Description A.Y. McDonald Universal Mounting BracketDuraMACTM Expansion Tanks are designed for the specific purpose of accommodating the natural expansion of water in a Hydronic Heating System. To eliminate the water logging that is troublesome but normal in a plain steel expansion tank, the air and water within the tank is permanently separated by a butyl diaphragm. The in-line series shown on this page are light in weight, easy to install, and afford many years of trouble-free service.Technical Details Drawn Steel Construction Butyl Diaphragm In-line Installation Maximum Working Pressure 100 PSI Maximum Temperature 240 12 PSI Air Charge (field adjustable) Not for use with Potable Water Heating Systems DatasheetsPressure Tanks GuideHydronic Expansion Tan