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Smoke production coefficient. Determination of smoke-generating ability Smoke production coefficient GOST


Smoke-generating ability - the ability of substances and materials to emit smoke during combustion or thermal decomposition.

According to part 9 of article 13 Federal law No. 123-ФЗ dated July 22, 2008 " Technical regulations about the requirements fire safety»According to their smoke-generating ability, combustible building materials, depending on the value of the smoke production coefficient, are divided into the following groups:

  1. With low smoke generating ability (D1), having a smoke production coefficient of less than 50 square meters per kilogram
  2. With a moderate smoke-generating ability (D2), having a smoke production coefficient of at least 50, but not more than 500 square meters per kilogram
  3. With a high smoke-generating ability (DZ), having a smoke production coefficient of more than 500 square meters per kilogram

In accordance with Table 27 of Federal Law No. 123-FZ of July 22, 2008 "Technical Regulations on Fire Safety Requirements" a number of building materials must be tested to determine the smoke production coefficient. Such materials include finishing and facing materials for walls and ceilings, including paints, varnish enamels, flooring materials, floor carpets and thermal insulation materials.

The essence of the method is based on the property of attenuation of the flux of light (illumination) when passing through a layer of smoke formed as a result of thermal decomposition or combustion of solid materials and substances. The amount of attenuation of the luminous flux is recorded using a photometric system.

For testing in the FGBU SEU FPS IPL in the Republic of Mordovia, it is necessary to provide 10-15 samples of the test material with a size of 40 × 40 mm and an actual thickness, but not more than 10 mm (for foam samples, a thickness of up to 15 mm is allowed). Paintwork and film coatings are tested applied on the same substrate as in the actual design. If the area of ​​application of varnishes and paints is unknown, then they are tested applied to aluminum foil 0.2 mm thick.

Prepared samples before testing are kept at a temperature of (20 ± 2) ° С for at least 48 hours, then weighed with an error of not more than 0.01 g. Samples should characterize the average properties of the material under study.

Testing of samples is carried out in a thermophysical laboratory at the "Dym" testing facility.

Scheme of the "Smoke" installation for determining the smoke production coefficient of solids and materials
1 - combustion chamber; 2 - sample holder; 3 - quartz glass window; 4, 7 - blowdown valves; 5- light receiver; 6 - measurement chamber; 8 - quartz glass; 9 - light source; 10 - safety membrane; 11 - fan; 12 - guiding visor; 13 - ignition burner; 14 - insert; 15 - electric heating panel.

Installation appearance

Testing of samples is carried out in two modes: in a smoldering mode and in a combustion mode using a gas burner. In each mode, five samples are tested.

The results are processed according to the GOST 12.1.044-89 method.

The smoke production coefficient Dm in m 2 kg -1 is calculated by the formula:

where V is the capacity of the measurement chamber, m3; L is the length of the path of the light beam in a smoky environment, m; m is the mass of the sample, kg; T0, Tmin - respectively the values ​​of the initial and final light transmission,%.

For each test mode, the smoke production coefficient is determined as the arithmetic mean of the results of five tests.

The smoke production coefficient of the test material is taken as greater importance smoke production coefficient calculated for two test modes.

After testing and paying for the cost of the test, the employees of the test fire laboratory prepare reporting documentation.

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Testing

Place the sample in the holder, fix its position using the fixing devices, place the holder with the sample on the platform and introduce it into the chamber.

Close the cell door and start the stopwatch. After holding for 2 min, the burner flame is brought into contact with the sample at point "0" located along the central axis of the sample. Leave the flame in this position for (10 ± 0.2) min. After this time, return the burner to its original position.

If the sample has not ignited within 10 minutes, the test is considered complete.

In the event of ignition of the sample, the test is completed when the flame combustion stops or after 30 minutes have elapsed from the start of exposure to the sample with a gas burner by forced extinguishing.

During the test, the ignition time and the duration of the flame combustion are recorded.

Measure the length of the damaged part of the sample along its longitudinal axis for each of the five samples. Measurements are carried out with an accuracy of 1 mm.

Damage is considered to be the burnout and carbonization of the sample material as a result of the spread of flame combustion over its surface. Melting, warping, sintering, swelling, shrinkage, change in color, shape, violation of the integrity of the sample (ruptures, surface chips, etc.) are not damage.

The flame propagation length is determined as the arithmetic mean over the length of the damaged portion of five samples.

The value of KPPTP is established on the basis of the results of measuring the length of flame propagation

Smoke production coefficient

Smoke production coefficient is an indicator characterizing the optical density of smoke formed during flame combustion or thermal oxidative destruction (smoldering) of a certain amount of solid matter (material) under special test conditions.

The value of the smoke production coefficient should be used to classify materials according to their smoke generating ability. There are three groups of materials:

with low smoke generating ability - smoke production coefficient

up to 50 m 2 · kg -1 inclusive;

with moderate smoke generating ability - smoke production coefficient

St. 50 to 500 m 2 · kg -1 inclusive;

with high smoke-generating ability - smoke production coefficient

St. 500 m 2 kg -1.

The value of the smoke production coefficient must be included in the standards or technical conditions on solids and materials.

The essence of the method for determining the smoke production coefficient is to determine the optical density of smoke generated during combustion or smoldering of a known amount of a test substance or material distributed in a given volume.


Installation for determining the smoke production coefficient

1 - the combustion chamber; 2 - sample holder; 3 - quartz glass window; 4, 7 - purge valves; 5 - light receiver; 6 - measurement chamber; 8 - quartz glass; 9 - Light source; 10 - safety membrane; 11 - fan: 12 - guiding visor; 13 - ignition burner: 14- liner; 15 - electric heating panel.

For testing, prepare 10 - 15 samples of the test material with a size (40x40) mm and an actual thickness, but not more than 10 mm (for foam samples, a thickness of up to 15 mm is allowed). Paintwork and film coatings are tested on the same substrate as in the actual design. If the area of ​​application of varnishes and paints is unknown, then they are tested applied to aluminum foil with a thickness of 0.2 mm.

Before testing, prepared samples are kept at a temperature of (20 ± 2) ° С for at least 48 hours, then weighed with an error of not more than 0.01 g. Samples should characterize the average properties of the material under study.

Samples are tested in two modes: in the glow mode and in the combustion mode using a gas burner (burner flame length 10 - 15 mm).

The prepared sample is placed in a boat from of stainless steel... The door of the combustion chamber is opened and the boat with the sample is placed in the holder without delay, after which the door is closed.

The test is terminated when the minimum light transmittance is reached.

In the case when the minimum value of light transmission is outside the working range or is close to its boundaries, it is allowed to reduce the length of the path of the light beam (the distance between the source and the receiver of light) or change the dimensions of the sample.

When tested in the smoldering mode, the samples shall not self-ignite. In the case of spontaneous ignition of the sample, subsequent tests are carried out with a value of the heat flux density reduced by 5 kW · m -2. The heat flux is reduced until the specimen ceases to autoignite during the test.

In each mode, five samples are tested.

The smoke production coefficient (D m) in m 2 kg -1 is calculated by the formula

where V- capacity of the measurement chamber, m 3;

L - light beam path length in a smoky environment, m;

m is the mass of the sample, kg;

T 0,T min- respectively, the values ​​of the initial and final light transmission,%.

Smoke production coefficient- This is an indicator characterizing the optical density of smoke formed during the flame or thermo-oxidative destruction () of a certain amount of a solid (material) under special test conditions. The smoke production coefficient is determined by.

Solids (materials) are classified according to their smoke-generating ability according to the data given in the table.

Classification

The smoke production coefficient is used in the fire-prevention regulation of the use of building materials in buildings (structures), to confirm compliance with the requirements specified in the regulatory and technical documentation. The smoke factor value is included in the standards or specifications for solids (materials).

In more detail about the classification of combustible building materials by smoke-generating ability in the material:

The values

Substances and materials Smoke production coefficient, m 2 / kg -1
Smoldering Combustion
Corrugated cardboard – 1
Loose flax – 3,37
Wood 345 23
Decorative atlas 32 32
Cotton – 35
Cardboard brand "G" – 35
Reps 50 50
Lumber hardwood with three layers of varnish PF-283 – 53
Fiber board from the osprey of the Zichevsk paper mill – 54
Tent canvas 57 58
Lumber conifers with two layers of glyphtal oil – 61
Viscose fabric 63 63
Glued plywood + sliced ​​veneer – 69
Butyl alcohol – 80
Chipboard (particle board) 760 90
Glass fiber laminate – 92
Wood fiber (birch, aspen) 323 104
Half-woolen furniture fabric 103 116
Yubileiny tobacco 240 120
Fibreboard (fiberboard) 879 130
Plywood 700 140
Pine 759 145
Birch 756 160
Turbine oil – 243
Gasoline (A-76) – 256
PVC linoleum (TU 21-29-76-79) 200 270
Ethyl acetate – 330
Fiberglass 640 340
PVC film grade PDO-15 640 400
Mipora – 400
Linoleum on a fabric basis – 469
Cyclohexane – 470
Film brand PDSO-12 820 470
Fiberglass polyester fiber sheet – 475
Polyester fiberglass "Sinplex" – 520
Toluene – 562
Diesel fuel – 620
Polyfoam grade PPU-316m – 757
High pressure polyethylene HDPE 1930 790
Rubber (TU 38-5-12-06-68) 1680 850
Polyethylene 1290 890
Expanded polystyrene PS-1 – 1048
Expanded polystyrene PS-1 + 3% decabromo and phenyloxide – 1219
Polyfoam PVC-9 2090 1290

Method of determination

The determination of the smoke production coefficient, and, accordingly, the smoke-generating ability of combustible building materials, is carried out in accordance with the requirements of paragraph 4.18 of GOST 12.1.044-89. The essence of the method for determining the smoke production coefficient is to determine the optical density of smoke generated during combustion or smoldering of a known amount of a test substance or material distributed in a given volume. In other words, the weakening of illumination when light passes through a smoky space is photometrically recorded.

1 - combustion chamber; 2 - sample holder; 3 - quartz glass window; 4, 7 - blowdown valves; 5 - light receiver; 6 - measurement chamber; 8 - quartz glass; 9 - light source; 10 - safety membrane; 11 - fan; 12 - guiding visor; 13 - ignition burner; 14 - insert; 15 - electric heating panel

The figure shows a diagram of the installation for determining the smoke production coefficient. The combustion chamber with a capacity of 3 × 10 -3 m 3 is made of sheet stainless steel with a thickness of 2.0 ± 0.1 mm. It has upper and lower openings with a cross section of 30 × 160 mm, connecting it to the smoke chamber. On the side surface of the combustion chamber, there is a quartz glass window for observing the sample during testing. A sample holder and a closed electric heating panel mounted on the upper wall of the chamber at an angle of 45 ° to the horizontal are installed in the combustion chamber. The sample holder is made in the form of a frame with a size of 100x100x10 mm and is fixed on the chamber door at a distance of 60 mm from the panel parallel to its surface. An asbosilite insert is installed in the holder, in the center of which there is a recess for placing the sample. A gas burner is installed above the sample holder. When testing materials in combustion mode, the burner flame touches the surface of the upper part of the specimen.

The smoke chamber with dimensions 800x800x800 mm is made of stainless steel sheet. The inner walls of the chamber are covered with black paper. In the upper wall and in the bottom of the chamber there are openings for the purge check valves, illuminator and safety diaphragm. Inside the chamber there is a device for vertical movement of the photocell and a two-blade fan for mixing the smoke.

The tests are carried out in two modes: thermal oxidative decomposition (smoldering) and flame combustion. The thermo-oxidative decomposition (smoldering) mode is provided when the sample surface is heated to 400 ° C, while the heat flux density is 18 kW / m 2. Materials, the thermal stability of which is higher than 400 ° C, are tested when heated to 600 ° C, the heat flux density is 38 kW / m 2. In all cases, the materials shall not spontaneously ignite when tested. The flame combustion mode is provided when using a gas burner and heating the sample surface to 750 ° C, while the heat flux density is 65 kW / m 2. To measure the heat flux density, a metal-calorimetric type sensor is used.

When setting up the installation, the voltage supplied to the electric heating panel is determined, which ensures the indicated test modes. To do this, insert an insert with a control sample made of asbestos cement (40x40x10 mm) into the holder, in the center of which a thermocouple is fixed. The combustion chamber door is closed and voltage is applied to the coils of the electric heating panel. A potentiometer is used to control the stabilized heating conditions.

When testing in a flame combustion mode, insert an insert with an asbestos-cement sample into the holder, close both chambers, apply the voltage selected for this mode to the spirals of the electric heating panel. After the panel reaches stabilized heating conditions, the illuminator, the measuring instrument of the lux meter, and the stirring fan are turned on. Then the combustion chamber is opened, the insert with the asbestos-cement sample is taken out, the gas burner is ignited, the chamber is closed. The smoke chamber is purged for 1 min. Adjust the illuminator with the diaphragms, setting the illumination to 100 lux, and the diameter of the light beam equal to the diameter of the photosensitive surface of the photocell. A prepared sample of the test material is placed in an insert at room temperature, the door of the combustion chamber is opened, the insert is inserted into the holder without delay and the door is closed. The duration of the test is determined by the time it takes to reach the minimum illumination, but not more than 15 minutes.

When testing in smoldering mode, the gas burner is not ignited, an insert with an asbestos-cement sample is installed, a corresponding voltage is applied to the electric heating panel. The test procedure is the same as for the flame combustion mode. Five samples of material are tested in each mode. The smoke production coefficient D is calculated from the results of each test. T max by the formula:

D tmax = (V / L× m) ln (E / Emin),

V- capacity of the smoke chamber, m 3;

L- the length of the light path in the smoky space, m;

T Is the mass of the sample of the material under study, kg;

In (E / Emin)- optical density of smoke;

E / Emin- respectively, the initial and minimum illumination, lx.

For each series of tests, calculate the arithmetic mean of at least five values ​​of the smoke production coefficient. The highest value of the two arithmetic means is taken as the final result.

Smoke production coefficient determination protocol can be downloaded.