Horizontal flammability tester sampling principle test procedure

The horizontal flammability tester is used to test the relative burning rate and flame retardancy of textiles, especially automotive upholstery fabrics, and is a test device developed and produced by Shanghai Qianshui Precision Electromechanical Technology Co.

Testing principle.

The specimen is clamped horizontally on a U-shaped stand and the free end of the specimen is ignited in the combustion chamber with a prescribed height flame for 15s to determine whether or when the flame on the specimen is extinguished, and the distance the specimen burns and the time spent burning that distance.

Test specimens.

1. Shape and size

Standard specimen shape and dimensions. The thickness of the specimen shall be the thickness of the part, but not more than 13 mm. when comparing the burning properties of different types of material, the specimens must have the same dimensions (length, width and thickness). Usually the sample must be taken so that it has the same cross-section along its entire length. When the shape and dimensions of the part are not sufficient to make a standard specimen of the specified size, the following small size specimens should be secured, but recorded.

a) If the width of the part is between 3mm and 60mm, the length should be at least 356mm. in this case the specimen should be made as close to the width of the part as possible.

b) If the width of the part is greater than 60 mm, the length should be at least 138 mm, where the possible burning distance corresponds to the distance from the marker line to the time when the flame is extinguished or from the beginning of the bar marker line to the end of the specimen.

c) If the width of the part is between 3mm ~ 60mm, and the length is less than 356mm or the width of the part is greater than 60mm, the length is less than 138mm, it can not be tested according to this standard; width of less than 3mm specimen also can not be tested according to this standard.

2. Sampling

At least 5 specimens should be taken from the part under test. If there are materials with different burning rates along different directions, the specimens should be intercepted in different directions and five (or more) specimens should be tested separately in the combustion chamber. Sampling is to be carried out as follows.

a) When the material is supplied in full width, a sample containing the full width and at least 500mm in length should be taken, with 100mm from the edge cut off, and then equally spaced and uniformly sampled from each other on the remainder.

b) If the shape and dimensions of the part meet the sampling requirements, the specimen shall be taken from the part.

c) If the shape and size of the part does not meet the sampling requirements, and must be tested in accordance with this standard, the same material and process can be used to produce the same structure and parts of the standard specimen (356mm x l00mm), the thickness of the part to take a small thickness and shall not exceed 13mm for testing. The results of this test cannot be used for identification, certification and other cases, and must be indicated in the test report sample production.

d) If the thickness of the part is greater than 13mm, mechanical methods should be used to cut from the non-exposed surface so that the thickness of the specimen, including the exposed surface, is 13mm.

e) If the thickness of the part is not uniform, mechanical methods should be applied to cut from the non-exposed side so that the thickness of the part is uniform for a small portion of the thickness.

f) If the part bending can not be made flat specimen, should take as much flat part, and the specimen arch height does not exceed 13mm; if the specimen arch height exceeds 13mm, it is necessary to use the same material with the same process to produce the same structure and parts of the standard specimen (356mm x l00mm), the thickness of the part to take a small thickness and shall not exceed 13mm for testing.

g) laminated composite materials should be considered as a single material for testing, sampling methods as above.

h) If the material is made of a number of layers, but does not belong to the laminated composite material, it should be exposed from the surface within 13mm thick all the layers of a single material are sampled separately for testing, material A and material B between the interface is not bonded, material A alone for testing. Material B is within 13mm of thickness and is closely bonded to material C. Therefore, materials B and C should be tested as laminated composites with a cut of 13mm.

Test steps.

1. Remove the pretreated specimen, place the pile or tufted surface flat on a flat table and comb the pile twice along the opposite direction of the pile with a metal comb in accordance with 4.2.5.

2. Light the gas lamp with the air inlet to the gas lamp closed and adjust the flame to a flame height of 38 mm according to the flame height marker plate. the flame should burn steadily for at least 1 min in this condition before starting the test and then extinguish.

3. Fit the specimen into the specimen holder with the exposed side facing downwards. Fit the specimen so that it is held on both sides and one end by the U-shaped holder, with the free end aligned with the opening of the U-shaped holder. Place the specimen on the specimen holder with the heat resistant metal wire for the combustion test only when the specimen is not wide enough for the U-shaped holder to hold the specimen, or when the free end of the specimen is soft and bends easily causing unstable combustion.

4. Push the specimen holder into the combustion chamber and place the specimen in the centre of the chamber in a horizontal position. Ignite the gas lamp with the gas lamp air inlet closed and make the flame height 38mm so that the free end of the specimen is in the flame for 15s and then extinguish the flame (close the gas lamp valve).

5. The flame burns forward from the free end of the specimen and starts timing the moment the root of the spreading flame passes the marker. Observe the flame propagation on the faster burning side and time the flame propagation on the faster side.

6. When the flame reaches the second marker or when the flame is extinguished before reaching the second marker, the timing is stopped at the same time and the timing is also based on the side with the faster propagating flame. If the flame is extinguished before reaching the second mark, the distance from the mark to the time the flame is extinguished is measured. The burning distance is the length of the part of the specimen that has burned on the surface or inside.

7. If the non-exposed side of the specimen has been cut, the flame propagation speed of the exposed side shall be used for timing purposes.

8. The requirement for burning speed does not apply to the surface formed by cutting the specimen.

9. If the specimen burns slowly for a long time from the start of the timing, the test may be stopped at 20 minutes into the test and the burning time and burning distance recorded.