Water Supply Industry Interpretations and Advice

  • Area of Interest : Backflow prevention
  • Topic : Fluid category
  • Title : Safety devices that introduce water to cool systems heated by an uncontrolled heat source
  • Clause Reference : Schedule 2 paragraph 15 & G15.3
  • Reference Number : B59
  • Decision Date : June 2014

A site specific risk assessment will be needed to determine the level of risk associated with a safety arrangement that introduces water to cool a system heated by an uncontrolled heat source (e.g. solid fuel, wood and biomass) as a last resort in an emergency.

Factors that will be taken into consideration when carrying out a risk assessment will include, but not be restricted to, the location of the safety device, specifically whether it discharges into a safety heat exchanger (water jacket) or the fuel feed inlet, and the type of fuel likely to be used.

Safety devices that discharge into the safety heat exchanger (water jacket) may, following a risk assessment, be categorised as a fluid category 3 risk. However for those that discharge directly onto the fuel feed inlet, the level of risk would be dependent upon the fuel type, or types to be used, and could be as high as fluid category 5.

Where there is a discharge to drain a suitable air break to drain is required. That is to say any discharge to drain must pass through a Type AA or AB air gap or an air break to drain installed in accordance with the requirements of EN 1717.