The Conbraco Industries D-2419-00 Diaphragm is a replacement sealing component designed for Conbraco 36 Series pressure-reducing valves used in HVAC water supply and hydronic heating systems. It responds to changes in inlet pressure by flexing against the valve mechanism, regulating water flow to maintain consistent downstream pressure. This diaphragm helps prevent pressure fluctuatio... https://www.partshnc.com/d-2419-00-conbraco-industries-diaphragm-for-36-series