intercept

Dust particles in the air, with the air flow for inertial motion or random Brownian motion or movement by the role of a certain field force, when particles hit other objects, the object of van der Waals force between (is molecules and molecular, molecular mass and the force between the molecular mass) make particles adhering to the fiber surface. Enter the filter medium of dust have more chance to hit medium, hit medium will be stuck. Smaller dust will collide with each other mutual bond formation of larger particles and subsidence, concentration of dust particles in the air is relatively stable. Interior walls and the fading of for this reason.

The fiber filter like a sieve view is wrong.

Inertia and diffusion

Particles of dust in the air for inertial movement, when encounter arranged disorderly and fibre, air change direction, because of inertia swerve, and bumped on fibre by adhesive. The particle is larger, the easier the impact, the better the results.

Small particles of dust for random Brownian motion. The more severe the smaller particles, has no regulation motion, chance to hit an obstacle, the more the better filtering effect will be. In the air is less than 0.1 microns particles mainly for Brownian motion, small particles, filtering effect is good. Greater than 0.3 micron particles mainly inertia motion, the bigger the particle efficiency is higher. Diffusion and inertia are unknown is one of the most difficult to filter out particles. When measuring high efficiency filter performance, people often prescribed most difficult measurement of dust efficiency value.

Electrostatic interaction

For some reason, fiber and particle could take charge, produce electrostatic effect. With electrostatic filter material filtering effect can be improved significantly. Reason: electrostatic dust changing trajectory and hitting obstacles, electrostatic dust sticky stronger on the medium.

Long-term with electrostatic material is also called "electret materials. Materials with electrostatic resistance is changeless, after filtering effect will be improved significantly. Electrostatic not decisive role in the filtering effect, only a supplementary role.

Chemical filter

Chemical filter main selective adsorption harmful gas molecules.

Abound in invisible microporous activated carbon materials, have larger adsorption area. The size of a grain of activated carbon, the micro hole area of about a dozen square meters big.

After free molecules, activated carbon, condensed into a liquid by capillary principle in microporous stay in micro hole, some with material and as a whole. There is no obvious chemical reaction is called physical adsorption.

Some process, activated carbon adsorption of particles and the material for reaction, generate solid matter or harmless gas, known as chemical adsorption.

Activated carbon materials in the process of using the adsorption ability of weakening, when reduced to a certain extent, the filter will be scrapped. If only for physical adsorption, heat or steam smoked can make the harmful gas from activated carbon, activated carbon regeneration.

Gravity effect

Particles through fiber layer, under the action of gravity, from the displacement of air flow and sedimentation on the fiber surface, the effect only when large particles (> 0.5 um) exist, this is too small particles gravity, when it hasn't settlement on the fiber has been with the air flow through the fiber layer. Therefore, the grain size is less than 0.5 um particle filtering, gravity sedimentation can be ignored completely.