Fixed Butyl/EPDM Diaphragm-Industry's Thickest;Factory Pre-Charge-12 PSIG;Max. Operating Temperature-240 Degree F;1-Year Warranty;For use in closed, non-potable hydronic heating and chilled water systems;Designed to meet all ASME Code Section VIII, Division 1 standards;Available with optional sight glass and seismic restraints;Suitable in propylene glycol applications with mixtures up to 50%;Deep drawn models are lighter, stronger and more compact than traditional head and shell construction