication and lighting fireman Gas and smoke protection service car Fire pumping station Fire truck with a fixed fire monitor Headquarters fire truck Fire extinguishing vehicle

FIRE SPECIAL VEHICLES		FIRE FIGHTING EQUIPMENT, SPECIAL TOOLS
seaplane firefighter			Branching sleeve three-way
Helicopter firefighter			Branching sleeve four-way
Motor pump fire portable trailed			Portable hose reel Mobile hose reel
Powder fire trailer			Sleeve bridge
Adapted vehicle for firefighting purposes			Hydraulic elevator fireman
Other adapted fire-fighting equipment			Foam mixer fireman
FIRE FIGHTING EQUIPMENT SPECIAL TOOLS		Fire column
Pressure fire hose			Hand fire barrel (general designation)
Suction fire hose	-		Barrel A with nozzle diameter (19.25 mm)
Sleeve water collector			Barrel for forming a finely atomized water (water-aerosol) jet
Branching sleeve two-way			Barrel for forming a water jet with additives
Barrel for forming low expansion foam (SVP-2, SVP-4, SVPE-4, SVPE-8)			Smoke exhauster fireman: portable trailed
Barrel for forming foam medium multiplicity(GPS-200, GPS-600, GPS-2000)
Barrel for extinguishing electrical installations under voltage			Ladder - stick
Trunk "B" On the third floor K - on the roof P - basement H - attic	GZDS		Retractable fire ladder
	FIRE EXTINGUISHING INSTALLATION
Fire monitor fire monitor portable stationary with water nozzles and powder stationary with foam nozzles transportable			Fixed fire extinguishing installation (general and local protection of the premises with automatic start)
Elevator foam drain			Stationary fire extinguishing installation with manual start
Foam lifter with generator comb GPS-600			Foam fire extinguishing installation
Installation of water-aerosol fire extinguishing			Water fire extinguishing installation
FIRE EXTINGUISHING INSTALLATIONS		CONTROL POINTS AND COMMUNICATIONS
fire extinguishing station			Traffic control post (traffic controller). With the letters checkpoint - checkpoint, P - traffic controller, PB - security post GZDS	PB R checkpoint
Carbon dioxide fire extinguishing station
Fire extinguishing station with other gas			Radio stations: mobile portable stationary
Installation of gas-aerosol fire extinguishing
Powder extinguishing installation			Speaker
Steam fire extinguishing installation			Telephone
FIRE EXTINGUISHERS		spotlight
Fire extinguisher portable (manual, knapsack) mobile			Headquarters location
SMOKE EXHAUST DEVICES		radio direction
Smoke exhaust device (smoke hatch)			Radio network
Smoke and heat exhaust devices			MOVEMENT OF UNITS, INTELLIGENCE
Manual control natural ventilation			Reconnaissance watch. With the letters HRD - chemical reconnaissance patrol			Internal fire with heat affected zone
Exit of forces from the occupied line			Outdoor fire with smoke zone
Locations of the victims			Location of the fire (center)
First Aid Squad			Separate fire from the area and the direction of its spread
Temporary casualty collection point			firestorm
SITUATION IN THE COMBAT ZONE		Fire zone and direction of its spread
Fire internal			Direction of fire development
Fire outdoor			The decisive direction of action of fire extinguishing forces and means
building on fire			The boundaries of the fire extinguishing area			Oil depot, fuel storage
Radiation measurement point indicating the radiation level, time and date of measurement			Complete destruction of a building (object, structure, road, gas pipeline, etc.)
Staircase connected to the attic	H		single track Railway
Furnaces			double track railway
Ventilation shaft			Crossing under the railroad
Elevator
		BUILDINGS, COMMUNICATIONS, WATER SOURCES
Crossing over the railroad			metal fence
Moving on the same level with the barrier			reinforced concrete fence
tram line			stone fence
Underground water supply			Earth embankment (bundling)
Pipeline			Ring water main			dead end water main			Well

fire chemical combat control

The growth rate of the fire area is the increase in the area of ​​fire over a period of time and depends on the rate of spread of combustion, the shape of the fire area and the effectiveness of combat operations. It is determined by the formula:

where: V sn- growth rate of the fire area, m 2 /min; ДS n - the difference between the subsequent and previous values ​​of the fire area, m 2 ; Df - time interval, min.

333 m2/min

2000 m2/min

2222 m2/min

Fig 2.

Conclusion from the graph: It can be seen from the graph that a very high rate of fire development occurred in the initial period of time, this is due to the properties of the burning material (flammable liquid-acetone). The spilled acetone quickly reached the limits of the room and the fire development of the fire was limited to fire walls. The rapid introduction of powerful water trunks and right action site personnel (an emergency drain was activated and a fire extinguishing system was launched that did not work in automatic mode, the supply ventilation was turned off).

Determination of the linear speed of propagation of combustion

In the study of fires, the linear speed of propagation of the flame front is determined in all cases, since it is used to obtain data on the average speed of propagation of combustion on typical objects. The spread of combustion from the original place of origin in different directions can occur at different speeds. The maximum rate of combustion propagation is usually observed: when the flame front moves towards the openings through which gas exchange is carried out; by fire load

This speed depends on the situation on the fire, the intensity of the supply of fire extinguishing agents (OTV), etc.

The linear rate of propagation of combustion, both with the free development of a fire and with its localization, is determined from the ratio:

where: L is the distance traveled by the combustion front in the studied time interval, m;

f 2 - f 1 - the time interval in which the distance traveled by the combustion front was measured, min.

MINISTRY OF THE RUSSIAN FEDERATION

FOR CIVIL DEFENSE, EMERGENCIES AND DISASTER RELIEF

Federal State Budgetary Institution All-Russian Order of the Badge of Honor Research Institute of Fire Defense EMERCOM of Russia

(FGBU VNIIPO EMERCOM of Russia)

APPROVE

Boss

FGBU VNIIPO EMERCOM of Russia

PhD

IN AND. Klimkin

Methodology

Tests to determine the linear speed of flame propagation

solids and materials

Professor N.V. Smirnov

Moscow 2013

This methodology is intended for use by specialists of the SEU FPS IPL EMERCOM of Russia, supervisory authorities of the EMERCOM of Russia, testing laboratories, research organizations, enterprises - manufacturers of substances and materials, as well as organizations working in the field of ensuring fire safety of objects.

The methodology was developed by the Federal State Budgetary Institution VNIIPO EMERCOM of Russia (Deputy Head of the Research Center for Fire Prevention and Emergency Prevention with Fires, Doctor of Technical Sciences, Professor N.V. Smirnov; Chief Researcher, Doctor of Technical Sciences, Professor N.I. Konstantinova; Head of the Sector , candidate of technical sciences O. I. Molchadsky, head of the sector A. A. Merkulov).

The methodology presents the fundamental provisions for determining the linear velocity of flame propagation over the surface of solids and materials, as well as a description of the installation, the principle of operation and other necessary information.

In this method, an installation is used, the basic design of which corresponds to GOST 12.1.044-89 (clause 4.19) "Method for experimental determination of the flame propagation index."

L. - 12, app. - 3

VNIIPO - 2013

Scope 4 Normative references 4 Terms and definitions 4 Test equipment 4 Test samples 5 Calibration of the installation 6 Conducting tests 6 Evaluation of test results 7 Drawing up a test report 7 Safety requirements 7 Appendix A (Mandatory) General view of the installation 9

Annex B (Mandatory) Relative position of the radiation panel

And a holder with a sample10

List of performers of the work12Scope

This procedure establishes requirements for the method for determining the linear velocity of flame propagation (LFPR) over the surface of horizontally located samples of solids and materials.

This practice applies to combustible solids and materials, incl. construction, as well as paint coatings.

The technique does not apply to substances in gaseous and liquid form, as well as bulk materials and dust.

The test results are only applicable to assess the properties of materials under controlled laboratory conditions and do not always reflect the behavior of materials in real fire conditions.

This methodology uses normative references to the following standards:

GOST 12.1.005-88 System of labor safety standards. General sanitary and hygienic requirements for the air of the working area.

GOST 12.1.019-79 (2001) Occupational safety standards system.

Electrical safety. General requirements and nomenclature of types of protection.

GOST 12.1.044-89 Fire and explosion hazard of substances and materials.

Nomenclature of indicators and methods for their determination.

GOST 12766.1-90 Wire made of precision alloys with high electrical resistance.

GOST 18124-95 Flat asbestos-cement sheets. Specifications.

GOST 20448-90 (as amended 1, 2) Liquefied hydrocarbon fuel gases for domestic consumption. Specifications.

Terms and Definitions

In this methodology, the following terms are used with the corresponding definitions:

Flame Linear Velocity: The distance traveled by the flame front per unit time. This is a physical quantity characterized by the translational linear motion of the flame front in a given direction per unit time.

Flame Front: The area of ​​spreading open flame in which combustion occurs.

Test Equipment

The installation for determining the linear velocity of flame propagation (Figure A.1) includes the following elements: a vertical stand on a support, an electric radiation panel, a sample holder, exhaust hood, gas burner and thermoelectric converter.

The electric radiation panel consists of a ceramic plate, in the grooves of which a heating element (spiral) made of wire grade Х20Н80-Н (GOST 12766.1) is evenly fixed. The parameters of the spiral (diameter, winding pitch, electrical resistance) must be such that the total power consumption does not exceed 8 kW. The ceramic plate is placed in a thermally electrically insulated case, fixed on a vertical stand and

Connected to electrical network using the power supply. To increase the power of infrared radiation and reduce the influence of air flows, a grid of heat-resistant steel is installed in front of the ceramic plate. The radiation panel is installed at an angle of 600 to the surface of a horizontal sample.

The sample holder consists of a stand and a frame. The frame is fixed on the stand horizontally so that the lower edge of the electric radiation panel is from the upper plane of the frame with the sample at a distance of 30 mm vertically and 60 mm horizontally (Figure B.1).

On the side surface of the frame, control divisions are applied every (30 ± 1) mm.

An exhaust hood with dimensions (360×360×700) mm, installed above the sample holder, serves to collect and remove combustion products.

4.5. The gas burner is a tube with a diameter of 3.5 mm made of heat-resistant steel with a soldered end and five holes located at a distance of 20 mm from each other. The burner in the working position is installed in front of the radiation panel parallel to the sample surface along the length of the middle of the zero section. The distance from the burner to the surface of the test sample is (8 ± 1) mm, and the axes of the five holes are oriented at an angle of 450 to the surface of the sample. To stabilize the pilot flame, the burner is placed in a single-layer cover made of metal mesh. The gas burner is connected by a flexible hose through a valve that regulates the gas flow to a cylinder with propane - butane fraction. The gas pressure must be in the range (10÷50) kPa. In the “control” position, the burner is taken out of the frame edge.

The power supply unit consists of a voltage regulator with a maximum load current of at least 20 A and an adjustable output voltage from 0 to 240 V.

A device for measuring time (stopwatch) with a measurement range of (0-60) min and an error of no more than 1 s.

Hot-wire anemometer - designed to measure the speed of the air flow with a measurement range of (0.2-5.0) m/s and an accuracy of ±0.1 m/s.

To measure temperature (reference indicator) when testing materials, a thermoelectric transducer of the TXA type with a thermoelectrode diameter of not more than 0.5 mm, an insulated junction, with a measurement range of (0-500) ° C, not more than 2 accuracy classes, is used. The thermoelectric converter must have a stainless steel protective casing with a diameter of (1.6 ± 0.1) mm, and be fixed in such a way that the insulated junction is in the center of the section of the constricted part of the exhaust hood.

A device for recording temperature with a measurement range (0-500) ° C, not more than 0.5 accuracy class.

To measure linear dimensions, use a metal ruler or tape measure with a measurement range of (0-1000) mm, etc. 1 mm.

To measure atmospheric pressure, a barometer with a measurement range of (600-800) mm Hg is used. and c.d. 1 mmHg

To measure air humidity, use a hygrometer with a measurement range of (20-93)%, (15-40) ° C, and c.d. 0.2.

Samples for testing

5.1. To test one type of material, five samples are made with a length of (320 ± 2) mm, a width of (140 ± 2) mm, and an actual thickness, but not more than 20 mm. If the thickness of the material is more than 20 mm, it is necessary to cut off a part

material with no front side so that the thickness is 20 mm. During the preparation of samples, the exposed surface should not be processed.

For anisotropic materials, two sets of samples are made (for example, weft and warp). When classifying the material, the worst test result is accepted.

For laminates with different surface layers, two sets of samples are made to expose both surfaces. When classifying the material, the worst test result is accepted.

Roofing mastics, mastic coatings and paint coatings are tested on the same substrate as used in the actual construction. In this case, paint coatings should be applied at least four layers, with the consumption of each layer, in accordance with the technical documentation for the material.

Materials less than 10 mm thick are tested in combination with a non-combustible substrate. The fastening method must ensure close contact between the surfaces of the material and the base.

As a non-flammable base, use asbestos cement sheets dimensions (320×140) mm, thickness 10 or 12 mm, manufactured in accordance with GOST 18124.

Samples are conditioned under laboratory conditions for at least 48 hours.

Installation calibration

Calibration of the unit must be carried out indoors at a temperature of (23±5)C and a relative humidity of (50±20)%.

Measure the air flow velocity in the center of the section of the constricted part of the exhaust hood. It should be in the range (0.25÷0.35) m/s.

Adjust the gas flow through the pilot gas burner so that the height of the flames is (11 ± 2) mm. After that, the pilot burner is turned off and transferred to the “control” position.

Turn on the electric radiation panel and install the sample holder with a calibration asbestos-cement plate, in which holes with sensors are located heat flow at three control points. Hole centers (control points) are located along the central longitudinal axis from the edge of the frame of the sample holder at a distance of 15, 150 and 280 mm, respectively.

Heat the radiation panel, providing the heat flux density in stationary mode for the first control point (13.5±1.5) kWm2, for the second and third points, respectively, (9±1) kWm2 and (4.6± 1) kWm2. The heat flux density is controlled by a Gordon-type sensor with an error of not more than

The radiation panel entered the stationary mode if the readings of the heat flux sensors reach the values ​​of the specified ranges and remain unchanged for 15 minutes.

Testing

Tests should be carried out indoors at a temperature of (23±5)C and a relative humidity of (50±20)%.

Set the air flow rate in the hood according to 6.2.

Heat up the radiant panel and check the heat flux density at three control points according to 6.5.

Fix the test sample in the holder, apply marks on the front surface with a step of (30 ± 1) mm, light the pilot burner, transfer it to the working position and adjust the gas flow according to 6.3.

Place the holder with the test sample in the installation (according to Figure B.1) and turn on the stopwatch at the moment the ignition burner flame contacts the sample surface. The ignition time of the sample is considered to be the moment when the flame front passes through the zero area.

The test lasts until the propagation of the flame front over the surface of the sample stops.

During the test, fix:

Sample ignition time, s;

Time i for the flame front to pass each i-th section of the sample surface (i = 1.2, ... 9), s;

Total time  for the flame front to pass through all sections, s;

Distance L, to which the flame front has spread, mm;

Maximum flue gas temperature Тmax, C;

Time to reach maximum temperature flue gases, s.

Evaluation of test results

For each sample, calculate the linear velocity of flame propagation over the surface (V, m/s) using the formula

V= L /  ×10-3

The arithmetic mean of the linear velocity of flame propagation over the surface of the five tested specimens is taken as the linear velocity of flame propagation over the surface of the test material.

8.2. The convergence and reproducibility of the method with a confidence level of 95% should not exceed 25%.

Registration of the test report

The test report (Appendix B) provides the following information:

Name of the testing laboratory;

Name and address of the customer, manufacturer (supplier) of the material;

Indoor conditions (temperature, °C; relative humidity, %, Atmosphere pressure, mmHg);

Description of the material or product, technical documentation, trademark;

Composition, thickness, density, mass and method of manufacturing samples;

For multilayer materials - the thickness and characteristics of the material of each layer;

Parameters recorded during tests;

Arithmetic mean value of the linear speed of flame propagation;

Additional observations (behavior of the material during testing);

Performers.

Safety requirements

The room in which the tests are carried out must be equipped with supply and exhaust ventilation. The operator's workplace must

Satisfy the requirements of electrical safety in accordance with GOST 12.1.019 and sanitary hygiene requirements according to GOST 12.1.005. Persons admitted to testing in accordance with the established procedure must be familiar with the technical description and operating instructions for testing and measuring equipment.

Annex A (mandatory)

General view of the installation

1 - vertical stand on a support; 2 - electric radiation panel; 3 - sample holder; 4 - exhaust hood; 5 - gas burner;

6 – thermoelectric converter.

Figure A.1 - General view of the installation

Annex B (mandatory)

Mutual arrangement of the radiation panel and the holder with the sample

1 - electric radiation panel; 2 – sample holder; 3 - sample.

Figure B.1 - Mutual arrangement of the radiation panel and the holder with the sample

Test report form

Name of the organization performing the tests PROTOCOL No.

Determination of the linear speed of flame propagation over the surface

From "" Mr.

Customer (Manufacturer):

Name of material (brand, GOST, TU, etc.):

Material characteristics (density, thickness, composition, number of layers, color):

Conditions in the room (temperature, OS; relative humidity,%; atmospheric pressure, mm Hg):

Name of the test procedure:

Testing and measuring equipment (serial number, brand, verification certificate, measurement range, validity period):

Experimental data:

No. Time, s. Maxim. flue gas temperature Time of passage of the flame front through surface areas No. 19 Flame spread indicators

Ignition Achievements Tmax1 2 3 4 5 6 7 8 9 Length L, mm Linear velocity V, m/s1 2 3 4 5 Note: Conclusion: Performers:

List of performers of the work:

Chief Researcher, Doctor of Technical Sciences, Prof. N.I. Konstantinova Head of Sector, Candidate of Technical Sciences O.I. Molchadsky Head of Sector A.A. Merkulov

Above the surface of a liquid or solid at any temperature there is a vapor-air mixture, the pressure of which in the state of equilibrium is determined by the pressure of saturated vapors or their concentration. With an increase in temperature, the saturated vapor pressure will increase but exponentially (Clapeyron - Clausis equation):

where P n „ - pressure of saturated steam, Pa; Q„ C11 - heat of vaporization, kJ/mol; T - liquid temperature, K.

For any liquid, there is a temperature range in which the concentration of saturated vapors above the mirror (liquid surface) will be in the ignition region, i.e. NKPV

In order to create LCVV of vapors, it is sufficient to heat not the entire liquid, but only its surface layer, to a temperature equal to the LTPV.

In the presence of an ignition source, such a mixture will be capable of ignition. In practice, the concepts of "flash point" and "ignition temperature" are more often used.

Flash point - the minimum temperature of a liquid at which a concentration of vapor forms above its surface, capable of being ignited by an ignition source, but the rate of vapor formation is insufficient to sustain combustion.

Thus, both at the flash point and at the lower temperature limit of ignition above the surface of the liquid, a lower concentration limit of ignition is formed, however, in the latter case, LEL is created by saturated vapors. Therefore, the flash point is always somewhat higher than the LTLW. Although at the flash point there is a short-term ignition of the vapor, which is not capable of turning into a stable combustion of the liquid, nevertheless, under certain conditions, the flash can cause a fire.

The flash point is taken as the basis for the classification of liquids into flammable (flammable liquids) and combustible liquids (FL). Flammable liquids include liquids with a flash point in a closed vessel of 61 ° C and below, combustible liquids with a flash point of more than 61 ° C.

Experimentally, the flash point is determined in open and closed devices. In closed vessels, flash points are always lower than in open vessels, because in this case liquid vapors have the opportunity to diffuse into the atmosphere and a higher temperature is required to create a combustible concentration above the surface.

In table. 2.4 shows the flash point of some liquids, determined by devices of open and closed type.

Table 2.4

The flash point of different types of liquid at different methods definitions

Ignition temperature - the minimum temperature of a liquid at which, after ignition of vapors from an ignition source, stationary combustion is established.

In flammable liquids, the ignition temperature is higher than the flash point by 1-5 °, while the lower the flash point, the smaller the difference between the ignition and flash points.

For combustible liquids with a high flash point, the difference between these temperatures reaches 25-35 °. There is a correlation between the flash point in a closed crucible and the lower ignition temperature limit, described by the formula

This relation is valid for Г В(.

The significant dependence of the flash and ignition temperatures on the experimental conditions causes certain difficulties in creating a calculation method for estimating their values. One of the most common of them is the semi-empirical method proposed by V. I. Blinov:

where G sun - flash point (ignition), K; R np - partial pressure of saturated vapor of liquid at flash point (ignition), Pa; D()- diffusion coefficient of liquid vapors, s/m 2 ; b- the number of oxygen molecules required for the complete oxidation of one fuel molecule; AT - definition method constant.

When calculating the flash point in a closed vessel, it is recommended to take AT= 28, in an open vessel AT= 45; to calculate the ignition temperature, take AT = 53.

The flammable temperature limits can be calculated:

According to the known values ​​of the boiling point

where ^n(v)' 7/ip - lower (upper) temperature limit of ignition and boiling point, respectively, °C; k, I- parameters, the values ​​of which depend on the type of combustible liquid;

According to known values ​​of concentration limits. To do this, first determine the concentration of saturated vapors above the surface of the liquid

where (р„ n is the concentration of saturated vapors, %; R n p - saturated vapor pressure, Pa; P 0 - external (atmospheric) pressure, Pa.

From formula (2.41) it follows

Having determined the pressure of saturated vapor by the value of the lower (upper) ignition limit, we find the temperature at which this pressure is reached. It is the lower (upper) temperature limit of ignition.

Using formula (2.41), one can also solve the inverse problem: calculate concentration limits ignition according to known values ​​​​of temperature limits.

The property of a flame to spontaneous propagation is observed not only during the combustion of mixtures of combustible gases with an oxidizing agent, but also when burning liquids and solids. Under local exposure to a heat source, such as an open flame, the liquid will warm up, the evaporation rate will increase, and when the surface of the liquid reaches the ignition temperature at the point of impact heat source the vapor-air mixture will be ignited, a stable flame will be established, which will then spread at a certain speed over the surface and the cold part of the liquid.

What is the driving force behind the propagation of the combustion process, what is its mechanism?

Flame propagation over the liquid surface proceeds as a result of heat transfer due to radiation, convection and molecular heat conduction from the flame zone to the surface of the liquid mirror.

According to modern concepts, the main driving force for the spread of the combustion process is heat radiation from the flame. The flame, having a high temperature (more than 1000 ° C), is capable, as you know, of emitting thermal energy. According to the Stefan-Boltzmann law, the intensity of the radiant heat flux given off by a heated body is determined by the relation

where c i- intensity of radiant heat flow, kW/m 2 ; 8 0 - degree of blackness of the body (flame) (e 0 \u003d 0.75-H.0); a = = 5.7 10 11 kJ / (m 2 s K 4) - Stefan-Boltzmann constant; Г g - temperature of the body (flame), K; Г 0 - medium temperature, K.

Heat, radiating in all directions, partially enters the areas of the surface of the liquid that have not yet caught fire, warming them up. With an increase in the temperature of the surface layer above the heated area, the process of liquid evaporation is intensified and a vapor-air mixture is formed. As soon as the liquid vapor concentration exceeds the NKVP, it will be ignited from the flame. Then, this section of the liquid surface begins to intensively heat up the adjacent section of the liquid surface, and so on. The rate of flame propagation through the liquid depends on the rate of heating of the liquid surface by the radiant heat flux from the flame, i.e. on the rate of formation of a combustible vapor-air mixture above the liquid surface, which, in turn, depends on the nature of the liquid and the initial temperature.

Each type of liquid has its own heat of vaporization and flash point. The higher their values, the longer the time required for its heating to form a combustible vapor-air mixture, the lower the flame propagation speed. With an increase in the molecular weight of a substance within one homologous series the elasticity vapor pressure decreases, the heat of vaporization and the flash point increase, respectively, the flame propagation speed decreases.

Increasing the temperature of the liquid increases the speed of flame propagation, since the time required for the liquid to warm up to the flash point in front of the combustion zone is reduced.

During a flash, the speed of flame propagation along the liquid mirror will be (in physical terms) equal to the speed of flame propagation through the vapor-air mixture of a composition close to the LCV, i.e. 4-5 cm/s. With an increase in the initial temperature of the liquid above the flash point, the flame propagation rate will depend (similarly to the flame propagation rate) on the composition of the combustible mixture. Indeed, as the temperature of the liquid rises above its flash point, the concentration of the vapor-air mixture above the surface of the mirror will increase from NKVP to 100% (boiling point).

Therefore, initially, as the temperature of the liquid rises from the flash point to the temperature at which saturated vapors are formed above the surface, with a concentration equal to the stoichiometric (more precisely, somewhat higher than the stoichiometric), the flame propagation rate will increase. In closed vessels, as the temperature of the liquid rises further, the flame propagation rate begins to decrease, down to the speed corresponding to the upper temperature limit of ignition, at which the propagation of the flame and the vapor-air mixture will no longer be possible due to the lack of oxygen in the vapor-air mixture above the surface of the liquid. Above the surface of an open reservoir, the concentration of vapors at different levels will be different: at the surface it will be maximum and correspond to the concentration of saturated vapor at a given temperature, as the distance from the surface increases, the concentration will gradually decrease due to convective and molecular diffusion.

At a liquid temperature close to the flash point, the speed of flame propagation over the surface of the liquid will be equal to the speed of its propagation through the mixture of vapors in air at the LIP, i.e. 3-4 cm/s. In this case, the flame front will be located near the surface of the liquid. With a further increase in the initial temperature of the liquid, the flame propagation velocity will increase similarly to the growth of the normal flame propagation velocity in the vapor-air mixture with an increase in its concentration. At maximum speed, the flame will propagate through the mixture with a concentration close to stoichiometric. Consequently, with an increase in the initial temperature of the liquid above G stx, the flame propagation rate will remain constant, equal to the maximum value of the combustion propagation rate in the stoichiometric mixture or somewhat greater than it (Fig. 2.5). Thus,

Rice. 25.

1 - burning liquid in a closed container; 2 - combustion of a liquid in an open container with a change in the initial temperature of the liquid in an open container in a wide temperature range (up to the boiling point), the flame propagation velocity will vary from a few millimeters to 3-4 m / s.

At maximum speed, the flame will propagate through the mixture with a concentration close to stoichiometric. With an increase in the temperature of the liquid above Гstx, the distance above the liquid will increase, at which the stoichiometric concentration will form, and the flame propagation speed will remain the same (see Fig. 2.5). This circumstance must always be remembered, both when organizing preventive work and when extinguishing fires, when, for example, there may be a danger of air being sucked into a closed container - its depressurization.

After the ignition of the liquid and the spread of the flame, but its surface is established diffusion mode of its burnout, which is characterized by the specific mass WrM and linear W V Jl speeds.

Specific mass velocity - the mass of a substance that burns out from a unit area of ​​​​a liquid mirror per unit time (kg / (m 2 * s)).

Linear speed - the distance over which the level of the liquid mirror moves per unit time due to its burnout (m / s).

The mass and linear burnout rates are interconnected through the liquid density p:

After ignition of the liquid, its surface temperature rises from the ignition temperature to boiling, and a heated layer is formed. During this period, the rate of burning out of the liquid gradually increases, the height of the flame increases depending on the diameter of the tank and the type of combustible liquid. After 1–10 minutes of combustion, the process stabilizes: the burnout rate and flame dimensions remain unchanged in the future.

The height and shape of the flame during diffusion combustion of liquid and gas obey the same laws, since in both cases the combustion process is determined by the mutual diffusion of the fuel and oxidizer. However, if during diffusion combustion of gases, the speed of the gas jet does not depend on the processes occurring in the flame, then during the combustion of a liquid, a certain burnout rate is established, which depends both on the thermodynamic parameters of the liquid and on the conditions of diffusion of air oxygen and liquid vapor.

A certain heat and mass transfer is established between the combustion zone and the liquid surface (Fig. 2.6). Part of the heat flux arriving at the surface of the liquid q 0y is spent on heating it to the boiling point q ucn . In addition, warm q CT for heating the liquid comes from the torch of the flame through the walls of the tank due to heat conduction. With a sufficiently large diameter q CT can be neglected, then q() = K „ n +

It's obvious that

where c is the heat capacity of the liquid, kJDkg-K); p is the density of the liquid, kg / m 3; Wnc- growth rate of the heated layer, m/s; W Jl- linear burnout rate, m/s; 0i SP - heat of vaporization, kJ/kg; G kip - the boiling point of the liquid, K.

Rice. 2.6.

Г () - initial temperature; G kip - boiling point;

T g- combustion temperature; q KUW q Jl - convective and radiant heat fluxes, respectively; q 0 - heat flux entering the surface of the liquid

It follows from formula (2.45) that the intensity of the heat flow from the flame zone determines a certain rate of fuel supply to this zone, the chemical interaction of which with the oxidizer, in turn, affects the value # 0 . This is what it consists the relationship of mass and heat exchange between the flame zone and the condensed phase during the combustion of liquids and solids.

Estimation of the share of heat from the total heat release during the combustion of the liquid, which is spent on its preparation for combustion q 0 , can be carried out in the following sequence.

Taking for simplicity wrijl= W nx , we get

The rate of heat release per unit surface of the liquid mirror (specific heat of fire qll7K) can be determined by the formula

where Q H is the lowest calorific value of the substance, kJ/kg; P p - coefficient of completeness of combustion.

Then, taking into account state (2.44) and dividing expression (2.45) by formula (2.46), we obtain

Calculations show that about 2% of the total heat release during liquid combustion is spent on the formation and delivery of liquid vapor to the combustion zone. When the burnout process is established, the temperature of the liquid surface increases to the boiling point, which subsequently remains unchanged. This statement refers to an individual liquid. If we consider mixtures of liquids having different temperature boiling, then at first there is an exit of light-boiling fractions, then - more and more high-boiling fractions.

The burn-up rate is significantly affected by the heating of the liquid in depth as a result of heat transfer from the liquid heated by the radiant flow q0 the surface of the liquid to its depth. This heat transfer is carried out by thermal conductivity and conventions.

The heating of a liquid due to thermal conductivity can be represented by an exponential dependence of the form

where T x - temperature of the liquid layer at depth X, TO; G kip - surface temperature (boiling point), K; k- coefficient of proportionality, m -1 .

This type of temperature field is called temperature distribution of the first kind(Fig. 2.7).

The laminar convention arises as a result of different liquid temperatures at the walls of the tank and in its center, as well as due to fractional distillation in the upper layer during the combustion of the mixture.

Additional heat transfer from the heated walls of the reservoir to the liquid leads to heating of its layers near the walls to more high temperature than in the center. The liquid heated near the walls (or even steam bubbles if it is heated near the walls above the boiling point) rises, which contributes to intensive mixing and rapid heating of the liquid at a great depth. The so-called homothermal layer, those. a layer with a practically constant temperature, the thickness of which increases during combustion. Such a temperature field is called temperature distribution of the second kind.

Rice. 2.7.

1 - temperature distribution of the first kind; 2 - temperature distribution of the second kind

The formation of a homothermal layer is also possible as a result of fractional distillation of near-surface layers of a mixture of liquids having different temperature boiling. As such liquids burn out, the near-surface layer is enriched in denser, high-boiling fractions, which sink down, contributing to the most convective heating of the liquid.

It has been established that the lower the boiling point of a liquid (diesel fuel, transformer oil), the more difficult it is to form a homothermal layer. When they burn, the temperature of the tank walls rarely exceeds the boiling point. However, when burning wet high-boiling oil products, the probability of the formation of a homothermal layer is rather high. When the tank walls are heated to 100°C and higher, water vapor bubbles are formed, which, rushing upward, cause an intensive movement of the entire liquid and rapid heating in depth. The dependence of the thickness of the homothermal layer on the burning time is described by the relation

where X - thickness of the homothermal layer at a certain moment of combustion time, m; x pr - limiting thickness of the homothermal layer, m; t is the time counted from the beginning of the layer formation, s; p - coefficient, s -1.

The possibility of the formation of a sufficiently thick homothermal layer during the combustion of wet oil products is fraught with the occurrence of boiling and liquid ejection.

The burn-out rate significantly depends on the type of liquid, initial temperature, humidity and oxygen concentration in the atmosphere.

From equation (2.45), taking into account expression (2.44), it is possible to determine the mass burnout rate:

It is obvious from formula (2.50) that the rate of burnout is affected by the intensity of the heat flux coming from the flame to the liquid mirror and the thermophysical parameters of the fuel: boiling point, heat capacity and heat of evaporation.

From Table. 2.5 it is obvious that there is a certain correspondence between the burnout rate and the heat costs for heating and evaporating the liquid. Thus, in the series of benzenexyleneglycerols, with an increase in heat consumption for heating and evaporation, the burnout rate decreases. However, when passing from benzene to diethyl ether, the heat costs decrease. This apparent discrepancy is due to the difference in the intensity of heat fluxes coming from the flame to the liquid surface. The radiant flux is large enough for a smoky benzene flame and small for a relatively transparent diethyl ether flame. As a rule, the ratio of the burnout rates of the fastest burning liquids and the slowest burning liquids is quite small and amounts to 3.0-4.5.

Table 25

Dependence of the burn-out rate on heat consumption for heating and evaporation

It follows from expression (2.50) that with an increase in Г 0 the burnout rate increases, since the heat costs for heating the liquid to the boiling point decrease.

The moisture content in the mixture reduces the burnout rate of the liquid, firstly, due to additional heat consumption for its evaporation, and secondly, as a result of the phlegmatizing effect of water vapor in the gas zone. The latter leads to a decrease in the temperature of the flame, and therefore, according to formula (2.43), its radiant power also decreases. Strictly speaking, the rate of burning of a wet liquid (liquid containing water) is not constant, it increases or decreases during the combustion process depending on the boiling point of the liquid.

Wet fuel can be represented as a mixture of two liquids: fuel + water, during the combustion of which their fractional dispersal. If the boiling point of a combustible liquid is less than the boiling point of water (100°C), then the fuel burns out preferentially, the mixture is enriched with water, the burnout rate decreases, and, finally, combustion stops. If the boiling point of the liquid is more than 100 ° C, then, on the contrary, moisture primarily evaporates first and its concentration decreases. As a result, the burnout rate of the liquid increases, up to the burning rate of the pure product.

As a rule, with an increase in wind speed, the rate of burnout of the liquid increases. The wind intensifies the process of mixing the fuel with the oxidizer, thereby raising the temperature of the flame (Table 2.6) and bringing the flame closer to the combustion surface.

Table 2.6

Effect of wind speed on flame temperature

All this increases the intensity of the heat flow supplied to the heating and evaporation of the liquid, therefore, leads to an increase in the burnout rate. At higher wind speeds, the flame can break off, which will lead to the cessation of combustion. So, for example, when tractor kerosene burned in a tank with a diameter of 3 m, flameout occurred at a wind speed of 22 m/s.

Most liquids cannot burn in an atmosphere with less than 15% oxygen. With an increase in the oxygen concentration above this limit, the burn-up rate increases. In an atmosphere significantly enriched with oxygen, the combustion of a liquid proceeds with the release of a large number soot in the flame and intense boiling of the liquid phase is observed. For multicomponent liquids (gasoline, kerosene, etc.), the surface temperature increases with an increase in the oxygen content in the environment.

An increase in the burn-out rate and liquid surface temperature with an increase in the oxygen concentration in the atmosphere is due to an increase in the emissivity of the flame as a result of an increase in the combustion temperature and a high soot content in it.

The burnout rate also changes significantly with a decrease in the level of flammable liquid in the tank: the burnout rate decreases, up to the cessation of combustion. Since the supply of air oxygen from the environment inside the tank is difficult, when the liquid level decreases, the distance h np between the flame zone and the combustion surface (Fig. 2.8). The radiant flux to the liquid mirror decreases, and, consequently, the burnout rate also decreases, up to attenuation. When burning liquids in tanks of large diameter, the limiting depth /g pr at which combustion is attenuated is very large. So, for a tank with a diameter of 5 m, it is 11 m, and with a diameter of Im - about 35 m.

original document?

Fire parameters: duration, area, temperature, heat, linear speed of fire propagation, burnout rate of combustible substances, intensity of gas exchange, smoke density. Lecture 2

It is known that the main phenomenon in a fire- combustion, but the fires themselves are all individual. There are various types and modes of combustion: kinetic and diffusion, homogeneous and heterogeneous, laminar and turbulent, difflagration and detonation, complete and incomplete, etc.). The conditions under which combustion occurs are varied; the state and location of combustible substances, heat and mass transfer in the combustion zone, etc. Therefore, each fire must be registered, described, investigated, compared with others, i.e. study the parameters of the fire.

The duration of the fire τ P (min.). The duration of a fire is the time from the moment of its occurrence until the complete cessation of combustion.

fire area,F P (m 2). The fire area is the area of ​​the projection of the combustion zone on a horizontal or vertical plane.

On the rice. 1 typical cases of determining the area of ​​fire are shown. On internal fires in multi-storey buildings total area fire is found as the sum of the fire areas of all floors. In most cases, projection onto a horizontal plane is used, relatively rarely - to vertical (when burning a single structure of small thickness, located vertically, in case of a fire at a gas fountain).

The fire area is the main parameter of a fire when assessing its size, when choosing a method of extinguishing, when calculating the forces and means necessary for its localization and liquidation.

fire temperature, T P ( K). Under the temperature of an internal fire is understood the average volumetric temperature of the gaseous medium in the room, and under the temperature of an open fire- flame temperature. The temperature of internal fires is lower than open fires.

Linear speed of fire propagation, Vp (m/s). This parameter is understood as the rate of propagation of combustion over the surface of a combustible material per unit time. The linear rate of propagation of combustion determines the area of ​​the fire. It depends on the type and nature of combustible substances and materials, on the ability to ignite and the initial temperature, on the intensity of gas exchange in a fire and the direction of convective gas flows, on the degree of fineness of combustible materials, their spatial arrangement and other factors.

Linear flame propagation velocity- the value is not constant in time, therefore, average values ​​are used in the calculations, which are approximate values.

The highest linear speed of propagation of combustion have gases, since they are already prepared for combustion in a mixture with air, it is only necessary to heat this mixture to the ignition temperature.

Linear flame propagation velocity liquids depends on their initial temperature. The highest linear rate of propagation of combustion for combustible liquids is observed at the ignition temperature, and is equal to the rate of propagation of combustion in vapor-air mixtures.

Solid combustible materials have the lowest linear rate of propagation of combustion, for the preparation for combustion of which more heat is required than for liquids and gases. The linear rate of propagation of combustion of solid combustible materials largely depends on their spatial arrangement. Flame propagation on vertical and horizontal surfaces differs by 5- 6 times, and when the flame spreads along a vertical surface from bottom to top and from top to bottom- 10 times. The linear speed of propagation of combustion along a horizontal surface is more often used.

The rate of burning of combustible substances and materials. It is one of the most important combustion parameters in a fire. The burnout rate of combustible substances and materials determines the intensity of heat release in a fire, and, consequently, the temperature of the fire, the intensity of its development, and other parameters.

Bulk burnout rate is the mass of a substance or material burned out per unit of time V M (kg/s). The mass burnout rate, as well as the rate of combustion propagation, depends on the state of aggregation of the combustible substance or material.

combustible gases mix well with the surrounding air, so they burn completely in the flame. Bulk burnout rate liquids is determined by the rate of their evaporation, the entry of vapors into the combustion zone and the conditions for their mixing with atmospheric oxygen. The evaporation rate in the equilibrium state of the "liquid-vapor" system depends on the physicochemical properties of the liquid, its temperature, and vapor pressure. In a non-equilibrium state, the intensity of liquid evaporation is determined by the temperature of its surface layer, which in turn depends on the intensity of heat fluxes from the combustion zone, the heat of evaporation, and the conditions of heat exchange with the lower layers of the liquid.

For multicomponent combustible liquids, the composition of their vapor phase is determined by the concentration composition of the solution and depends on the intensity of evaporation and the degree of equilibrium. With intensive evaporation, the process of distillation occurs in the surface layers of the liquid, and the composition of the vapor phase differs from the equilibrium one, and the mass burnout rate changes as the burnout of more volatile fractions.

The process of burnout depends on the mixing of liquid vapor with atmospheric oxygen. Thisthe process depends on the size of the vessel, on the height of the side above the liquid level (the length of the mixing path to the combustion zone) and the intensity of external gas streams. The larger the diameter of the vessel (up to 2- 2.5 m, further increasediameter does not affect the parameter in question) and the height of the side above liquid level, the longer the path of the liquid to the combustion zone, respectively, the lower the burnout rate. The high wind speed and the temperature of the combustible liquid contribute to better mixing of liquid vapors with atmospheric oxygen and an increase in speed liquid burnout.

The mass of liquid burnt per unit time per unit surface area is called specific mass burnout rate V M , kg/(m 2 s).

Volumetric burnout rate is the volume of liquid burned per unit time per unit area of ​​the combustion surface,V O . For gases - is the volume of gas burned per unit time m / s, for liquids and solids and materials- is the specific volumetric burnup rate m /(m . s) or m/s, i.e. is the linear speed. The volumetric velocity expresses the rate of decrease in the level of the liquid as it burns out or the rate of burnout of the thickness of the layer of solid combustible material.

The actual volumetric burnout rate- it is the rate at which the level of a liquid decreases as it burns out, or the rate at which the thickness of a solid combustible material burns out. The conversion of volumetric (linear) velocity into mass velocity can be carried out according to the formula:V m = .

Burnout rate of thin (< 10 мм) слоев жидкости и пленок выше усредненной массовой или линейной скорости выгорания жидкости верхнего уровня резервуара при отсутствии ветра. Скорость выгорания твердых материалов зависит от вида горючего, его состояния (размеров, величины свободной поверхности, положения по отношению к зоне горения и т.д.), температуры пожара, интенсивности газообмена. Удельная массовая the burnout rate of solid combustible materials does not exceed 0.02 kg / (m 2 s) and is rarely below 0.005 kg/(m 2 s).

The mass burnout rate of solid combustible materials depends on the ratio of the opening area (F np), through which gas exchange is carried out, to the fire areaF np/Fn . For example, for wood, with a decrease in the area of ​​​​openings, the burnout rate decreases.

Reduced mass rate of wood burnout, kg/(m 2 s).	Relative area of ​​openings,F pr. / F p.
0.0134	0.25
0.0125	0.20
0.0108	0.16
0.009	0.10

The burnout rate of solid combustible materials is takenproportional to the area of ​​the openings, i.e.

V ppm = φ . V m.t. = . V m .t ,

where V ppm - actual reduced mass burnout rate; V m .t - tabular reduced mass burnout rate; φ- coefficient taking into account the conditions of gas exchange. This expression is valid for φ = 0.25- 0.085, and for open fires take φ = 1.

Intensity of gas exchange I t, kg/(m 2 ּ c) - This is the amount of air entering per unit time per unit area of ​​the fire. Distinguish the required intensity of gas exchange and actual. The required rate of gas exchange shows how much air is needed to enter per unit time per unit area to ensure complete combustion material. The actual intensity of gas exchange characterizes the actual air flow. The intensity of gas exchange refers to internal fires, where the enclosing structures restrict the flow of air into the room, but the openings allow you to determine the amount of air entering the volume of the room.

The intensity or density of smoke, X.This parameter characterizes the deterioration of visibility and the degree of toxicity of the atmosphere in the smoke zone. Visibility loss due to smoke is determined by the density, which is estimated by the thickness of the smoke layer through which the light of the reference lamp is not visible, or by the amount of solid particles contained in a unit volume (g / m 3). Data on the density of smoke generated during combustion substances containing carbon are given below.

There are quite a few parameters of a fire: fire heat, fire size, fire perimeter, flame propagation front, flame radiation intensity, etc.

The concept of fire load.

The main factor determining the parameters of a fire is the type and magnitude of the fire load. Under object fire load understand the mass of all combustible and slow-burning materials per 1 m 2the floor area of ​​the room or the area occupied by these materials on open area:R g .n= , where Р g.n.- fire load; P - mass of combustible and slow-burning materials, kg;F- floor area of ​​the room or open area, m 2.

The fire load of premises, buildings, structures includes not only equipment, furniture, products, raw materials, etc., but also structural elements of buildings made of combustible and slow-burning materials (walls, floors, ceilings, window frames, doors, racks, floors, partitions, etc.).(combustible and slow-burning materials, technological equipment) and temporary (raw materials, finished products).

The fire load of each floor, attic, basement is determined separately. The fire load is taken as follows:

- for residential, administrative and industrial does not exceed 50 kg / m 2, if the main elements of buildings are non-combustible;

- the average value in the residential sector is 27 for 1-room apartments

kg / m 2, 2-room- 30 kg/m 2 , 3-room- 40 kg/m2 ;

- in buildings III fire resistance- 100 kg/m 2 ;

- in industrial premises related to production and processing

combustible substances and materials- 250 - 500 kg/m2 ;

- in the premises where the lines of modern technologicalprocesses and high rack warehouses- 2000 - 3000 kg/m 2 .

For solid combustible materials, it is important structure fire load, i.e. its dispersity and the nature of its spatial distribution (densely packed rows; separate stacks and packs; continuous arrangement or with a break; horizontal or vertical). For example, carton boxes with shoes or rolls of fabric located:

1.horizontally on the floor of a basement warehouse;

2. on warehouse racks with a height of 8- 16 m

give different fire dynamics. In the second case, the fire will spread in 5- 10 times faster.

The degree of sufficient "openness" for combustion depends on the size of the surface of the combustible material, the intensity of gas exchange, etc. For matches, a gap of 3 mm is sufficient for each match to burn from all sides, and for a wooden plate measuring 2000 × 2000 mm, a gap of 10- 15 mm is not enough for free burning.

On practice free consider the surface lagging behind another nearby surface at a distance of 20- 50 mm. To take into account the free surface of the fire load, the coefficient of the combustion surface K p is introduced.

Burning surface coefficient called the ratio of the burning surface areaF n .g to the fire area F n .g .: K n =F p.g. /Fn.

When burning liquids in tanks K n \u003d 1, solid substances K n > 1. For this reason, for the same type of solid combustible material, for example, wood, almost all fire parameters will be different depending on the combustion surface coefficient (burning of logs, boards , shavings, sawdust). For furniture factories I and II degrees of fire resistance) the value of K p ranges from 0.92 to 4.44. For most types of fire load, the value of K p does not exceed 2-3, rarely reaching 4-5.

Burning surface coefficientdetermines the actual value of the burning area, the mass burnout rate, the intensity of heat release in a fire, thermal stress combustion zones, fire temperature, speed of its spread and other parameters of the fire.

Classification of fires and their features

Different types of fires can be classified according to various distinctive features, which include the closedness or openness of the combustion source, the type of aggregate state of the burning substance, and the fire extinguishing agents used. All of them have their own characteristics of origin and development, or the place of a fire, etc. There is no single universal classification of fires. Here are some classifications of fires found in the specialized literature:

I. According to the course of a fire in an open or confined space.

I a . open fires- These are open fires.These include fires at technological installations (distillation columns, sorption towers, installations of the oil, gas, chemical industries), in tanks with flammable liquids, fires in warehouses of combustible substances (wood, solid fuel), forest and steppe fires, fires of grain arrays. Internal fires in buildings and structures can turn into open fires.

The features of open fires include the conditions of heat and gas exchange:

1. there is no accumulation of heat in the combustion zone, since it is not limited to building structures;

2. for the temperature of such fires, the temperature of the flame is taken, which is higher than the temperature of the internal fire, since the temperature of the gaseous medium in the room is taken for it;

3. gas exchange is not limited by the structural elements of buildings, therefore it is more intense, and depends on the intensity and direction of the wind;

4. The zone of thermal influence is determined by the radiant heat flow, since the convective flows go up, creating a rarefaction zone at the base of the fire and providing intensive airflow fresh air, which reduces the thermal effect;

5. The smoke zone, with the exception of peat burning, over large areas and in the forest does not create difficulties in fighting open fires.

These features of open fires determine the specifics of the methods of fighting them, the techniques and methods used to extinguish them.

The open type includes fires, called fire storms, which are a thermal high-temperature vortex

16. Internal fires occur in closed "closed" spaces: in buildings, aircraft cabins, in the holds of ships, inside any units. Here, sometimes, so-called anaerobic fires are separately distinguished, i.e. without air access. The fact is that there are a number of substances (nitrated cellulose, ammonium nitrate, some rocket fuels) that, when the temperature rises, undergo chemical decomposition, leading to the glow of a gas barely distinguishable from a flame.

Internal fires, in turn, are divided into two classes according to the method of distribution of the fire load:

- the fire load is unevenly distributed in a large volume room;

- the fire load is distributed evenly over the entire area.

II. According to the state of aggregation of the combustible substance. Distinguish between fires caused by the combustion of gas, liquid, solid matter. Their combustion can be homogeneous or heterogeneous, i.e. when the fuel and oxidizer are in the same or different states of aggregation.

III. According to the speed of propagation of the burning zone on the fire: deflagration(slow) propagation of the combustion zone (velocity from 0.5 to 50 m/s) and detonation (explosive) propagation of the combustion zone with a shock wave velocity from several hundred m/s to several km/s.

IV. According to the type of the initial stage of the fire: self-ignition (self-ignition) of combustible substances and forced (forced) ignition. In practice, the second type of fire occurs more often.

V. By the nature of the combustible medium and the recommended extinguishing agents. AT In accordance with the International Standard, fires are divided into 4 classes: A, B, C, D , within which subclasses are distinguished Al, A 2 etc. It is convenient to present this in tabular form.

VI. According to the degree of complexity and danger firehe is assigned a number (or rank). Number or rank- a conditional numerical expression of the amount of forces and means involved in extinguishing a fire in accordance with the departure schedule or the plan for attracting forces and means.

The number of call numbers depends on the number of units in the garrison. The schedule should provide for the rapid concentration of the required (calculated) amount of forces and means on a fire with a minimum number of numbers.

At fire no. 1 the guard on duty in full force goes to the area where the fire department is serviced, as well as to objects that have their own fire departments, to all places of accidents, natural disasters, where there is a danger to human life, a threat of explosion or fire.

By fire number 2 send three additional- four squads (depending on how many arrived under No. 1) on tankers and autopumps, as well as special services squads. As a rule, guards on duty in the area of ​​​​departure of neighboring fire departments go to the fire in full force.

In garrisons with 10- 12 fire departments, no more than three ranks fire, where the most appropriate is such an order in which for each additional number, starting from the second, four went to the fire- five branches on the main fire trucks. When determining the number of fire departments leaving for a fire at the highest number, some reserve should be provided in the garrison in case of a second fire. In small garrisons, this reserve can be created by introducing into the combat crew of reserve fire equipment with personnel free from duty.

More numbers ( 4 and 5) established in large garrisons. When scheduling the departure of units according to elevated fire numbers, the condition of roads and passages to individual areas of departure is taken into account. For example, on bad roads, the number of forces leaving on No. 2 or 3 is increased and directed from different directions. Additional tank trucks and hose trucks are sent to areas with insufficient water supply. For some of the most important and fire-hazardous facilities, where a rapid development of a fire and a threat to people's lives is possible, it is planned to send forces and means to an increased fire number at the first message. The list of such objects includes important industrial enterprises or separate buildings, workshops with fire hazardous production processes, warehouses for flammable liquids and gases, material assets, children's and medical institutions, clubs, cinemas, high-rise buildings and separate buildings of public organizations at the discretion of the head of the fire department.

For some objects, an increased number may not be applied upon the first message about a fire, and for fire No. 1, two additional- three squads from fire departments in main or special vehicles.

Applications are made to the schedule of departures, which list:

- objects to which forces are sent according to increased fire numbers;

- waterless sections of the city, to which tank trucks and hose cars are additionally directed;

- multi-storey buildings, to which, at the first report of a fire, additional ladders, car lifts, GDZS cars, smoke exhaust stations are sent.

The number of special vehicles and their type are determined depending on the characteristics of the object. For example, when extinguishing a fire at an oil depot, it is envisaged that foam or powder extinguishing vehicles will leave; in the buildings of museums, libraries, book depositories- carbon dioxide extinguishing vehicles and GDZS; in high rise buildings- ladders, car lifts, GDZS cars, smoke exhaust stations.