Mercury Displacement Industries, Inc. (MDI, Inc.) Twin Float Switch

The Twin Float pump switch consists of two floats, each float contains a mercury switch. One of the two floats contain a heavy-duty relay, which enables the floats to function in series. The relay eliminates pump chatter in turbulent conditions. The unit is well suited for narrow and deep sump pump pits. On the N.O. (pump down) model, the pump is turned on when activated by the top float switch. The pump stays on until the bottom float switch turns it off, this allows a pumping range of about 48" with the standard 54" cord length on the bottom float. This can be extended almost indefinitely with longer cords.