When it comes to liquid level sensors, instruments can be sorted into two basic classifications: point level sensors and continuous level sensors. While each classification has its similarities with the other they are useful for different applications, and many technologies will not be appropriate for both. If you need a liquid level sensor for an industrial or other application but aren’t sure if you need a continuous or point-level sensor, keep reading.
What are Point Level Sensors?
Point level sensors are devices that detect variation in liquid levels based on the presence or absence of liquid media at various points in a vessel or tank. Most often, the function of point level sensors is high level or low-level alarms, spill-prevention sensors, pump protection alarms, or pump control components.
In the simplest terms, point level sensors operate in either an on or off state and are used to control external devices that share an on/off functionality.
Examples of liquid level sensors that can work as point-level sensors:
- Horizontal Float Switches
- Vertical Float Switches
- Ultrasonic Liquid Level Sensors
- Optical Liquid Level Sensors
What are Continuous Level Sensors?
Continuous level sensors relay the exact level of a tank or vessel at any point, over a full span of measurement. This is most often used for process control or any application when absolute precision and accuracy are of crucial importance.
Examples of liquid level sensors that can work as continuous level sensors:
What Are Other Considerations for Float Switch Selection?
While knowing whether to choose a point level or continuous sensor is highly important, there are other considerations to take into account:
- Chemical Compatibility – Steel, plastic, rubber, and other materials should be selected
based on the media being measured (water, acid, fuel, et cetera). You must also take into account whether the liquid media will build up or coat surfaces; in these cases sensors with non-moving parts are preferable. - Temperature and Pressure – Depending on the operating temperature and pressure in the working environment, different materials and designs of float switches may or may not be appropriate.
- Level Measurement Range – How deep the vessel is and the required distance between the liquid surface and the sensor will help determine the right sensor.
- Tank Size and Shape – Extremely wide or narrow tanks, and those without access to mount sensors on the sides, top, or bottom, will have specific needs. For instance, ultrasonic sensors aren’t appropriate for very narrow vessels.
- Turbulence, Foam, Vapor – If the liquid media is agitated, turbulent, or produces foam or vapor, specific sensors will be necessary.
- Required Output – Different sensors are better suited for producing different outputs: analog, relay, digital, and others.
Whatever your liquid level sensing needs are, SMD Fluid Controls can help. An industry leader in float switches, liquid level sensors, and more, SMD Fluid Controls creates custom and off-the-rack solutions to everyone from huge manufacturers to at-home hobbyists. Simply tell a member of their team your application requirements, and they can direct you to the right switch. If they don’t have it, they can design one for you.