Analysis of pressure difference changes in respirator filters while dusting

Objective is to determine the relation between pressure
difference of a filter and parameters of a filtering layer to lengthen the
protection period. The study involved elements of system analysis and
mathematical modeling. Basic statements of the theory of nonstationary
filtration and aerohydrodynamics were applied to develop a dust-loaded
filter model. Dependence of pressure difference in a filter upon certain
changes in packaging density of dust-loaded fibers has been determined;
the dependence makes it possible to define minimum fiber packaging
density to provide maximum dust capacity. To provide maximum dust
capacity and high protective efficiency, the number of filtering layers in
multilayered filters depends upon dust concentration within the air of the
working zone, specified protection level of a respirator, air loss, and
maximum dust volume which may be accumulated in the finishing filtering
layer in terms of fiber packaging density being determined according to the
minimum pressure difference in a filter at final time of respirator operation.
A model of changes in pressure difference in filtering respirators in the
process of aerosol particles depositing on filters has been improved;
contrary to other available models, that one takes into consideration
changes in fiber packaging density while dusting, filtration coefficient, and
the amount of aerosol particles.