Part Number: DB256
The DB pipe Interrupter is a backflow prevention device for specific Fluid Category 4 applications. The DB device features an atmospheric vent and moving element.
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 backsiphonage 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.
For Fluid Category 4 backsiphonage protection for external taps use model DBIL (pictured above). This comes complete with Interlock hose connector.
Every Hose Union Tap shall be fitted with a DB Pipe Interrupter, suitable for fluid category 4 backsiphonage protection – model DB20IL221 - as distributed by Arrow Valves Ltd – Tel 01442 823123 www.arrowvalves.co.uk. The device shall be fitted vertically and at least 300 mm above the spillover level. No valves must be fitted downstream of the device. The body of the valve shall be chrome plated brass with DN20 female inlet and DN20 male outlet fitted with a quick release hose connector2.
Amend as required
 DB20IL15 (DN20 female inlet, 15 mm male outlet with hose connector)
 DB15M256 (DN15 male inlet and outlet)
 DB20M256 (DN20 male inlet and outlet)
 DB20FM256 (DN20 female inlet and DN20 male outlet)
 Specify the desired pipe connections
The only application identified in the Water Regulations Guide is for porous hose (“leaky”) irrigation in a house garden. Water companies may accept small non-house leaky hose applications but this must be notified and consent granted.
• Hose Union Taps