This European Standard specifies, dimensions, materials and performance requirements (including methods of test) for hydraulic safety groups, of nominal sizes from DN 15 to DN 40, having working pressures 1) from 0,1 MPa (l bar) to 0,7 MPa (7 bar). Hydraulic safety groups are intended for fitting to the cold water supply of storage water heaters, having a maximum distribution temperature of 95°C, for all energy sources.
Hydraulic safety groups control and limit the pressure in hot water heaters and prevent, by one function, the backflow of warm water into the circuit, and the contamination of water in the water
heaters by the discharged water.
Hydraulic safety groups do not control the temperature but alone may ascertain the hydraulic safety of water heaters if the mechanical resistance of the water heater remains at least equal to the rating pressure.
NOTE : The use of the device specified in this Standard does not override the need to use controls (eg thermostats and cut-outs) which act directly on the power sources of water heaters.