JZD Wire & Cable Factory
More Than 20 Years Experience
More Than 20 Years Experience
Author: Joey Wan 
January 07,2021
Bundle flame retardant (ZA, ZB, ZC, ZD) test standards are respectively GB/T18380.33~36, which are mainly used to evaluate the ability of vertically installed bundled wires and cables or optical cables to inhibit the vertical spread of flame under specified conditions. A summary of the regulations for each flame retardant category is shown in the attached table.
Different Types of Bundled Flame Retardant Test Requirements
| Flame retardant category | Applications | Sample non-metallic material volume content (L/m) | Fire time (min) | Qualified index | Experiment Method |
| A | Evaluation of high volume content of non-metallic materials | 7 | 40 | The carbonization range on the sample should not exceed 2.5 m above the bottom edge of the torch | GB/T 18380.33 |
| B | Evaluation of the volume content of medium non-metallic materials | 3.5 | 40 | GB/T 18380.34 |
|
| C | Evaluation of low volume content of non-metallic materials | 1.5 | 20 | GB/T 18380.35 |
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| D | Small cable with very low volume content of non-metallic materials | 0.5 | 20 | GB/T 18380.36 |
It can be seen from the standard inspection that none of the relevant standards for bundled flame retardancy gives the definition of the level, but uses the category as the code, such as category A, category B, category C and category D, and there is no clear or implied test for different categories. The grade of the product's flame retardant performance assessment. The description is suitable for occasions with different volume content of non-metallic materials.
In addition, GB 31247-2014 "Cable and Optical Cable Combustion Performance Classification", which is familiar to the wire and cable industry, clearly specifies the combustion performance level specified by the standard. For example, B1 belongs to flame retardant level 1, and B2 belongs to flame retardant level 2. The qualification indicators of different flame retardant categories in the GB/T 18380.33~36 standard are: "The carbonization range on the sample should not exceed 2.5m above the bottom edge of the blowtorch". The difference is that the GB 31247-2014 grade B1 and As different levels, B2 level also has significant differences in the setting of judgment indicators.
According to the standard analysis, it can be seen that the bundled flame retardant (ZA, ZB, ZC, ZD) categories are mainly different in the applicable assessment occasions, not the level of flame retardant performance or the level, and there is no level in the standard setting Level relationship.
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