NFPA 53 Recommended Practice on Materials, Equipment, and Systems Used in Oxygen-Enriched Atmospheres, 2004 ed. https://www.nfpa.org/assets/files/AboutTheCodes/53 /53-F2009-ROP.pdf, (Recmm Prac: on Mtrl, Equip and Sys Used in Oxy-Enriched Atm - Amer) {209 NFC}