Water Supply Industry Interpretations and Advice

  • Area of Interest : Backflow prevention
  • Topic : Fluid category
  • Title : Acceptability of two single check valves in place of a double check valve
  • Clause Reference : Schedule 2 paragraph 15(5)
  • Reference Number : B35
  • Decision Date : September 2005

Two suitably approved single check valves (Type EA device) installed in series are accepted as offering the equivalent level of protection as that afforded by a double check valve (Type EC device) providing the maximum distance between the adjacent flanges of the valves did not exceed twice their nominal bore and the operation of one component does not interfere with the operation of the other.