Series FV-4 automatic vent valves are used in commercial and residential hydronic heating applications to provide automatic air venting for hot or cold water distribution systems. It consists of a brass body construction with male NPT connection, brass cover, air vent with silicone rubber seal, polyethylene float with valve plug and automatic vent. Series FV-4M1 has a high temperature rating and is ideal for use with glycol systems or for use as an anti-vacuum device. It can also be installed to permit the separation and dispersal of air while fluid is circulating in the system. Can be disassembled for inspection and cleaning.