Discharge to the outside closed and open circuit

The exhaled breath of the former is not directly discharged to the outside, but is supplied for circulating breathing after purification and nourishment. It is safer but has a complicated structure. The exhaled breath of the latter is directly discharged to the outside. Be affected.

In addition, it can be divided according to the applicable field and occasion, and can be divided into industrial masks, fire masks, emergency escape masks and diving masks.