DN20 Pipe Interrupter DB CAT4 F Inlet - M

The type DB Pipe Interrupter is a backflow prevention device for specific Fluid Category 4 applications. The DB device is often fitted to a Hose Union Tap to improve the level of backflow protection. The principle is similar to traditional bicycle tyre valves, where the flow enters a tube with the far end blanked off. This tube has several small radial holes, over which a flexible tube is stretched. The forward flow lifts the flexible tube and pushes it against the outer vent holes. When the supply pressure is released, the flexible tube contracts venting the downstream and covering the inlet holes. The DB Pipe Interrupter is approved for back siphonage protection – not back pressure. DB Pipe Interrupters are generally used externally and must not be used for washing machines or any appliance that has a control valve or restriction. They are resistant to frost damage.