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Type of mask testing
The performance of dust mask shall conform to the requirements described in the right column of the following Table when tested according to the test procedures described in the left column of the same Table.
Test procedures：
The particulate filtering efficiency is measured by the measurements of the particle concentration of the test air flow before and after it passes the dust mask, and by the succeeding calculation in use of the following equation. The particle used for the test of particulate filtering efficiency is chosen either of the following two kinds depending on the kind of the particulate filter. The particle size distribution of the test particles is represented by the count median diameter.
1. The case where the test particle is sodium chloride;
The concentrations of sodium chloride in the test flow before and after passing through the dust mask are continuously measured with a sodium chloride concentration measuring instrument with the light scattering method. The count median diameter of the particle size of sodium chloride shall be from 0.06 micrometer to 0.10 micrometer and the geometrical standard deviation of the particle size distribution shall be less than 1.8. The air flow containing sodium chloride at the concentration lower than 50 mg per cubic meter with the variation range less than 15% is made pass through the respirator at the flow rate of 85 liters per minute until the cumulative sodium chloride supplied to the respirator reaches at 100mg. The particulate filtering efficiency is calculated for the maximum concentration of sodium chloride after passing the respirator during the test.
2. The case where the test particle is dioctyl phthalate;
The concentrations of dioctyl phthalate in the test flow before and after passing through the dust mask are continuously measured with a dioctyl phthalate concentration measuring instrument with the light scattering method. The count median diameter of the particle size of dioctyl phthalate shall be from 0.15 micrometer to 0.25 micrometer and the geometrical standard deviation of the particle size distribution shall be less than 1.6. The air flow containing dioctyl phthalate at the concentration lower than 100 mg per cubic meter with the variation range less than 15% is made pass through the dust mask at the flow rate of 85 liters per minute until the cumulative dioctyl phthalate supplied to the respirator reaches at 200mg. The particulate filtering efficiency is calculated for the maximum concentration of dioctyl phthalate after passing the respirartor during the test。
Test of inhalation resistance：
This test measures the difference between inner and outer pressure of the dust mask on a dummy head during passing air flow at the rate of 40 liters per minute in the direction of inhalation. (This pressure difference is hereafter called as "inhalation resistance" in this Table.)
Test of exhalation resistance：
This test measures the difference between inner and outer pressure of the dust mask mounted on exhalation resistance test equipment when an air flow is passed at the rate of 40 liters per minute into the dust mask in the direction of exhalation. (This pressure difference is hereafter called as "exhalation resistance" in this Table.)
Test of air tightness of exhalation valve at work：
First, the exhalation valve with the valve seat is mounted on an air tightness test equipment, and then the decrease of the inner pressure of the valve is confirmed by drawing the inside air by a drawing pump at the rate of 1 liter per minute. Next, the inner pressure is adjusted at -1,470 Pascal against the atmospheric pressure, and then the drawing of the inner space of the valve is stopped, and then the time for the inner pressure to recover to the atmospheric pressure is measured. The capacity of the inner space of the exhalation valve seat shall be 50 cubic centimeters.
Test of carbon dioxide concentration increase in inspired air：
In the atmosphere of 25±5°C, the facepiece is put on a dummy head with the dimensions described in the following picture, and the connected artificial breathing apparatus is driven at the rate of 15 times a minute and 2.0±0.1 liters per stroke (The artificial breathing apparatus supplies exhalation air with 5.0% carbon dioxide.). During this procedure, the carbon dioxide concentration in the inspired air is measured until the concentration reaches a constant concentration. The same procedure is performed with the dummy head without a facepiece.
2020-08-06 10:03
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