Factors Affecting Float Switch Applications

A float switch is a device that floats on the surface of liquids in a tank, rising and falling with the level of the liquid and providing an early warning if the liquid level rises above, or drops below the range of the float switch. They can be used in a wide variety of applications, from coffee machines and deep fat fryers in commercial kitchens, to sumps, pumps and industrial scale tanks. The type of switch required will be dependent on the application.

Float switches are tethered to a fixed mount via a cable. The length of this cable will be one factor to determine the selection of switch. For smaller scale applications, or where the optimum range of liquid level is minimal, a short cable is required. For large scale tanks, applications where greater range of liquid level is possible or for more turbulent conditions, a longer cable will be required. The greatest cable length is determined by weight, as it can’t be so heavy as to stop the switch from floating. All float switches come with manufacturer instructions covering the maximum cable length.

The voltage and current in the application must also be considered. Outside of the standard ranges, there are specific switches for low or high voltage and currents. If the incorrect selection is made, the float switch will malfunction. For example if a standard switch was used in a low voltage and current application, residues would gradually build up on the switch and prevent the contacts from conducting. This would leave the application at risk of flooding or drying out.

A narrow angle float switch is a suitable solution for accurate measuring, as small variations in the liquid level will activate the switch. These narrow angle switches are not suitable in pumps or liquid with currents, due to the regular movement of the liquid which would ‘accidentally’ activate the switch (e.g., false readings). At the other end of the spectrum, mechanical float switches are generally advisable as the best solution in highly turbulent applications.

There are other factors which determine the best product to use. These include the temperature of the liquid being monitored, the pressure and whether it is a corrosive substance. Float switches can be constructed from a range of materials, including nylon, stainless steel and PVC, each of which has its own properties that make it more or less reliable in these types of specific situations.

A float switch provides a valuable monitoring service, which prevents costly and time consuming issues from arising. It can be activated when the liquid level drops below a minimum level. This warning system means the liquid levels can be increased before the tank runs dry. It can also be activated when the liquid rises above a maximum level preventing overflowing and flooding. By protecting the appliance it is placed in, as well as other machinery that is connected to it and the space and contents around it, a float switch is a highly cost effective device.

For more information, go to TAV Engineering.

Source: GoArticles by Author Liam Johnson .

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(Image Credit –TAV Engineering. )

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