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Float switch

Float switch is an automatically working electric unit, contains two parts: the float ball with switch inside) and a long waterproof power cable. It can be operated by low and high voltage as well. They are widely used in irrigation tanks to open and close filling or emptying electric valves and regulate water level in the tank. Good alternative to float balls when their positioning is difficult.

There might be other use of this equipment on an irrigation system.

Certain submersible pumps are also factory-fitted with float switch to avoid dry running.

Operation, test and maintenance


Most common use of these equipments is the filling. When the floating ball drops, a mechanical switch lifts inside the floating ball and the circuit (inside the ball) closes and the filling solenoid (installed on the water inlet of the tank) is operated, opens and let the water fills up the tank.

When the appropriate water level is reached, the ball floats up and the switch opens the circuit, hence the solenoid closes, and the water stops.

Obviously, when the float switch is used to empty a tank (with a diffefrent setting), it is connected on the other way and closes the circuit, when the level is high.

Regular testing of float switches are important. It can be performed by lifting them up. If they are fillers, the water inlet should run and stops when they are released. Obviously they should work on the opposite way in case of emptying switches.

You have to make sure that the float switch is positioned on the same level than before and can float and hung freely when you release in the tank at the end of the test.

Float switches are in an waterproof enclosure, hence no maintenance is required.


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