ISO 11999-5:2015

ISO 11999-5:2015 specifies the minimum design and performance requirements for helmets as part of personal protective equipment (PPE) to be used by firefighters, primarily but not solely to protect against exposure to flame and high thermal loads.
NOTE   A Type 1 helmet is similar to helmets for fighting fires in structures according to EN 443:2008. A Type 2 helmet is similar to helmets used for fighting fires in structures according to NFPA 1971:2013. However, following ISO 11999-1, all parts of heat and flame resistance requirements are consistent with each other, therefore heat and flame tests consistent with requirements for clothing given in ISO 11999-3.