Testing Method for Physical Protection Performance of Protective Clothing Fabrics
Chemical protective clothing, also known as chemical protective clothing, is protective clothing worn to protect oneself from chemical hazards or corrosive substances. Can cover the whole or most of the human body, at least can provide protection to the torso, arms or thighs. Chemical protective clothing is allowed to be a combination of multiple pieces of clothing with protective functions, and can also be used in conjunction with other protective equipment. In response to emergencies, investigation, rescue, disinfection, disposal of toxic waste, production of chemical substances, agricultural pesticides, medical treatment, spraying and other work, it can effectively protect the human body, so the protective performance of protective clothing is very important. It is very important for users. The country recently promulgated the national standard "GB 24539-2021 Protective Clothing - Summary of Test Items for Chemical Protective Clothing", which stipulates various properties and test methods of protective clothing. The standard will come into effect on September 1, 2022.
According to the protective performance and requirements, there are many kinds of chemical protective clothing. This article introduces the national standard requirements and test methods of airtight chemical protective clothing. Gas-tight chemical protective clothing: a single-piece chemical protective clothing with a hood, windows, and hand and foot protection. When matched with suitable respiratory protective equipment, it can protect against a higher level of toxic and harmful chemicals (gas, liquid, and solid particles) ).
According to the provisions of "GB/T 3923.1 Textiles - Tensile properties of fabrics - Part 1: Determination of breaking strength and elongation at break (strip method)" strip method.
A fabric sample of fixed size is stretched at a constant rate of elongation until it breaks. Record the breaking strength and elongation at break, and if necessary, record the breaking strength and elongation at break.
Sample: the effective width is 50mm
Gauge length: 200mm, if the elongation at break exceeds 75%, the gauge length can be 100mm
Tensile speed: 20mm/min-100mm/min. Different elongation sets different speeds.
Clamping specimens: loose clamping and pretension clamping.
Test according to "GB/T 20655 Protective Clothing - Mechanical Properties - Regulations on Piercing Resistance".
Puncture resistance: The maximum force required to make the test nail penetrate the test sample at a certain speed.
Sample: diameter not less than 50mm
Vertical stroke: not less than 100mm
Test nails: made of steel with a minimum hardness of 60HRC, the dimensions are as follows:
Put the sample and the clamp ring on the strength tester, so that the outer surface of the sample faces the test nail, and the test nail penetrates the sample at a constant speed of 100mm/min. If the test nail cannot penetrate even after reaching a height of 25 mm after contacting the sample, the test should be terminated and noted in the report.
Test each specimen in turn and record the maximum force required to penetrate the specimen.
Low temperature resistance and high temperature resistance
Cut 5 samples in each direction of warp and weft, and then treat the samples at the specified temperature for 8 hours, and then within 5 minutes according to "GB 3923.1 Tensile properties of textile fabrics Part 1: Determination of breaking strength and elongation at break ( Strip method)" stipulates that the breaking strength test is completed, and the average value of the test results is used as the final test result of the direction of the sample.
According to the formula to calculate the rate of decline in the breaking strength of the material after low-temperature or high-temperature treatment, accurate to one decimal place.
R: Decrease rate of fracture strength after low temperature or high temperature treatment;
F0: The average breaking strength of the warp or weft direction of the fabric without low temperature or high temperature treatment, the unit is cattle (N);
F1: The average breaking strength of the warp or weft direction of the fabric treated at low temperature or high temperature, in N (N).