VIT 311 – Horizontal Flammability Tester

Testing Method

Test Principle
A sample is held horizontally in a U-shaped holder and exposed to a defined low-energy flame for 15 seconds in a combustion chamber. The flame acts on the free end of the sample, and the test determines when the flame extinguishes or how long it takes for the flame to pass a measured distance along the sample.

Sample Preparation

• Prepare five samples from the tested items. If the material burns at different speeds in different directions, each sample should be tested separately in those directions.
• Samples should be 356 mm x 100 mm, with a maximum thickness of 13 mm. If the thickness is greater than 13 mm, it should be mechanically reduced.
• For irregularly shaped articles, flat parts of the article should be used, and if necessary, test samples should be made with the same material and structure as the article.

Test Steps

1. Environmental Conditioning: Samples should be conditioned at 23 ± 2°C and 45% ~ 55% relative humidity for at least 24 hours but not more than 168 hours before testing.
2. Sample Placement: Place the sample in the sample holder with the exposed side facing downward towards the flame.
3. Flame Adjustment: Adjust the gas flame to a height of 38 mm using the mark in the chamber, ensuring the air intake of the burner is closed. The flame should burn for at least 1 minute before starting the test.
4. Testing: Insert the sample holder into the combustion chamber, exposing the end of the sample to the flame. The gas flow should be cut off after 15 seconds.
5. Burning Time Measurement: Measure the time from when the flame passes the first measuring point to when it either reaches the last measuring point or extinguishes.
6. Burning Distance: If the flame does not reach the last measuring point, measure the distance the flame traveled before extinguishing.

Test Results

• A (0 mm/min): No combustion after flame source is extinguished or if the flame extinguishes before reaching the first measuring point.
• B: Flame extinguishes within 60 seconds, with a combustion distance not exceeding 50 mm.
• C: Flame extinguishes between two standard measuring lines and does not meet the criteria for B. The combustion rate is calculated.
• D: Flame reaches the second measuring line. If the burning time is less than 20 minutes, the actual time is recorded; if more than 20 minutes, the time is recorded as 20 minutes.
• E: If the sample burns to the first standard line within 15 seconds of flame ignition, the result is considered unsatisfactory.