Research of the influence of filter element resistance on the powered air-purifying respirator service life

The purpose of the research was to determine the influence of the increasing resistance of filter elements on the service life of powered air-purifying respirators during operation in mining conditions and to substantiate the parameters of the respirator power source. The research was conducted by the computer-based simulation methods for the powered air-purifying respirator operation, which allows estimating the additional resistance of the filter caused by dust accumulation. The simulation model of the powered air-purifying respirator was developed on the basis of its physical model and, taking into account the empirical dependence of the change in the filter element resistance during dust deposition, allows determining the flow of air through the filter and the dust aerosol concentration in the working area air. The following parameters of the simulation model of a powered air-purifying respirator were substantiated: controlling action – fan rotating speed, restrictions on air flow and air pressure in the respirator mask (depending on the mode of working arrangements of the user), concentration of dust in the air of the working area, capacity of the power source, power consumption of the electric motor of the fan and control system components, parameters of filter elements (fibre packing density, filter layer thickness, fibre diameter, etc.), input concentration of dust aerosol, which made it possible to establish the relationship between the value of the filter element resistance and the time to complete discharge of the power source. A critical value of the resistance of the filter elements of the powered air-purifying respirator was established, which results in a significant discharge of the power source, based on the different flow rate of the air supplied to the undermask space at a given dust concentration in the working area. Relationship between the change in breathing resistance of the filters and the discharge of the power source was established, which allows determining the period of safe operation of the powered air-purifying respirator, based on the concentration of dust in the working area air and the user’s working arrangement. The practical value involves determining the lifespan of the powered air-purifying respirator, based on the critical value of the filter resistance, which results in the rapid discharge of the power source