Inches of Mercury 1 : A unit of pressure, one of which is equal to the pressure exerted by a column of mercury 1 in. high at a standard temperature ((2)02 inches of mercury equal 1 psi or 6. 894 kilopascals)
Ralph W. Burklin & Robert G. Purington, Fire Terms: A Guide to Their Meaning and Use, National Protection Association, Boston, MA 1980 USA. (Guide: Meaning and Use, Nat Prot Association Fr Srvc - Amer) {457}