Except for the Japanese standard (0.06-0.1 μ m), the particle size of 0.3 μ m is used as the test standard. The flow rate of EU standard is 95L / min, and that of us standard is 85L / min. In China, the suspended particle size for national standard is more than 90% of less than 5 μ m, more than 70% of less than 2 μ m, and the flow rate is 42.5l/min. The idea of "the worst case" is adopted in the inspection and certification of filter materials, that is, the worst conditions are set up when the laboratory tests are carried out. For example, the calculated diameter of ammoniated sodium salt or DOP oil mist dust particle size of 0.3 μ m in efficiency test represents the size of extremely small particles that are most easily penetrated into the filter material, and represents the breathing volume when engaging in strong physical labor. Before the test, the filter material shall be pretreated with high temperature and high humidity, which represents the harsh working environment. All these aims are to test Under such harsh conditions, if the filter material can reach the corresponding efficiency level through detection, then it will be more effective in practical application to protect the health of workers. Generally, the anti- filter material uses activated carbon or chemically treated activated carbon as the material to filter the toxic gas or vapor through adsorption or chemical reaction without being inhaled.
Degree of cohesion
The side leakage prevention design of respirator is to prevent air from passing through the gap between respirator and human face without being inhaled through filtration. Air, like water, flows first where there is little resistance. When the shape of the mask is not close to the face, the dangerous substances in the air will leak into the respiratory tract from the non close place. Well, even if you choose the best filter. It can't protect your health. According to many foreign regulations and standards, workers should regularly test the tightness of masks. The purpose is to ensure that workers choose appropriate size masks and wear them according to the correct procedures.
Filter material of respirator
For a good filter material of the protective mask, the following three conditions should be met: first, the filter efficiency is high when the mask and the user's face are well closed; second, the respiratory resistance is small; third, the user feels comfortable. There are many kinds of filter materials for dustproof masks, including ordinary fabrics, animal hair, non-woven fabrics, etc. A kind of activated carbon felt material is very popular in the national standard.
The mask must be the right size and wear in the right way for it to work. Masks on the market are generally divided into rectangular and cup-shaped. The rectangular mask must have at least three layers of paper structure to have a protective effect. The user should press the wire on the nose bridge of the mask, and then spread the whole mask along the nose bridge, so as to play the role. Let the child wear a rectangular surgical mask, because it has no fixed shape, if well tied, it can close to the child's face. Cup masks should be made sure that the density is enough after the mask is attached to the face, so that the exhaled air will not leak out. When wearing the cup-shaped mask, you can try to blow with your hands covered by the mask to check whether there is air leakage from the edge of the mask. If the mask is not tightly covered, you need to readjust the position before wearing it.
Cleaning and maintenance
The outer layer of the mask often accumulates a lot of dust, bacteria and other pollutants in the outside air, while the inner layer blocks the exhaled bacteria and saliva. Therefore, the two sides cannot be used alternately, otherwise, the dirt on the outer layer will be inhaled into the human body when it directly clings to the face, and become the source of infection. When the mask is not worn, it shall be folded and put into a clean envelope, and the side close to the nose and mouth shall be folded inward. Never put it into the pocket or hang it on the neck.
If the mask is wetted by the exhaled heat or saliva, its function of blocking bacteria will be greatly reduced. Therefore, it is better to prepare several masks at ordinary times, so as to replace them. They should be changed and washed once a day. Wash with boiling water for 5 minutes.