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    Heat-shrink tubing UL standard
    Time: 2018-12-07 13:53:12     Copyfrom: Volsun

    Heat-shrink tubing is not an important device in electronics, but it is often the key to the success of the entire design.The main function of the heat shrink tube in the circuit is to protect important devices and circuits from damage and influence, and to provide insulation, sealing, protection, and aesthetic decoration. In this paper, the flame retardant knowledge of heat shrinkable tubes with less and scattered heat are sorted and summarized.Today we introduce the heat-shrinkable tube flame retardant grade is in the UL standard has the VW-1 test standard.

    UL, VW-1 test standard is a relatively common standard. The experiment stipulated that the sample was kept vertical, and it was burned for 15 seconds with a test torch (flame height 125 mm, heat power 500 W), then stopped for 15 seconds, and repeated 5 times.

    The heat-shrinkable tube flame-retardant grade VW-1 level of eligibility criteria is: 1, the flame spread can not exceed 60 seconds. 2. The sample can not be burned more than 25%. 3. Surgical cotton padded at 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 rating is the most widely used flammability performance standard for plastic materials. It is used to evaluate the ability of a material to extinguish after it has been ignited. There are various evaluation methods depending on the burning speed, burning time, drip resistance, and whether the beads are burned. Each material to be tested can get many values depending on the color or thickness.When a material of a product is selected, its UL rating should meet the thickness requirements of the plastic part.The UL rating should be reported along with the thickness value. It is not enough to report only the UL rating without 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 rating in the UL94 standard.For samples from 3 to 13 mm thick, the burning speed is less than 40 mm per minute; for samples less than 3 mm thick, 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 burn tests on the sample, the afterflame & afterburning is extinguished within 60 seconds. The dripping particles can ignite the cotton.

      V-1: After two 10 second burn tests on the sample, afterflame & afterburning was extinguished within 60 seconds. The dripping particles do not ignite cotton.

      V-0: After two 10 second burn tests on the sample, afterflame & afterburning is extinguished within 30 seconds. The dripping particles do not ignite cotton.

      5VB: After five times and five seconds of burning test on the sample, afterflame & afterburning is extinguished within 60 seconds. The dripping particles do not ignite the cotton. For the bulk sample, it is allowed to be burned through.

      5VA: After five times of 5 seconds of burning test on the sample, afterflame & afterburning was extinguished within 30 seconds. The dripping particles do not ignite cotton. It is not allowed to be burned through for block samples.


    Volsun focus on heat shrink tube, cold shrink tube, silicone tube and some special insulation tube manufacture for over 12 years in China. We are looking forward to establish long term relationship with you and your esteemed company.

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