Chemical Protective Clothing Testing

Chemical protective suit inspection mainly conducts scientific testing and analysis on overall air tightness testing, fabric permeation resistance testing, fabric resistance to chemical degradation testing, seam strength testing, visor optical performance and chemical resistance testing, and accessory chemical resistance and functionality testing, objectively assessing the product quality grade and issuing a detailed test report, providing a basis for manufacturers' quality control and downstream users' product acceptance.

Testing Items

Overall air tightness testing: Tests the overall sealing performance of the chemical protective suit under the positive pressure or negative pressure conditions. Usually, the inflated chemical protective suit is placed in a test chamber, and the drop value of the internal pressure within the specified time is monitored, to evaluate the barrier ability of the garment against the gases or aerosols. It is the core item for evaluating the protection effectiveness.

Fabric permeation resistance testing: Evaluates the barrier ability of the chemical protective suit fabric against the specific chemical liquids or vapours. By exposing the fabric sample to the standard test chemicals, observing and recording the time of the liquid permeation or vapour breakthrough, the protection grade and effective protection time against the different chemical hazards are determined.

Fabric resistance to chemical degradation testing: Detects the changes in the physical and mechanical properties of the chemical protective suit fabric after contacting the chemicals. After the fabric is immersed or exposed to the chemicals, the retention rates of its tensile strength, tearing strength and bursting strength are tested, to judge whether the material is embrittled, swollen or strength-reduced due to the chemical action.

Seam strength testing: Evaluates the mechanical firmness of the seams of the chemical protective suit. The tensile strength and burst pressure resistance testing are mainly carried out, ensuring that the sewn, bonded or welded seams will not crack during the high-intensity operations or accidental hooking, maintaining the overall integrity of the garment.

Visor optical performance and chemical resistance testing: Checks the light transmittance, haze and impact resistance of the mask or visor. At the same time, it needs to be tested whether the cracking, deformation or light transmittance decline occurs after contacting the chemicals, ensuring that the user maintains the detection field of vision and facial protection in the chemical environment.

Accessory chemical resistance and functionality testing: The accessories such as the zippers, valves, adjustment straps and communication interfaces are tested. Including the chemical corrosion resistance testing, repeated opening and closing life testing of the zippers, and the opening and closing function testing of the gas-tight valves, ensuring that all the accessories can work reliably for a long time in the chemically polluted environment.

Testing Scope

Gas-tight chemical protective suits: Mainly testing their overall air tightness, internal positive pressure maintenance ability and the sealing of all the interfaces (such as the connection parts of the gloves, boots and masks). This type of garments provides the highest level of protection, and the testing scope covers the comprehensive barrier performance from the fabric to the whole equipment.

Non-gas-tight chemical protective suits: The testing focus is on the liquid permeation resistance of the fabric and the liquid splash resistance of the seams. The testing scope usually does not include the overall air tightness, but adds the evaluation of the liquid barrier ability of the local sealing structures such as the liquid-tight seams and zipper flaps.

Limited-use chemical protective suits: For the protective suits designed for the single or several uses, the testing scope focuses on the initial performance before the first use, such as the permeation resistance time and seam strength. At the same time, the performance attenuation after use or contamination needs to be evaluated.

Reusable chemical protective suits: In addition to the initial performance testing, the testing scope must include the performance evaluation after the simulated use, such as the permeation resistance after multiple decontaminations, the fabric strength retention rate and the durability of the accessories, to determine their effective service life and maintenance cycles.

Chemical protective suits of the different protection grades: In accordance with the standards such as the national standard GB 24539 or the European standard EN 943, the testing scope is adjusted according to the protection grades (such as Level A, B, C, D or Type 1-6). For example, the highest-grade protective suits need to undergo the comprehensive air tightness and permeation resistance testing, while the lower grades may only test the splash resistance performance.

Chemical protective suits for the specific chemicals: The testing scope is customized according to the categories of the chemicals it claims to protect against (such as the acids, alkalis, organic solvents and toxic gases), using the corresponding standard test chemicals for the permeation resistance and degradation resistance testing.

Testing Methods

Overall air tightness testing method (pressure decay method): A stable air pressure (positive pressure or negative pressure) is injected into the chemical protective suit worn on a mannequin model or inflated, and the pressure change value within the specified time (usually 3-10 minutes) is monitored through the high-precision pressure sensors. If the pressure decay rate is lower than the standard limit, the air tightness is judged as qualified.

Liquid permeation resistance testing method (permeation cell method): In accordance with the standards EN 369 or ASTM F739. The fabric sample is clamped in the test cell, with one side contacting the challenge chemicals and the other side as the collecting medium (air or gas). Through the instruments (such as the gas chromatography) or visual observation, the time required for the chemicals to permeate through the fabric, i.e., the "breakthrough time", is determined.

Liquid splash resistance testing method (jet test): In accordance with the standard EN 463. A specific device is used to jet the liquid chemical reagents of a certain pressure, flow rate and angle onto the specific parts of the chemical protective suit fabric or the finished garment (such as the front chest and arms), evaluating whether the liquid permeates, to simulate the chemical liquid splashing scenarios that may occur in the actual operations.

Mechanical property testing method: A universal material testing machine is used. In accordance with the standards (such as ISO 13934-1 and ISO 4674), the tensile strength, elongation at break, tearing strength and bursting strength of the chemical protective suit fabric and seams are tested. The testing is usually carried out respectively before and after the chemical exposure, to compare the performance changes.

Weathering aging testing method: Simulates the long-term outdoor storage or use environment. The samples are placed in a xenon lamp aging test chamber or UV aging chamber for the aging of the specified cycles of light, heat and humidity. After the aging, the key protection performances are retested, evaluating the influence of the environmental factors on the protection life.

Finished product simulated use testing method: The test personnel are allowed to wear the chemical protective suit in the simulated environment to perform the standard actions (such as the bending, squatting, ladder climbing and arm stretching), evaluating the flexibility, comfort and the performance of the parts such as the seams, visors and valves under the actual dynamic stresses.

Testing Standards

Domestic Standards:

1. GB 24539-2021, Protective clothing — General technical requirements for chemical protective clothing

2. GB 18401-2010, National general safety technical code for textile products

International Standards:

1. EN 943, Protective clothing against dangerous solid, liquid and gaseous chemicals, including liquid and solid aerosols — Part 1: Performance requirements for Type 1 (gas-tight) chemical protective suits

2. EN 369, Protective clothing — Protection against liquid chemicals — Test method: Resistance of materials to penetration by liquids

3. EN 463, Protective clothing — Protection against liquid chemicals — Test method: Resistance of protective clothing materials to penetration by liquids (jet test)

4. ASTM F739, Standard test method for permeation of liquids and gases through protective clothing materials under conditions of continuous contact

5. ISO 13934-1, Textiles — Tensile properties of fabrics — Part 1: Determination of maximum force and elongation at maximum force using the strip method

Note: The applicable standard can be selected according to the product use and customer trade requirements; standards agreed in the contract take precedence over general standards.

Testing Instruments and Equipment

Chemical protective suit air tightness tester: This equipment includes a test chamber, pressure generation and control system, high-precision differential pressure sensor and data acquisition system. It can simulate the positive pressure and negative pressure conditions, automatically calculate the pressure decay rate, and judge whether the overall air tightness of the tested chemical protective suit meets the requirements.

Permeation resistance tester (permeation cell): The core component is a diffusion cell, usually composed of two chambers, which can clamp the fabric sample in the middle. It is equipped with a constant temperature system to control the test temperature, and connected to a gas chromatograph or other detectors, used to automatically and continuously monitor and record the permeation amount of the chemical reagents.

Universal material testing machine: Used to execute the mechanical property tests such as the tensile, tearing and bursting. The equipment is equipped with high-precision force sensors and displacement sensors, and the corresponding fixtures (such as the strip fixtures, trapezoid tearing fixtures and ball bursting fixtures) can be replaced according to the different standards, and the stress-strain curve is automatically generated.

Liquid splash testing device: Usually including a liquid storage tank, pressure pump, standard nozzle, sample fixing frame and backing material. It can precisely control the jet pressure, flow rate, distance and angle, simulate the chemical splashing scenarios, and is used to evaluate the protection ability of the chemical protective suit against the liquid jetting.

Environmental aging test chambers: Mainly including the xenon lamp aging test chamber and UV aging test chamber. They can simulate the climate conditions such as the sunlight, rain and condensation, and through the program control of the light intensity, blackboard temperature, chamber humidity and spray cycles, are used for the accelerated testing of the weatherability of the chemical protective suit materials.

Optical performance tester: Including the light transmittance and haze tester and falling ball impact tester. The light transmittance and haze tester is used to measure the light transmittance and haze values of the visor material before and after the exposure to the chemicals; the falling ball impact tester is used to evaluate the impact resistance of the visor material, ensuring its safety during use.