Study of protective efficiency of respirator with forced air supply

The aim of the work was to conduct experimental studies aimed at determining the protection factor of the filter respirator with forced air supply by volunteers in different modes of operation and to establish the dependence of the amount of air supplied by the fan from the air purification device to the filter’s resistance. Simulation studies to determine the protective effectiveness of the filter respirator on the testers were performed according to the procedure for determining the penetration coefficient of test aerosol – sodium chloride, as the ratio of the submask concentration of test aerosol to the ambient concentration formed in a special chamber that meets the requirements of DSTU EN 13274. Determination of the amount of air supplied by the air purification unit to the submask space and assessment of the value of positive pressure inside the mask was performed according to the procedure described in DSTU EN 12941: 2004. As a result of simulated laboratory tests to determine the protective effectiveness of filter respirators with forced air supply to the testers, it was found that the average result of the protection factor of the test samples ranged from 99.93 to 99.97, which meets the requirements of DSTU EN 12941: 2004. In addition, it was found that the amount of air treated by the fan of the air purification device for clean filters is 165 and 215 dm3/min for operating modes “Normal” and “Turbo”, while for the polluted filters it is reduced to 131 and 185 dm3/min, respectively. During the study, the compliance of the value of excess pressure in the submask space with the requirements of DSTU EN 12941: 2004, which should not exceed 2.5 mbar, was confirmed. It is also determined that the stability of the technical parameters of the air purification device is maintained in the specified range when charging the “Dinogy Li-Pol 11000mAh 14.8V 4S 25C” brand battery not less than 12 V to ensure the current value of not less than 1.6 A. The practical value of the results lies in determining the duration of protective action of the filter respirator, the choice of filter resistance to establish the scope and modes of operation in the developed personal respiratory protection equipment

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

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

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

Studying aerodynamic resistance of a stope involving CAD packages modeling

In the article, aerodynamic resistance of the stope face is studied in case of selective mining the coal seam. To carry out the research, the methodology of the computational experiment for evaluating the longwall face aerodynamic resistance influence on the efficiency of airing the stope face has been substantiated. The model of the stope face section, equipped with mining and backfilling mechanized complex based on the serial 1KD90 roof support has been developed in the 3D modeling software SolidWorks. The diagrams of the air stream velocity distribution, when it flows in the cross section of the longwall face working space with different positions of stoping equipment and the values of rock-cutting thickness of the seam bottom (rock ledge) have been obtained in the environment of computational module FlowSimulation. The pressure drop along the length of the aerodynamic model of the stope face section has been assessed. The dependences of the average velocity of the air stream flow on the value of rock-cutting thickness have been obtained. The obtained results can be used to improve and modernize the elements of mining and backfilling mechanized complex of machinery and equipment, as well as the technology for selective mining of thin and very thin coal seams in the Western Donbas