The concept of protective masks
Protective masks including dust masks, respirators, gas masks, according to the principles of structure and function, can be divided into filtering and isolation of respiratory protective devices-two categories.
Filtering respiratory protective devices: it is powered by the wearer's own breathing, and harmful substances in the air to be filtered. Applies to hazardous substance concentration is not high in the air, and oxygen content in the air is not less than 18% sites are available in both mechanical and chemical filtration.
Isolation (gas)-respiratory protective devices: this type of respiratory protection site does not purify the air that is inhaled air, but otherwise supply. According to the gas supply can be divided into input from the outside world in two classes.