Atmospheric Tank 4 : A storage tank that has been designed to operate at pressures from atmospheric through a gauge pressure of 6. 9 kPa (1. 0 psig) (i. e. , 760 mm Hg through 812 mm Hg) measured at the top of the tank
NFPA 122 Standard for Fire Prevention and Control in Metal/ Nonmetal Mining and Metal Mineral Processing Facilities, 2004 ed. http://catalog.nfpa.org/NFPA-122-Standard-for-Fire -Prevention-and-Control-in-MetalNonmetal-Mining-an d-Metal-Mineral-Processing-Facilities-Prior-Years- P4168.aspx, (Std: FrPrev and Cont in Metal/ Nonmetal Mining and Metal Mineral Procss Fcilty - Amer) {254 NFC}