Dust masks are indispensable protective equipment for w […]
Dust masks are indispensable protective equipment for workers engaged in and exposed to dust. They are mainly used in working environments with low concentrations of harmful gases and vapors. Only adsorbent or sorbent is installed in the filter box. Some filter boxes are also equipped with a filter layer to prevent aerosols at the same time. Some military gas masks are mainly made of activated carbon cloth, or use water- and oil-resistant fabric as the outer layer, glass fiber filter material as the inner layer, and activated carbon-impregnated polyurethane foam as the bottom layer, which can provide temporary protection in the event of a sudden attack by poisonous gas Protection.
The role of dust masks, as the name suggests, is to prevent dust inhalation. The key to its role is the performance of the filter material, mainly:
1. The fiber fineness of the filter material
It is expressed in terms of fiber diameter and the unit is microns. Generally, the fiber diameter of the filter material used for dust masks is preferably less than 5 microns. The diameter of the commonly used polypropylene ultrafine fiber is 4.0 microns, and the fiber diameter of the perchloroethylene ultrafine fiber filter material is less than 2 microns. The drug abuse of fiber is positively correlated with the dust blocking efficiency, that is, the thinner the fiber, the higher the dust blocking efficiency.
2. The composition and structure of the filter material
The structure of the filter material is related to the manufacturing process of the filter material. At present, the molding process of synthetic fiber non-woven filter material mainly includes acupuncture method, direct injection method, bonding method, hot melt method, etc. The hot melt injection molding method is mostly used, and with this method, two or more different fiber materials can be used for composite molding, which improves the efficiency of dust resistance, is relatively soft and has good air permeability.
3. Chargeability of the filter material
The size of the filter belt classic two is positively related to the composition efficiency, that is, the greater the amount of static charge, the higher the dust resistance efficiency.
When dust passes through the filter material, the following happens:
(1) Collision retention: When the dust particle size is larger than the gap between the filter media fibers, the dust collides on the surface of the filter media, changes direction due to the reaction of inertia and force, and settles and adheres to the surface of the filter media.
(2) Hooking effect: There are burrs on the fiber. When the dust passes through the filter material, it is hooked by the burrs on the fiber to prevent particles from penetrating.
(3) Multi-layer filtration: The filter material is made of superfine fibers lapped and woven into a net, and it has a multi-layered "three-dimensional structure". When the dust passes through the filter material, it is intercepted by layers.
(4) Electrostatic effect: The filter material has an electrostatic charge, which repels the quite polar dust particles, and has an adsorption effect on the dust particles of the opposite nature, that is, captures the dust.