| Fluids levels in containers may need to be | | | | triggering an alarm. |
| monitored and controlled for a number of | | | | Float switches have uses in industry but also in |
| different reasons. It may be important to know | | | | the home. An environmentally friendly home may |
| when a receptacle is getting low on fluid or high | | | | use a rainwater toilet and the chances are that it |
| on fluid and appropriate action may then need to | | | | will be controlled by one of these devices. The |
| be taken. | | | | cistern of the toilet will need to be filled from the |
| An example of this is a submersible water pump. | | | | main rainwater reservoir. When the cistern is not |
| If it is allowed to run dry, it will quickly burn out - | | | | full enough, the switch can be set to activate a |
| therefore some sort of device is needed to | | | | pump and replenish the water supply, switching |
| prevent this happening. | | | | off again when the cistern is full, thus preventing |
| The answer is to use a float switch. Mercury tilt | | | | water overflowing and ruining the bathroom. |
| switches used to be used frequently but since | | | | In cases where the liquid being measured is |
| mercury is highly toxic they are no longer | | | | turbulent, the float switch may be triggered a lot. |
| favoured. A modern float switch is more | | | | This is known as multi-switching and may not be |
| commonly made from a reed switch, triggered by | | | | desirable as it can damage a pump with the |
| a float-mounted magnet. More complex switches | | | | repeated switching about over a short period of |
| are also available and they use a series of optical | | | | time. In these cases, the device can be set to |
| or conductance sensors. | | | | stay off for a set period of time or to activate |
| The float switch is basically used to detect the | | | | only when liquid is detected continuously for a |
| level of liquid within a container. When a | | | | programmed period of time. |
| designated minimum or maximum level is reached, | | | | Float switches are fairly simple devices but they |
| the float switch activates and triggers the desired | | | | are very useful. |
| response, such as turning a pump on or off or | | | | |