What Are The Flame Retardant Grades Of Heat Shrinkable Tubes?

- Sep 11, 2019-

The flame retardant grade of heat shrinkable tube is in UL standard, and there is VW-1 test standard.

UL, VW-1 test standard is a common standard. The test stipulates that the sample should be kept vertical, burned for 15 seconds with a test spray lamp (flame height 125 mm, thermal power 500 W), then stopped for 15 seconds and repeated five times.

The qualified standard of flame retardant grade VW-1 for heat shrinkable tubes is: 1. Flame spread should not exceed 60 seconds. 2. Samples should not burn more than 25%. 3. Surgical cotton pads on the bottom should not 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 is the most widely used standard for flammability of plastic materials. It is used to evaluate the material's ability to extinguish after being ignited. There are many evaluation methods according to the burning speed, burning time, anti-dropping ability and whether droplets are burned or not. Many values can be obtained for each material tested according to its color or thickness. When the material of a product is selected, its UL grade should meet the thickness requirement of plastic parts. UL grade should be reported together with thickness value. It is not enough to report UL grade only without thickness.

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

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

V-2: After two 10-second combustion tests on the sample, the afterglow-afterglow is extinguished in 60 seconds. Dropping particles can ignite cotton.

V-1: After two 10-second combustion tests on the sample, the afterglow-afterglow is extinguished in 60 seconds. Dropping particles do not ignite cotton.

V-0: After two 10-second combustion tests on the sample, the residual flame-afterburning is extinguished in 30 seconds. Dropping particles do not ignite cotton.

5VB: After five five five-second combustion tests on the sample, the afterglow-afterglow is extinguished in 60 seconds. Dropping particles do not ignite cotton. Block samples are allowed to burn through.

5VA: After five five five-second combustion tests on the sample, the afterglow-afterglow is extinguished in 30 seconds. Dropping particles do not ignite cotton. Burn-through is not allowed for bulk samples.

Wire combustion mode in UL1581:

1. VW-1: Vertical Combustion Test (UL Wire Combustion Level);

2. FT1: Vertical combustion test;

3. FT2: Horizontal combustion test;

4. FT4: Vertical combustion test;

5. FT6: Horizontal Combustion and Smoke Test (FT Class is CSA Standard Wire Combustion Class);

In the above level:.VW-1 and FT1 are the same level. FT2 is the easiest to pass and the lowest level.

VW-1 is stricter than FT1, both of which are vertically burned. The criteria are as follows: 1. The burning mark (kraft paper) can not be carbonized more than 25%; the burning duration of 2 or 5 15 seconds can not exceed 60 seconds; 3. The burning droplets can not ignite cotton; VW-1 meets the requirements of 1, 2 and 3; FT1 only meets the requirements of 1 and 2.

For the wire industry, UL94's V-2, V-1, V-0, 5VA, 5VB examines the materials used in the wire. When testing, it is necessary to use additional testing materials to prepare standard samples, which will not be marked on the wire. 10.

VW-1, VW-2, FT-1, FT-2 examine the wire itself. After passing the test, the corresponding grade can be identified on the wire. Wire flame retardant is completely different from UL94 flame retardant. For example, an insulating material can pass through UL94 V-0, but not necessarily through VW-1.

In addition, UL94 is the 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 the flame retardant of wires at all; there is no VW-1/FT1 printed on AWM wires and the V0 combustion test in UL94 is very different 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 combustion chamber is also different: VW-1 requires more than 4 cubic meters, while V0 only requires more than 0.5 cubic meters.

5. The number of combustion is also different from 0Gr4OG\x06.

6. Combustion results: V0 requires recording the burning time, while VW-1 does not.

However, the experimental conditions of the 5V stage combustion and VW-1 combustion in UL94 are similar to those of the test method, and are close to each other. Note: Whether VW-1 or UL94 combustion test equipment, we must refer to ASTM 5025 and ASTM 5027, UL1581 and UL94 are only test methods, test equipment requirements must be in accordance with ASTM standards.

Flame retardant grade of heat shrinkable tube: VW-1/FT1 is quite 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 combustion chamber 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. Combustion results: V0 requires recording the burning time, while VW-1 does not!