How Do Gems Float Switches Work

Gems float switches are devices used to detect the level of liquid within a tank. The switch may be used in a pump, an indicator, an alarm, or other devices. Float switches range from small to large and may be as simple as a mercury switch inside a hinged float or as complex as a series of optical or conductance sensors producing discrete outputs as the liquid reaches many different levels within the tank.

For Appliances
There are many different types of float switches, some of which are mercury switches that activate by allowing the liquid metal to complete the circuit, and others that are simple floats connected to a micro-switch that activates the device. They are common in sump pumps, dishwashers and other appliances.

For Pumps
A very common application is in sump pumps and condensate pumps where the switch detects the rising level of liquid in the sump or tank and energizes an electrical pump which then pumps liquid out until the level of the liquid has been substantially reduced, at which point the pump is switched off again.

Adjustable Switches
Gems float switches are often adjustable and can include substantial hysteresis. In other words, the switch’s “turn on” point may be much higher than the “shut off” point. This minimizes the on and off cycle that is associated with the pump.

For Septic Tanks
In septic systems where gravity flow is not an option, installers often use a pump system. This system includes three mercury float switches. The lowest switch is set to stop the pump. The middle switch activates the pump. Under normal circumstances, the fluid level remains between these two switches, keeping the pump submerged in effluent water to protect it from corrosive sewer gas. However, if the pump stops working, the tank fills to the point of activating the third switch.

Dual-Stage Switches
Some float switches contain a two-stage switch. As liquid rises to the trigger point of the first stage, the associated pump is activated. If the liquid continues to rise (perhaps because the pump has failed or its discharge is blocked), the second stage will be triggered. This stage may switch off the source of the liquid being pumped, trigger an alarm, or both.

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