How Does a Float Valve Work?

You will find float valves in well systems, in bucket pumps and, of course, in toilet tanks. The concept of the float valve is simple. A floating ball or bowl moves along the surface of the water in a well or container and activates a valve or switch when the water level reaches a predetermined limit.

Flow valve against float switch

Look in the toilet and you will see a balloon full of air, connected to a bar or bar, which, in turn, is connected to a filling valve. When unloading, the float falls from the water level, the rod opens the filling valve and the water begins to flow towards the tank. The float rises to a certain extent with the water when the stem causes the valve to close and the water to stop. This is a classic example of a float valve.

The float switch operates according to the same principle, but instead of the valve, the float switch activates a switch that drives the pump. The purpose of the pump may be to fill the reservoir, as in some well systems, or to empty the well, as in a discharge pump. In the sump system, the switch is turned on to start the pump, and does not turn off when the water rises.

Ball valve control

If you want to understand the operation of the float valve, you do not need to look for the mechanism of the toilet in your bathroom. Lift the lid, pull the drain, then hold the float so that it does not fall and notice that the water remains outside. Lower it slightly and see how the water comes out, first a little, and then more and more as the ball sinks deeper into the tank. This is the opposite of what happens when the tank is full.

The float rod is connected to a spring valve, which wants to remain closed, but the force exerted by the lever, when the ball falls, opens. You can adjust the water level by adjusting the arm length and screwing or unscrewing the ball.

Some downhole systems use a float valve, such as a ball valve or a float switch, to keep the reservoir full. When the water in the tank falls below a predetermined value, the float lever introduces the pump into the well connected to the cable. The pump runs until the flow reaches the cutoff point of the pump.

What’s in the float valve?

It is easy to see the ball float and the float lever, but the float valve is hidden inside the valve body. If I could see with an X-ray view, I would see one of two mechanisms: a slide valve or a diaphragm valve.

The valve consists of a cylinder that slides horizontally. In the closed position, the chamber of the float lever presses it against the water inlet to block the water. When the float drops, the piston leaves the gate and allows the water to flow.

The diaphragm valve works similarly, except that the rubber membrane replaces the sliding cylinder. This type of valve usually has a screw that allows you to adjust the tension in the diaphragm to increase or decrease the sensitivity of the valve to the movement of the pivot arm. When tightening this screw, the ball valve diaphragm is closer to the water inlet and the valve closes earlier.