ÖNORM EN 1491

This European Standard specifies, dimensions, materials and performance requirements (including methods of test) for expansion valves, of nominal sizes from DN 15 to DN 40, having working pressures1) from 0,1 MPa (l bar) to 1,0 MPa (10 bar). Expansion valves 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. Expansion valves do not control the temperature and alone does not constitute the protection required for storage water heaters. Expansion valves limit pressure, in the water heaters to what they are fitted, that is produced by thermal expansion of the water. NOTE : The use of the device specified in this Standard does not override the need to use controls (e.g. thermostats and cut-outs) which act directly on the power sources of water heaters.