A couple of times now I have read about limited or no use of "restricted breathing enclosures, nR type protection" for hydrogen and acetylene enviornments because of their typical breathing factor being >20 [molecule size?] . Only mention in a standard is AS 2380.9 Appendix A , for breathing factors for gasses : 1991. I can not find anything on "restricted breathing factors" and wondering if this has been withdrawn .
thanks in advance
thanks in advance