Düker, whose ironworks history in Laufach and Karlstadt reaches back to 1469, manufactures the hydrants and shut-off valves that make up municipal and site firefighting water supplies. Its above-ground hydrants are built to EN 14384 and DVGW test specification W 386-P and are DVGW-certified, and its underground hydrants to EN 14339 and DVGW W 386 with DVGW type examination; Baumusterprüfzertifikate are published for the full valve range. Production is DVGW- and FGR-monitored, with plants certified to ISO 9001, 14001, 45001 and 50001 and an MPA NRW certificate of conformity.