Influence of the maintenance on protective properties of firefighters’ helmets under low-impact energy condition

Helmets are included in the group of personal protective equipment and are used when other hazard control methods are insufficient. They protect against head injuries caused by various environmental factors, e.g. mechanical and thermal loads, as well as flames. Injuries due to falling debris are serious and may be fatal. Taking that into consideration, the basic role of helmets is to absorb impact energy and dissipate it over a greater surface to decrease forces acting on the head. The following work aims to study the influence of maintenance on the energy absorption capacity of firefighters’ helmets.The research was conducted on two helmet models that differ in design, both new ones and maintained for 4 years. Shells of one group of helmets were manufactured using an injection moulding method, while shells of the second group were made as a laminate. Tests were carried out using a drop hammer with the impact energy at the level of 30 J.Maintenance had a significant influence on the energy absorption mechanism. An increase in fragility and decrease in stiffness of a shell was observed, which reduces the protective properties of helmets. It constitutes a real hazard for firefighters.The research results refer to specific helmet models. The influence of the maintenance on the protective properties of other models of helmets may be different.The research results indicate that a visual assessment of firefighters’ helmets’ technical condition is insufficient. The durability of helmets should also be determined by the time of use.The paper contains original research results. According to the author’s knowledge, the results of the influence of maintenance on the protective properties of firefighters’ helmets have not been presented in any scientific publication.