The purpose of paper is to develop an algorithm for designing the half-masks of air-purifying respirators and assessment of their safety factor of insulation. To create a 3D model of a head, two-parameter NIOSH tables (National Institute for Occupational Safety and Health) were used. The model drawings were made with the use of Solid works software package. Differential geometrical method based on applying the moving Frénet trihedral was used to design half-masks. Two designs of the respirator half-mask were developed based on the averaged length and width of face (Modification 1), and length of face and lips (Modification 2). As a result of modeling test, the area and perimeter of the mask contact line have been defined. The safety factor of half-mask insulation was calculated theoretically. It has been established that the safety factor of Modification 1 half-mask is 2.5 times higher.
Purpose. To define coefficient of protection of filtering respirators with elastomeric half-masks PR-7 in conditions of coal mines.Methods. Antidust respirators applied at mining enterprises of Ukraine were tested for determination of their protective efficiency.Findings. As a result, it was found that the protection coefficient of the provided half-masks is in the range from 5 to 34. The main reasons of half-masks protective properties deterioration are poor insulating properties of half-masks, their design defects, improper use, application of respirators in case of unacceptably high concentration of dust and also lack of standard sizes of half-masks for operating.Originality. It has been established that the value of protection coefficient in case of dust content growth due to increasing dust coarse fraction, which in combination with high moisture will quickly fill gaps on an obturation line and thereby will reduce penetration in under mask space of the half-mask. Practical implications.The received results indicate that the half-mask respirators of the PR-7 type of samples 1 and 4, used by miners, allow to provide effective protection according to DNAOP 0.00-1.04-07 "Regulations of selection and use of personal protection equipment of respiratory organs", in case of their use up to maximum allowable concentrations 12.
Purpose is development of tools for assessing the emergency hazard of facility for disposal of explosive conversion products and materials. Results have been obtained by means of the economic and mathematical modelling methods, with use of the fundamental provisions of probability theory. The main task of conversion products and materials disposal is the creation and organization of safe technological processes aimed at returning the material resources contained in the conversion products to the state’s economy after the appropriate processing, rather than at destroying these resources. As a methodological basis for assessing the emergency hazard of a facility, a provision has been accepted that an integral measure of the disposal process hazard is the economic assessment of accidents. A scheme has been constructed of successiveness of the disposal facility events and states that can lead to an accident, on the basis of which a probabilistic model of its occurrence is developed. Proposed probabilistic model of an accident initiation at the facility for disposal of explosive conversion products and materials makes it possible to predict the behaviour of facility, based on results of the equipment and service personnel state survey, as well as on the analysis of the environmental conditions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.