Section 4 - Chemical Resistance
Hydrocarbons
Hydrocarbons are the unburned portion of fuels in a fire that can be carried by the heat and gases up in the air and deposited on firefighting equipment. The soot often found on helmets after a fire will contain some of these hydrocarbons. This unburned material is the primary source that can attack some of the older thermoplastics used prior to 1992. Although there is a remote chance that some fuel fires could deposit enough hydrocarbons on a recent thermoplastic helmet to create damage, it is unlikely. Manufacturers have not seen any complaints in recent years to indicate that this remains a problem.
Solvents
Certain chemical solvents can be harmful to fire helmet shells. In practice, this has not been a significant issue in terms of fireground chemical exposures in recent years; it more commonly is encountered in the cleaning of helmets. Thermoplastic materials tend to be more sensitive to chemical attack than composites, and care should be taken in selection of liquid cleaning agents. Only detergent and warm water should be used to clean fire helmet faceshields and shells, whether thermoplastic or composite. If there is any question about the performance of helmets in a particular chemical environment or the use of a cleaning solvent, the helmet manufacturer should be contacted.