Judgment of protective performance of arc protective clothing

The common problem in the field of arc protective clothing is: whether the arc grade ATPV value or the arc grade EBT value can better reflect the protective performance of clothing. The United States has decades of protection experience in the field of arc protection, so the ATPV value and EBT value are briefly introduced and analyzed with reference to the relevant American standards and foreign materials

while astmf1959, a method for testing the arc level of clothing materials, was still in its infancy, astmf18 Committee (Committee on electrical protective equipment for workers of the American Society for experimental materials) recognized that some materials can make the skin feel a burning warning before the material breaks, while other materials can’t. Therefore, two rating standards were initially produced: one is ATPV, the thermal performance value of arc; The other is EBT, the threshold energy of material rupture

an enterprise once divided the two in the early stage of its market, because the materials they tested did not have “burst” phenomenon. This conclusion is arbitrary, because experiments since then have shown that each fiber breaks before it reaches the predicted level of combustion. Now, we find that knitted fabrics usually burn before the burning point, while woven fabrics burn before the breaking point. Each fabric structure and fiber has its own advantages and disadvantages

there are two reasons for the committee to rename the arc level: one is to simplify the professional terms on the label so that the end users can better understand it, and the other is to eliminate the misunderstanding of EBT. From many aspects, the Committee retained the EBT and ATPV values as a label or appendix in the arc grade, which is of great significance for more professional and safe use of arc protective clothing. So now we can see that the anti arc clothing labels are marked with ATPV = xcal / cm2 or EBT = xcal / cm2

the fabric marked with EBT value does not show second degree burn on the calorimetric sensor in most cases, because the tiny cracks on the fabric are not directly located on the sensor. 1n theory, if these cracks and holes are directly located on the sensor, there will be a burn prediction where the cracks and holes are, so it can be rated directly. Both arc levels are measured in cal / cm2 and the minimum value is usually recorded. 1n other words, EBT value or ATPV value can be recorded, but only one is selected as the arc rating of fabric. According to ASTM f1506 (Standard Performance Specification for textile materials used in protective clothing for electrical workers exposed to transient arc and related thermal hazards), only the minimum value can be written on the clothing label

if the arc grade of clothing is evaluated according to astmf1506 standard, the fabric must go through several tests, such as washing test and astmd6413 vertical combustion test. 1n other words, in order to achieve flame retardancy under arc, flash or any flame conditions, fabrics must meet a series of or more comprehensive tests

according to ASTM standard, the two indexes of arc grade are as follows:

ATPV value is based on Stoll curve. The energy incident on the material has 50% possibility to make enough heat penetrate the sample to cause second degree burn

the EBT value is the energy incident on the material, which has a 50% probability of fracture. When the total area of the holes on the fabric exceeds 1.6cm2, it is considered to be broken

both ATPV and EBT are evaluated by the same test method (astmf1959), but the arc level is recorded by the first value. 1f the thermal insulation value of the material is greater than the arc tensile strength, the material will break first; Otherwise, it will burn before it breaks

if the EBT value is equal to or less than the ATPV value, “EBT” will be taken as the arc grade value and marked as the arc grade (EBT); 1f the EBT value is greater than the ATPV value, “ATPV” will be taken as the arc grade value and marked as the arc grade

China labor insurance net

Back to list