BS 8468-6.1:2020 pdf free.Respiratory protective devices for use against chemical, biological, radiological and nuclear (CBRN) agents.Positive-pressure compressed air line equipment一 Specification. BS 8468-6.1 This British Standard specifies requirements for compressed air line breathing apparatus with positive pressure demand valve for use with a full face mask as a respiratory protective device intended to be used during firefighting, rescue, evacuation, escape,...