Light liquid level signal

To replace the old-fashioned eye-control method of detecting the level of the liquid, appliance manufacturers now use reed sensors to show when the container for Jet-Dry needs refilling. The reed sensor is mounted underneath, or next to, the liquid container. A floater with an internal permanent magnet is placed in the container and floats on the liquid. If its level falls to a minimum, the floater activates the reed sensor which, in turn, activates a light on the front control panel of the dishwasher, signaling the need to refill the Jet-Dry container. 

Modifled from McAvoy, 1983). A decanter shown in Fig. E18.14 is used to separate a feed that consists of two completely immiscible liquids, a light component and a heavy component. Because of the large difference in their densities, the two components form separate liquid phases very rapidly after the feed enters the decanter. The decanter is always full of liquid. The level of the interface I between the two liquid phases is measured by a dp cell. Each liquid flow rate can be adjusted by using a control valve, which is connected to a standard PI controller. The control valve equations relate flow rates, pressures, and controller output signals (mi, m2, m3) ... 

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