To ensure the safety of employees, protective helmets that have been proven as reliable personal head protective equipment against mechanical impacts are widely used. However, these have one significant flaw, which is a low electric conductivity of the material they are made from, which conditions a potential generation and accumulation of electric charges on their surface during a contact electrification «protective helmet – scalp hair».
Electric charges accumulated on the surface of a protective helmet can cause, as a result of electrostatic discharge, the ignition of many combustible substances and volatile liquids considered explosive and fire-hazardous that are used in production premises. The study addresses the problem of selecting a method to prevent electric charge accumulation resulting from contact of scalp hair with elements of protective helmets. A calculation method determines a minimum metallized (grounded) area of internal surface of a protective helmet that, in case of grounding, will ensure the flow of charges to the grounded poles. The first condition under which no electric charge generated due to the electrification of the employee's scalp hair when contacting the integral harness of the helmet can become an inflammation source, has been obtained for a specific combustible substance with minimum ignition energy and a specific ungrounded surface of a protective helmet.
The dynamics of electrostatic potential of preliminarily charged elements of the internal harness of a protective helmet in relation to the ground from the moments of their connection to a grounding device, with registration of the time of charge flow to the one-tenth of initial values, has been studied by a non-contact method, and its results have been provided. As a result, the dependence of the rate of charge flow on the area of grounded conducting coating on the internal surface of a protective helmet has been determined.
The results of the study refer to the necessity to develop a methodology for protective helmet tests during their production and to introduce amendments into their test programs.
2. Musioł M., Rydz J., Janeczek H., Kordyka A., Andrzejewski J., Sterzyński T., Jurczyk S., Cristea M., Musioł K., Kampik M., Kowalczuk M. (Bio)degradable biochar composites — Studies on degradation and electrostatic properties. Materials Science and Engineering: B. 2022. Vol. 275. DOI: 10.1016/j.mseb.2021.115515
3. Technical regulation on fire safety requirements: Federal Law of July 22 № 123-FZ. Available at: https://docs.cntd.ru/document/902111644 (accessed: February17, 2025). (In Russ.).
4. GOST 12.01.044—2018. Occupational safety standards system. Fire and explosion hazard of substances and materials. Nomenclature of indices and methods of their determination. Available at: https://docs.cntd.ru/document/1200160696 (accessed: February17, 2025). (In Russ.).
5. Jachowicz M. Electrostatic Properties of Selected Personal Protective Equipment Regarding Explosion Hazard. Journal of Sustainable Mining. 2013. Vol. 12. Iss. 1. pp. 27–33. DOI: 10.7424/jsm130106
6. Popov B.G., Verevkin V.N., Bondar V.A., Gorshko V.I. Static electricity in the chemical industry. Leningrad: «Khimiya», 1971. 208 p. (In Russ.).
7. GOST 12.1.018—93. Occupational safety standards system. Fire and explosion safety of static electricity. General requirements. Available at: https://docs.cntd.ru/document/5200318 (accessed: February17, 2025). (In Russ.).
8. Chernyy K.A., Udavikhin D.V. Assessment of Electrostatic Properties of Personal Head Protective Equipment in Explosion and Fire-Hazardous Areas. Bezopasnost truda v promyshlennosti = Occupational Safety in Industry. 2024. № 5. pp. 69–74. (In Russ.). DOI: 10.24000/0409-2961-2024-5-69-74
9. Kolokathis P.D., Zouraris D., Voyiatzis E., Sidiropoulos N.K., Tsoumanis A., Melagraki G., Tämm K., Lynch I., Afantitis A. NanoConstruct: A web application builder of ellipsoidal nanoparticles for the investigation of their crystal growth, stability, and the calculation of atomistic descriptors. Computational and Structural Biotechnology Journal. 2024. Vol. 25. pp. 81–90. DOI: 10.1016/j.csbj.2024.05.039
10. Korolchenko A.Ya., Korolchenko D.A. Explosion and fire hazard of substances and materials, and their suppressants: reference book in 2 volumes. Vol. 1. Moscow: Pozhnauka, 2004. 713 p. (In Russ.).
11. Dhinakaran V., Gokhulabalan B., Rahul Kumar A., Ravichandran M. Advancement in materials for industrial safety helmets. Materials today: proceedings. 2020. Vol. 27. Part 2. pp. 777–782. DOI: 10.1016/j.matpr.2019.12.197
12. Ilin V.A. Metallization of dielectrics. Leningrad: Mashinostroenie, 1977. 80 p. (In Russ.).
13. Lushcheykin G.A. Research methods of polymer electric properties. Moscow: Khimiya, 1988. 160 p. (In Russ.).
14. Electrostatic field meter ИПЭП-1. User manual for УШЯИ.411153.002 РЭ. Available at: https://flowmetrika.narod.ru/elektrotehnicheskoe/577-583-578-625.htm (accessed: February17, 2025). (In Russ.).
15. Nordling K., Osterman D. Reference book on physics for a scientist and engineer. Saint Petersburg: BKhV, 2011. 528 p.
16. GOST EN 397—2020. Occupational safety standards system. Personal equipment for head protection. Safety helmets. General technical requirements. Test methods. Available at: https://docs.cntd.ru/document/566418294 (accessed: February 17, 2025). (In Russ.).