1. The facial fit is good. The air leaked from the mask with a gap is directly inhaled from the gap without passing through the filter material, which seriously reduces the protective effect. Leaks can also cause glasses or goggles to fog. Preferably, the leakage rate is less than 1.5%.
2. The filtration efficiency of the filter material should be high. KN9, KN95 and KN1, the higher the filtration efficiency, the higher the interception rate of particulate matter and the lower the penetration rate of particulate matter. Gauze masks, common medical masks and medical surgical masks all have low requirements on particle filtration efficiency. Preferably KN95/KN1/KP1.
3. The protective effect should be high. The protective effect is the ability of the mask to block particles, which is a comprehensive embodiment of leakage and filtration efficiency. D, C, B, A, preferably Grade A, greater than 9%.
4. The inspiratory resistance should be low. The higher the inspiratory resistance, the more difficult it is to inhale, and the mask will have to be taken off after wearing for a while, which can not continue to protect. Preferably, the inspiratory resistance of KN95 mask is less than 5 Pa.
5. The expiratory resistance should be low. The greater the expiratory resistance, the more uncomfortable you feel, and you can't wear it for a long time. It is best that the expiratory resistance of KN95 mask is less than 5 Pa.
6. The air tightness of the exhalation valve is better. If there is an exhalation valve, it is better that the time for the air tightness of the exhalation valve to recover from -118 Pa to normal pressure is more than 5 seconds. The exhalation valve is not airtight enough to effectively isolate external particles, especially toxic gases.
7. The dead cavity rate should be low. Dead space rate refers to the proportion of carbon dioxide re-inhaled from the previous exhalation. The lower the ratio, the less carbon dioxide inhaled from the previous exhalation, the fresher the inhaled air and the higher the inhaled oxygen content, preferably less than .1%.
8. The headband, connector and exhalation valve cover are subject to greater tension. Wearing it will be strong and the connection will be tight, preferably more than 1 cattle.
9. In addition, the mask does not discolor, has no peculiar smell, has low formaldehyde content, neutral PH value, and has no carcinogenic dyes.
1. The mask must have a test report from a third-party professional organization. If the seller does not have a test report or does not show the test data, it is not credible.
The development technology of masks is changing with each passing day, and the protective performance index of traditional masks has fallen behind. You can look at the new mask of Mushengtang with more than a dozen patents.