Capacitive switches for opening or closing electrical contacts at a preset liquid level thresholds.
A capacitive liquid level switch is an instrument for monitoring the height of a liquid and tripping a relay contact switch or transmitting solid state relay switch output when a maximum, minimum or intermediate level has been reached. The liquid level switch output can then be utilised by other instrumentation to open a valve, illuminate a warning lamp, activate an audible alarm, or switch on a pump.
Featured liquid level measurement products
18.605 G Low Cost Submersible Diesel Fuel and Water Tank Level Sensor - Low cost OEM diesel fuel or water level sensor for installing inside or outside a storage tank. 
Water Level Transmitters with 4-20mA Output - Browse for 4-20mA water level transmitters using two-wire loop power. Ideal for wells, tanks, rivers & reservoirs with excellent noise immunity & long cable runs.
Capacitive liquid level switches are threshold contact trip devices which typically consist of a single probe which acts as an immersed electrode inside a tank. This probe interacts with an opposite electrode, usually the the wall of the tank or an outer tube, and the two are connected together to form a capacitor.
The liquid contents of the tank act as the dielectric medium, which will affect the capacitance created between the two electrodes. If the liquid level rises and falls, this will change the capacitance measured by the probe in a predictable way, and therefore it can be used very effectively as a measurement of liquid level.
Featured liquid level measurement products
Tank level transmitter monitoring accessible globally via smartphone - Industrial solution for connecting your existing 4-20mA level transmitters to the internet. Enable global monitoring on your smartphone with live data, trends, and SMS alarms.
LMK331 Screw-In Ceramic Level Transmitter - Level pressure sensor with semi-flush ceramic diaphragm and stainless steel or PVDF wetted parts in ranges from 0-4 to 600mH2O gauge.
A capacitive liquid level switch probe makes direct contact with the liquid to be measured, and therefore material compatibility has to be a consideration, but for most applications a stainless construction is more than adequate for most fluids.
Since the capacitive level switch probe is essentially a stainless steel rod fitted to a tank, it is possible to construct the device to withstand high pressures so that it can be used on sealed pressurised tanks.
Also, since there is no sensitive components immersed in the fluid it is possible to use them on higher temperature media that would not be tolerated by other types of liquid level switch.
Capacitive liquid level sensing probes are generally mounted through the top or side of a tank with probe protruding into the tank. Probes mounted into the side of the tank will activate when the fluid reaches the probe. Probes that extend down the tank can be set to trigger at different levels using multiple contact switch relays.
Featured liquid level measurement products
Storm surge protected low range submersible river level transmitter - This submersible level transmitter offers accurate low range water level monitoring with high overpressure resistance for storm surge protection in rivers- LMK382 Low Range IP68 Waste Water Level Transmitter - Submersible Low Range waste water level transmitter with intrinsically safe option for monitoring the level of sewage and effluent in water treatment plants.
Advantages
- Works well on dielectric fluids
- Simple mechanical construction
- No moving parts requiring regular inspection and maintenance, or leading to wear and tear
- High temperature fluid compatibility since no sensitive components make contact with the fluid
- Sealed pressurised or evacuated vessels will not affect performance
Disadvantages
- Doesn’t work with conductive fluids without insulated outer tube
- Thick or sticky media will leave a coating on the probe creating an insulation layer causing malfunction, or affect performance
- Requires calibration to distinguish difference between liquid and air.
- Sensitive to changes in media which cause dielectric constant to change
- Probe protruding into liquid causing obstruction, attracting fouling and hygienic cleanliness issues
Featured liquid level measurement products
IWSL Potable Water Submersible Level Sensor - IP68 protect pressure sensor for monitoring potable water level to depths of 100 metres.
Harbour seawater level sensor with digital display & relay outputs for tidal applications - Seawater compatible marine bronze level sensor with digital display and relay outputs for for tidal monitoring and controlling pumps and valves in harbour environments.
Related Help Guides
- Determining the hydrostatic pressure range for a tank level sensor
- Measuring liquid level in a sealed tank with a hydrostatic pressure sensor
- Difference between vented and non-vented water level measurement
- Determining water tank volume using hydrostatic pressure
- Measuring the volume of liquid in a horizontal cylinder tank
- Measuring liquid level in a tank using a dp sensor
- How do you measure the volume of a liquid using pressure
- Liquid Level Measurement
- How to determine milk tank level and volume from pressure
- Selecting the correct pressure sensor range for low-level applications
- Installing a submersible level sensor horizontally
- Measuring diesel level in shallow tanks
- Atmospheric pressure compensation for hydrostatic level sensors
- Determining the signal cable length of a suspended liquid level transducer
- Calculating required pressure range for fuel tank level measurement
- How does changes in Local Gravity affect Hydrostatic Pressure
- Using absolute pressure sensors to measure hydrostatic level
- Using a screw-in or waterproof pressure transmitter to measure liquid level
- Improve the electrical termination of vented submersible pressure sensors
- Considerations for monitoring Landfill Water Level
- Why are Submersible applications so demanding of Pressure Transducers?
- Are all IP68 Water Resistant Protection Ratings the same
- Converting non-vented depth readings & barometric pressure to true depth
Related Technical Terms
- Capacitive Fluid Level Measurement
- cmH2O – Centimetres of Water Column at 4 deg C Pressure Unit
- Conductive Fluid Level Detection
- Float Fluid Level Detection
- ftH2O – Feet of Water Column at 4 deg C Pressure Unit
- mH2O – Metres of Water Gauge at 4 deg C Pressure Unit
- mmH2O – Millimetres of Water Column at 4 deg C Pressure Unit
- Specific Gravity
- Vibrating Tuning Fork Fluid Level Detection
Related Online Tools
- Liquid Level to Hydrostatic Pressure Calculator
- Fluid Depth, Density, Gravity, and Pressure Calculator
- Liquid Level Transmitter 4-20mA Current Output Calculator
- Vertical Cylindrical Shaped Tank Contents Calculator
- Horizontal Cylindrical Shaped Tank Contents Calculator
- Rectangular Shaped Tank Contents Calculator
- Pressure to Liquid Level Calculator
Related Product and Application Guides
Related Application Questions and Answers
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Contact us about this Capacitive Liquid Level Switches page to request more information, or to discuss your application requirements.