The heat-shrinkable tube flame retardant grade is in the UL standard and has the VW-1 test standard.

UL, VW-1 test standard is a relatively common standard. The experiment stipulates that the sample is kept vertical. It is burned for 15 seconds with the test torch (flame height 125mm, heat power 500W), then stopped for 15 seconds, 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 burn 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 obtain 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, 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 and afterburning were extinguished within 60 seconds. The dripping particles do not ignite cotton.

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

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

Wire burning method in UL1581:

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

2, FT1: vertical burning test;

3. FT2: horizontal burning test;

4, FT4: vertical burning test;

5, FT6: horizontal burning and smoke test (FT class burn rating is CSA standard wire burning grade);

In the above levels: .VW-1 is the same level as FT1. The FT2 is the easiest to pass and has the lowest rating.

VW-1 is strictly perpendicular to FT1, both of which are vertical combustion. The judgment criteria are as follows: 1. The combustion mark (kraft paper) cannot be carbonized by more than 25%; the burning time of 2, 5 times and 15 seconds of burning cannot exceed 60 seconds; 3. Burning The drip cannot ignite the cotton; the VW-1 is required to satisfy 1, 2, 3; the FT1 is only required to satisfy 1, 2 .

For the wire industry, UL94's V-2, V-1, V-0, 5VA, and 5VB are used to evaluate the materials used in the wires. When testing, standard samples should be prepared using test materials and will not be marked on the wires. ­

The VW-1, VW-2, FT-1, and FT-2 are the wires themselves. After the test is passed, the corresponding level can be identified on the wires. The flame retardant of the wire is completely different from the flame retardant of UL94. For example, an insulating material can pass the V-0 of UL94 but not necessarily pass the VW-1;

In addition, UL94 is the flame retardant of insulating materials, and the flame retardant requirements of wires are generally on UL758621581; therefore, the flame retardant in UL94 such as V-0, V-1 is not the flame retardant of wires; there is no printing on AWM wires. The V0 combustion test in VW-1/FT1 and UL94 is quite different in equipment:

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

2. The methane flow 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 number of combustion is also different 0Gr4OG\x06;

6. In the burning result: V0 requires recording the residual time, while VW-1 is not used.

However, the test conditions of 5V-class combustion and VW-1 combustion in UL94 are similar to those in the test method. Note: Regardless of whether it is VW-1 or UL94 combustion test equipment, it must refer to ASTM5025 and ASTM5027. UL1581 and UL94 are only test methods. The requirements of test equipment must be in accordance with ASTM standards.

Heat-shrinkable tube flame retardant grade: VW-1/FT1 is very different from UL94's V0 burn test:

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

2. The methane flow 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, and V0 only requires more than 0.5 cubic meters;

5. The number of combustions is also different;

6. In the burning result: V0 requires recording the residual time, while VW-1 is not used!

热缩管的阻燃等级有哪些？
热缩管阻燃等级在UL标准中，有VW-1测试标准。
UL，VW-1测试标准是较为常见的一种标准，实验规定试样保持垂直，用试验用的喷灯(火焰高度125mm，热功率500W)燃烧15秒钟，然后停止15秒钟，反复5次。
热缩管阻燃等级VW-1级别合格标准为：1、火焰蔓延不可超过60秒钟。2、试样不可烧损25%以上。3、垫在底部的外科用棉不可被落下物引燃。
阻燃等级中UL94******************有12种：HB、V-0、V-1、V-2、5VA、5VB、VTM-0、VTM-1、VTM-2、HBF、HF-1、HF-2。
可燃性UL94等级是应用最广泛的塑料材料可燃性能标准。它用来评价材料在被点燃后熄灭的能力。根据燃烧速度、燃烧时间、抗滴能力以及滴珠是否燃烧有多种评判方法。每种被测材料根据颜色或厚度都可以得到许多值。当选定某个产品的材料时，其UL等级应满足塑料零件部分的厚度要求。UL等级应与厚度值一起报告，只报告UL等级而没有厚度是不够的。
塑料阻燃等级由HB、V-2、V-1、V-0、5VB向5VA逐级递增：
HB：UL94标准中最底的阻燃等级。要求对于3到13毫米厚的样品，燃烧速度小于40毫米每分钟;小于3毫米厚的样品，燃烧速度小于70毫米每分钟;或者在100毫米的标志前熄灭。
V-2：对样品进行两次10秒的燃烧测试后，余焰&余燃在60秒内熄灭。滴落的微粒可点燃棉花。
V-1：对样品进行两次10秒的燃烧测试后，余焰&余燃在60秒内熄灭。滴落的微粒不可点燃棉花。
V-0：对样品进行两次10秒的燃烧测试后，余焰&余燃在30秒内熄灭。滴落的微粒不可点燃棉花。
5VB：对样品进行五次5秒的燃烧测试后，余焰&余燃在60秒内熄灭。滴落的微粒不可点燃棉花.对于块状样品允许被烧穿。
5VA：对样品进行五次5秒的燃烧测试后，余焰&余燃在30秒内熄灭。滴落的微粒不可点燃棉花。对于块状样品不允许被烧穿。
UL1581中的电线燃烧方式：
1、VW-1：垂直燃烧测试(UL电线燃烧等级);
2、FT1：垂直燃烧测试;
3、FT2：水平燃烧测试;
4、FT4：垂直燃烧测试;
5、FT6：水平燃烧和烟熏测试(FT类的燃烧等级是CSA标准的电线燃烧等级);
以上级别中：.VW-1与FT1同一个等级。FT2最容易通过，等级最低。
VW-1严格于FT1，二者都是垂直燃烧，判定标准:1、燃烧标记(牛皮纸)不能被炭化超过25%;2、5次15秒的燃烧续燃时间不能超过60秒;3、燃烧滴落物不能引燃棉花;VW-1要求满足1、2、3;FT1只要求满足1、2。
对于电线行业来说，UL94的V-2、V-1、V-0、5VA，5VB考核的是电线所用的材料，测试时要另外用测试材料制定标准样本，不会在电线上标识。­
VW-1，VW-2，FT-1，FT-2考核的是电线本身，测试通过后，可以在电线上标识对应的等级。电线的阻燃跟UL94的阻燃完全是两个不同的东西，打个比方一种绝缘材料能通过UL94的V-0但不一定就能通过VW-1;
另外UL94是绝缘材料的阻燃，而电线的阻燃要求一般是在UL758621581上;所以V-0，V-1等UL94里面的阻燃根本就不是电线的阻燃;在AWM线材上就没有印VW-1/FT1与UL94中V0燃烧试验在设备就有很大区别：
1、火焰的高度与温度就不同;
2、测试时所用的甲烷流量也不同;
3、甲烷的背压力也不同;
4、燃烧箱的体积也有区别：VW-1要求大于4立方，而V0只要求大于0.5立方便可;
5、燃烧次数也不同0Gr4OG\x06;
6、燃烧结果中：V0要求记录残灼时间，而VW-1则不用。
但UL94中的5V级燃烧与VW-1燃烧的试验条件与试验方法差不多，比较接近。注意：不管是VW-1还是UL94燃烧试验设备，都得参照ASTM5025与ASTM5027，UL1581与UL94只是试验方法，试验设备的要求一定要按ASTM标准。
热缩管阻燃等级：VW-1/FT1 与 UL94中V0燃烧试验有很大区别：   
1、火焰的高度与温度就不同；
2、测试时所用的甲烷流量也不同；
3、甲烷的背压力也不同；
4、燃烧箱的体积也有区别：VW-1要求大于 4立方，而V0 只要求大于0.5立方便可；
5、燃烧次数也不同；
6、燃烧结果中：V0要求记录残灼时间，而VW-1则不用！