Description: Float switches are used at larger factories and sewage plants to maintain a given level of liquid. The float switch is a round or cylindrical float with a switch attached to it. The switch keeps the circuit closed until the float reaches a certain height. Then, the mercury slides down, opening the circuit and shutting off the pump.
Amount of Mercury: Most of the switches contain other devices.
Alternative Devices: New versions of float switches are mercury free.
How to Locate The Device: Float switches are used in plants where levels of liquids such as water, oil or sewage need to be monitored. If you are at all suspicious that the plant handled large amounts of fluids, you need to look for them. Sometimes float and level switches are hidden inside storage tanks and are not always visible. When this is the case, follow electrical leads from the control unit to the switch. Float switches usually have a large hollow float. (See Picture Above)
Safe Removal: When you find the float, there will be a rod connected to it. This is a control rod that connects to the control box. Once you are at the control box, open the front and you should see a mercury filled glass ampoule. This is the only thing containing mercury in the float switch.
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