This method is to be used for testing and estimating the resistance against overflow of sanitary taps designed for mixing cold and hot water. The method concerns only the overflow from one water supply system to another (hot to cold water supply system or vice versa).
Experience from water supply systems in buildings shows an increasing number of cases of overflow from one system to another. The reason lies often in the tap, because the flowresistance through the outlet of the tap is too high compared to the flowresistance through the valves of the tap.
The intention of this method is to emulate practical working situationsfor the purpose of realistic testing.
The principle for estimation is based on measurements on several makes of mixing taps. It should be possible to construct a mixing tap without any overflow at all, and therefore the limits stated in section 6.5 should be revised.