SN/T 5240-2020Import and export textiles heat release rate determination cone calorimeter method (English PDF)

7.1 Sample humidity control

The samples shall be humidified for at least 24 h in the standard atmosphere specified in GB/T 6529.

7.2 Specimen

7.2.1 The size of a single sample is 100 mm × 100 mm.

7.2.2 Three single samples are superimposed to form a combined sample.

7.2.3 Under any irradiance, prepare 3 combined samples for parallel testing.

7.3 Sample installation

7.3.1 Wrap the humidity-conditioned combined sample with a single-layer aluminum foil with a thickness of 0.025 mm ~ 0.04 mm, with the glossy surface of the aluminum foil facing the sample;

The aluminum foil should be cut in advance so that it can cover the bottom and sides of the sample and extend beyond the upper surface of the sample by at least 3 mm; the sample should be placed on the aluminum in the middle of the foil, wrap the bottom and sides of the foil, and cut off the excess aluminum foil so that the aluminum foil does not exceed 3 mm of the upper surface of the sample.

7.3.2 The composite sample covered with aluminum foil is placed on the positioning frame as shown in Figure A.3.

a) Place the positioning frame upside down on a flat surface and put it into the grid (see Figure B.1);

b) Put the combined sample covered with aluminum foil into the positioning frame with the test side facing down

c) Put a refractory fiber layer (density 65 kg/m3) on the top, just beyond the edge of the positioning frame;

d) Place the sample mounting frame (see Figure A.2) on top of the refractory fiber layer, install it into the positioning frame, and press it tightly;

e) Place the positioning frame on the sample mounting frame.

8.1 Safety measures

Take appropriate precautions for safety protection. In the combustion test, the test sample may emit toxic and harmful gases when exposed to the radiation cone, and with high temperature and burning, operators should wear protective masks and protective gloves.

8.2 Test preparation

8.2.1 Check the CO2 filter and moisture filter, and replace the adsorbent if necessary. Drain the condensed water in the cold trap, and the normal operation of the cold trap the temperature does not exceed 4 °C.

8.2.2 Adjust the distance between the lower surface of the radiation cone and the upper surface of the sample to (25 ± 1) mm.

8.2.3 Turn on the power of the radiation cone, fan, gas analyzer, weighing equipment and pressure sensor.

8.2.4 Adjust the exhaust flow of the fan to (0.024±0.002) m3/s.

8.2.5 Calibrate the instrument as prompted and record the instrument calibration constant C.

8.2.6 Adjust the radiation illuminance.

Note. When the radiant illuminance is not clearly specified, the radiant illuminance of 25 kW/m2, 35 kW/m2, 50 kW/m2 corresponds to small, medium, and large fires respectively.

Line test.

8.3 Test

8.3.1 Place the sample prepared in 7.3 on the weighing device, and record the mass of the sample before the test to the nearest 0.01 g.

8.3.2 Test the oxygen mole fraction value with an oxygen analyzer, test once every 5 s, and take the average value of the oxygen mole fraction in 60 s as the initial value

8.3.3 Move into the igniter, according to the type of shielding layer (see A.2), remove the radiation shielding layer according to the following regulations, and test the oxygen mole fraction Real-time value

a) Water-cooled shielding layer, remove the shielding layer, move in and turn on the igniter at the same time, and start the test.

b) Non-water-cooled shielding layer, remove the shielding layer within 10 s after moving into the igniter, turn on the igniter while removing the shielding layer, and start test.

8.3.4 When the flame appears, record the time it, turn off and remove the igniter. If the flame goes out after the igniter is turned off, move to the ignition again at the same time, open the igniter and keep the igniter in working condition to maintain combustion until the end of the test. Record the above situation in the test report.

8.3.5 In any of the following cases, end the test and record the remaining mass em of the sample to the nearest 0.01 g.

a) Return to the oxygen mole fraction value before the test for 10 min;

b) The mass of the sample becomes zero;

c) The sample has not been ignited within 30 minutes;

d) Continue to burn for 30 minutes.

8.3.6 Remove the test sample.

8.3.7 Repeat the above steps to test another 2 combined samples.

9.1 Heat release rate per unit area

Calculated by formula (1).