The principle of the dry filtration process is to apply a pre-selected “filteration medium” responsible for separating the particles from the aspirated air. Good filtration efficiency also depends on good cake formation on the surface of the filter element.
The fabric of the filter bag serves as the basis for the formation of a layer of dust (cake). The surface of the filter element must allow the formation of a cake, which is responsible for much of the separation of dust particles from the air. The layer generated on the surface of the bag can also be used as a neutralizing element for dangerous chemical components in the suction air.
The new filter bags allow the passage of small particles, in the order of 0.5 µm, leading to contamination of the fiber interior. The pre-coating consists of particles between 50 and 60 µm in size, which, when filtered, form a layer on the surface of the fabric preventing its clogging.
The pre-coating is also used to prevent particles of ignition, flame, moisture and / or hydrocarbons, increasing the life of the filter element and improving the energy efficiency of the system, since it reduces the head loss associated with the filtration process.
It is recommended, due to the above, the injection of pre-coating in “new filter elements”, suggesting an approximate amount of 250g / m2 of filtering area.