The flame retardant grade of heat shrinkable tubing is in the UL standard, and there is a VW-1 test standard:

UL, VW-1 test standard is a relatively common standard. The experiment stipulates that the sample should be kept vertical, and burned for 15 seconds with a test blowtorch (flame height 125mm, thermal power 500W), then stop for 15 seconds, repeat 5 times .

The qualified standard for flame retardant grade VW-1 of heat shrink tubing is as follows: 1. The flame spread should not exceed 60 seconds. 2. The sample should not be burned more than 25%. 3. The surgical cotton pad at the bottom cannot be ignited by falling objects.

There are 12 kinds of UL94**************** in the flame retardant grade: HB, V-0, V-1, V-2, 5VA, 5VB, VTM-0, VTM -1, VTM-2, HBF, HF-1, HF-2.

Flammability UL94 ratings are the most widely used standards for the flammability of plastic materials. It is used to evaluate the ability of a material to extinguish after being ignited. According to the burning speed, burning time, anti-dripping ability and whether the dripping beads burn, there are many evaluation methods. Each measured material can have many values depending on color or thickness. When selecting a material for a product, its UL rating should meet the thickness requirements of the plastic parts. The UL rating should be reported together with the thickness value, it is not sufficient to report the UL rating without the thickness.

The flame retardant grade of plastic is gradually increased from HB, V-2, V-1, V-0, 5VB to 5VA:

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

V-2: After two 10-second combustion tests on the sample, the afterflame & afterflame were extinguished within 60 seconds. Dripping particles can ignite cotton.

V-1: After two 10-second combustion tests on the sample, afterflame & afterflame extinguished within 60 seconds. Dripping particles must not ignite cotton.

V-0: After two 10-second combustion tests on the sample, afterflame & afterflame extinguished within 30 seconds. Dripping particles must not ignite cotton.

5VB: After five 5-second combustion tests on the sample, the afterflame & afterflame extinguished within 60 seconds. The dripping particles cannot ignite the cotton. It is allowed to burn through for lumpy samples.

5VA: After five 5-second combustion tests on the sample, the afterflame & afterflame extinguished within 30 seconds. Dripping particles must not ignite cotton. Burn-through is not allowed for blocky samples.

The wire burning method in UL1581:

1. VW-1: vertical burning test (UL wire burning level);

2. FT1: vertical burning test;

3. FT2: horizontal combustion test;

4. FT4: vertical burning test;

5. FT6: Horizontal burning and smoke test (the burning level of FT is the burning level of wires in CSA standard);

Among the above grades: .VW-1 is the same grade as FT1. FT2 is the easiest to pass and has the lowest rank.

VW-1 is stricter than FT1, both of which are vertical combustion, judging criteria: 1. The burning mark (kraft paper) cannot be carbonized more than 25%; 2. The burning time of 5 times of 15 seconds cannot exceed 60 seconds; 3. Burn Drops cannot ignite cotton; VW-1 requires 1, 2, 3 to be met; FT1 only requires 1, 2 to be met.

For the electric wire industry, V-2, V-1, V-0, 5VA, and 5VB of UL94 assess the materials used in the electric wires. During the test, standard samples must be made with the test materials and will not be marked on the electric wires.

VW-1, VW-2, FT-1, and FT-2 assess the wire itself. After passing the test, the corresponding grade can be marked on the wire. The flame retardancy of wires is completely different from the flame retardancy of UL94. For example, an insulating material can pass V-0 of UL94 but not necessarily VW-1;

In addition, UL94 is flame retardant of insulating materials, and the flame retardant requirements of wires are generally on UL758621581; so the flame retardant in UL94 such as V-0, V-1 is not flame retardant of wires at all; there is no printing on AWM wire V0 combustion test in VW-1/FT1 and UL94 has a big difference in equipment:

1. The height and temperature of the flame are different;

2. The methane flow rate used in the test is also different;

3. The back pressure of methane is also different;

4. The volume of the combustion box is also different: VW-1 requires more than 4 cubic meters, while V0 only requires more than 0.5 cubic meters;

5. The burning times are also different 0Gr4OG\x06;

6. In the combustion results: V0 requires recording the residual burn time, but VW-1 does not.

However, the test conditions and test methods of the 5V level combustion and VW-1 combustion in UL94 are similar and relatively close. Note: Whether it is VW-1 or UL94 combustion test equipment, it must refer to ASTM5025 and ASTM5027, UL1581 and UL94 are only test methods, and the requirements of test equipment must be in accordance with ASTM standards.

Flame retardant grade of heat shrink tubing: VW-1/FT1 is very different from V0 combustion test in UL94:

1. The height and temperature of the flame are different;

2. The methane flow rate used in the test is also different;

3. The back pressure of methane is also different;

4. The volume of the combustion box is also different: VW-1 requires more than 4 cubic meters, while V0 only requires more than 0.5 cubic meters;

5. The burning times are also different;

6. In the combustion results: V0 requires recording the residual burn time, but VW-1 does not.