Extrol® expansion tanks accept expanded fluid in closed-loop hydronic systems to control pressure build-up, improve comfort and help reduce energy costs. Nearly seven decades after inventing the first diaphragm expansion tank, Amtrol® line-up now includes specialty models engineered for modern, high-efficiency systems. None of it would have been possible without Extrol® The One That Started It All™. Amtrol® EXTROL® Hydronic Expansion Tank, Vertical, Series: SX Series, 86 gal, 26 in Dia, 47 in Height, 100 psig, Acceptance Factor: 0.53, 46 gal Acceptance Capacity, 240 deg F, Heavy Duty Butyl/EPDM Diaphragm, Steel Shell, Urethane Topcoat, Domestic