Physical and Chemical Geotechnologies

Purpose

Objective is to study the available approaches to calculate pressure difference of filtering respirators, to determine theoretical dependences of its change in terms of different filtering rate according to the breathing process with the use of filtering models of interconnected channels and parallel cylinders, and to generalize the results obtained in the context of mathematical models.

Methodology

Simplified equations of Navier-Stokes in Euler form taking into consideration imaginary mass forces of Zhukovsky resistance are applied to analyze laminar movement of the air within a porous medium

Findings

For the first time, regularities of the process of airflow passing through a porous filtering material have been theoretically substantiated in terms of breathing process; that has made it possible to determine the dependence of pressure difference on respirator filters in the context of changeable filtering rate taking into account volume and frequency of human breathing as well as in terms of filter parameters, i.e. coefficient of penetration and porosity of a filtering layer. It has been determined that pressure difference on disposable half-masks while breathing depends not only upon resulting friction force when airflow passes through filtering layers, but also upon the level of inertial oscillations of air velocity around fibers which increases along with the growth in density of filtering layers and reduction in the radius of their fibers. Optimal indices of filtering layer porosity have been defined to provide minimal pressure difference in terms of Lepestok dust respirator.

Keywords: Dust Respirator, Pressure Difference, Breathing Resistance, Breathing Frequency, Air Loss, Filter Resistance, Coefficient of Penetration

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