ABSTRACT
It must be understood that the mechanism that achieves filtration of small particles from a gas stream is not simple sieving. The spacing between fabric threads may be on the order of 50 to 75 microns, yet particles of 1 micron diameter and less are collected efficiently. Indeed, the primary collection mechanisms include impaction, interception, and diffusion, as discussed in Chapter 19. Initially, on a clean filter before any dust accumulates, the fabric threads and fibers are stationary targets for the particles. As soon as a layer of dust (dust cake) accumulates, however, the stationary particles in the dust cake become targets for the particles in the gas stream.
