UL94HB flame retardant grade test and requirements

The flame retardant grades of plastics increase gradually from HB, V-2, V-1 to V-0:

1. HB: The lowest flame retardant grade in the UL94 standard. It is required that for samples with a thickness of 3 to 13 mm, the burning rate is less than 40 mm per minute; for samples with a thickness of less than 3 mm, the burning rate is less than 70 mm per minute; or extinguished before the 100 mm mark.

2. V-2: After two 10-second burning tests on the sample, the flame goes out within 60 seconds. There may be burning objects falling.

3. V-1: After two 10-second burning tests on the sample, the flame goes out within 60 seconds. No burning objects should fall.

4. V-0: After two 10-second burning tests on the sample, the flame goes out within 30 seconds. No burning objects should fall.

UL94 standard test procedures and requirements:

(1) UL94HB

Sample: 5"×1/2"×thickness (typical thickness is 1/16", 1/8", 1/4")

Test steps:

There are three samples of each thickness to be tested. Before the test, the samples are placed under the conditions of 20℃ and 50%RH for 48 hours. The sample should be placed parallel to the long axis and at a 45-degree angle to the short axis. For each sample, draw two lines 1" and 4" from one end.

Place a 1" blue flame on the end of the sample that is suspended in the air, burn for 30 seconds and then remove it. If the sample continues to burn after the flame is removed, measure the time the sample burns between the two width marks, and The burning rate is calculated in inches per minute.

Level requirements: UL94HB

(1) For samples with a thickness between 0.120" and 0.500", the span cannot exceed 1.5" per minute and greater than 3.0".

(2) For samples with a thickness of 0.120", the span cannot exceed 3.0".

(3) The sample will spontaneously ignite when the flame does not touch the 4.0" mark.