US lawArizonaRegulationsTitle 11 — MinesChapter 1 — State Mine InspectorR11-1-412R11-1-412R11-1-412. Fan housings and air ductsLast amended: 1980Length: 15 wordsOfficial source Cite as Ariz. Admin. Code § R11-1-412Fan housings and air ducts connecting main fans to underground openings shall be fire resistant.PreviousR11-1-411NextR11-1-413