GB/T 38413-2019Textiles - Test methods for the filtration of particulate matter (English PDF)

3.1 Particulate matter PM

2.5 Particulate matter whose aerodynamic equivalent diameter is less than or equal to 2.5 µm in ambient air.

3.2 Filtration efficiency It shall be able to generate non-oily particles and oily particles that meet the test requirements; it shall be able to neutralize the charge of the generated particles, and ensure that the particles are evenly distributed at the sampling port before filtration.

5.1.2.2 Non-oily particles Sodium chloride (NaCl) particles. The count median diameter (CMD) of the particle is 0.075 µm ± 0.020 µm; the geometric standard deviation of the particle size distribution is not greater than 1.86. The concentration of non-oily particles is set according to the product use environment. The concentration of general industrial products is not more than 200 mg/m3; the concentration of civil products is not more than 30 mg/m3. According to product needs, other test concentrations can also be set.

5.1.2.3 Oily particles Diisooctyl sebacate (DEHS), dioctyl phthalate (DOP) or other applicable oils (such as paraffin oil) particles. The count median diameter (CMD) of the particle is 0.185 µm ± 0.020 µm; the geometric standard deviation of the particle size distribution is not greater than 1.60. The concentration of oily particles is set according to the product use environment. The concentration of general industrial products is 50 mg/m3 ~ 200 mg/m3; the concentration of civil products is not more than 30 mg/m3. According to product needs, other test concentrations can also be set.

5.1.3 Test system

5.1.3.1 General requirements It shall include sample fixtures, photometers, pressure gauges and flow meters; the sampling frequency is >= 1 times/min; the detection range of filtration efficiency is 0% ~ 99.999%; the resolution is at least 0.003%.

5.1.3.2 Sample fixture It shall be made of corrosion-resistant metal materials and composed of upper and lower holders. The fixture shall ensure that the sample has a circular measured area of 100 cm2 ± 1 cm2, unless otherwise specified. There shall be no leakage at the edge of the sample after clamping; the used sealing ring shall not change the measured area of the sample. The surface of the fixture that is in contact with the test aerosol shall be clean, easy to clean, corrosion-resistant, conductive and grounded.

7.2 Temperature and humidity pretreatment

7.2.1 Equipment The sample temperature and humidity pretreatment equipment requirements are as follows:

a) The technical performance of the damp heat testing chamber shall meet the requirements of GB/T 10586;

b) The technical performance of the high temperature test chamber shall meet the requirements of GB/T 11158;

b) The technical performance of the low temperature test chamber shall meet the requirements of GB/T 10589;

7.2.2 Method Take the sample out of the original packaging and proceed as follows:

a) Place it in an environment at 38.0 °C ± 2.5 °C, where the relative humidity is (85 ± 5) %, for 24 h ± 1 h;

b) Place it in a dry environment at 70 °C ± 3 °C for 24 h ± 1 h;

c) Place it in an environment at -30 °C ± 3 °C for 24 h ± 1 h. Before proceeding to the above-mentioned

c) treatment steps, the sample temperature shall be restored to room temperature for at least 4 h before proceeding to the subsequent steps. After the step c), the sample shall be placed in an airtight container and tested within 10 h.

7.3 Washing pretreatment According to the type-A standard washing machine in GB/T 8629-2017, washing procedure 4H, use standard detergent to continuously wash the sample 3 times; after washing, hang to dry. According to product standards or negotiated by interested parties, the number of washes can also be specified separately, which needs to be stated in the test report.

7.4 Sampling requirements

7.4.1 Sampling Cut a circular sample, whose diameter is at least 150 mm, uniformly from the fabric for filtration, or a square sample whose side length is at least 150 mm.

9.1.4 When performing a non-oily aerosol test, turn on the heater, to dry the aerosol to form NaCl particles. When performing an oily aerosol test, it's unnecessary to turn on the heater.

9.1.5 After the instrument is turned on, it takes at least 30 min to make the instrument in a stable state.

9.2 Set air flow The air flow setting range shall be 0 L/min ~ 100 L/min. Under normal circumstances, the air flow of the mask is 85 L/min (if multiple filter elements are used, the flow shall be divided equally; for example, for dual filter elements, the detection air flow of each filter element shall be

42.5 L/min; if multiple filter elements are possible to be used separately, it shall be tested according to the detection conditions of a single filter element); the air flow rate of the filter fabric for the air filter is 32 L/min. The air flow rate can also be set according to product standard requirements or customer requirements, which must be given in the test report.

9.3.1 Mask

9.3.1.1 Place the sample on the sample fixture and fix it, so that the dust-facing surface of the sample faces the direction of the airflow; prevent the sample from twisting or edge gas leakage during the test.

Note 1: Test the mask as a whole without damage.

Note 2: A hot melt glue gun can be used to completely seal the breathing valve cover of the mask, so as to prevent gas leakage at the edge of the respirator valve.

9.3.1.2 Start the test button, and the gas will flow through the sample; observe and record the pre-test filtration efficiency E of the sample; the result is accurate to 0.1%. Use electronic pressure sensor or pressure gauge (5.1.3.4) to measure the pressure difference on both sides of the sample; obtain the initial resistance drop of the sample and record; the result is accurate to

0.1 Pa.

Note: It takes about 15 s to measure the pre-test filtration efficiency E and the initial pressure drop.

9.3.1.3 Calculate the estimated filter time according to Formula (1); stop the test immediately after the actual test time reaches the estimated filter time T. Use the minimum filtration efficiency that is obtained during the entire filter time T as the filtration efficiency of the sample; the result is accurate to 0.1%.

Note: Determine the final pressure drop according to product standards or negotiated by interested parties.

9.3.2.4 Test the remaining samples in sequence according to the requirements of 9.3.2.1 ~ 9.3.2.3.