Priority Demand Valves

The SEP Priority Demand Valve (PDV) – brand new for 2021 – acts to isolate the domestic/ancillary water supply in the event of a fire sprinkler activation, or in the event of a power loss.

The Requirement

BS9251 – the standard for ‘fire sprinkler systems for domestic and residential occupancies’ – states that IF:

  • the mains water supply flow rate available to the fire sprinkler system is liable to be affected by domestic water usage (e.g. shower, washing machine etc), THEN
  • a valve must be fitted to cut off supply for domestic use in the event of a sprinkler activation.

Two Products – One Solution

  • For pipe sizes from 15mm/½” up to 50mm/2” we use a quality solenoid valve with BSP threaded connections.
  • For pipe sizes from 65mm/2½” up to 150mm/6”we use an electrically actuated butterfly valve for flanged connections.

Workings and Features

  • The flow switch (water flow detector) is connected into the IP-rated enclosure, creating a circuit that maintains the valve in the open position. If the flow switch is activated then the circuit is broken which closes the valve and shuts off the domestic water supply.
  • It is strongly recommended that an approved flow switch is used with this installation, which gives added benefits of false alarm protection and two sets of contacts.
  • The unit is provided with a fitted plug for ease; however, this is easily removed, should the preference be to install directly into a fused spur.


  • Non-fail-safe valves are available by special order if there is concern about loss of domestic water supply in the event of a power loss; however, these valves will not be able to shut off the domestic supply if there is a fire sprinkler activation during such power loss.
  • Longer cables available, if required, by special order.
Priority Demand Valve

The Benefits of our Priority Demand Valves

  • All valves are WRAS-approved and therefore can be fitted directly to the mains water supply
  • 24-volt solenoid valve coil and control circuits avoid the need for dangerous 240-volt power outside the IP-rated enclosure, in a domestic environment.
  • LED indicator to confirm that power is present.
  • LED and position indicators on butterfly valve actuator.
  • Fail-safe – the valve closes if a signal is received from the sprinkler system flow switch, BUT it will also close in the event of power loss OR flow switch connection is lost, ensuring that the fire sprinkler is always safe.
  • High IP rating means more flexibility when positioning the easy-mount enclosure and the valve itself.
  • Small enclosure for Solenoid-type (just 170x80x85mm).
  • The fail-safe functionality does not preclude the installation of a (restricted/15mm/½”) bypass around the PDV (complete with lockable and/or monitored isolation valve) to allow the provision of emergency water supplies in the event of a power loss which is not caused by a fi re event.

Related Products

  • Residential valve sets (Resi Risers).
  • Approved flow switches.
  • WRAS-approved BS9251-compliant booster pump sets.

For more information about our Priority Demand Valves please call +44 161 428 1180 or email and one of our sales team will be happy to talk you through the options and quote you our latest prices.

SEP are more than happy to discuss special product requirements if you do not see what you are looking for here.

Priority Demand Valve

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