Measuring transition points in liquids with different ... - Sensortechnics

Measuring transition points in liquids with different densities withCLC and CLW capacitive level sensors1 INTRODUCTIONFirst Sensors capacitive CLC and CLWsensors allow for contact-free measurement ofliquid level and can be easily mounted to theoutside of a container or vessel. The CLCseries measures continuously whereas theCLW devices detect point levels.Further more, due to their sensitivity andteaching possibilities these sensors can beused to determine transition points between anytwo liquids with different densities and asufficient difference in relative permittivity (ε r).A typical application is the detection of wateraccumulating at the bottom of an oil tank toprevent contamination of oil systems.This application note provides instructions onhow to teach the CLC and CLW sensors toachieve optimum results.Fig. 1:Example of continuous oil over waterdetection with capacitive CLC sensorFor more information please contactFirst Sensor:www.sensortechnics.com/contactFSM@first-sensor.comE / 11160 / A1/3www.first-sensor.comwww.sensortechnics.com

Measuring transition points in liquids with different densities withCLC and CLW capacitive level sensors2 OIL OVER WATER DETECTION2.1 Continuous detection of the water levelin an oil tankOilWaterCLCsensorTeachablemeasurementrange (100 mm)Teach-in procedure1. Attach the CLC sensor to the tank so thatthe tip of the sensor pad reaches thebottom of the container (see teachablemeasurement range in Fig. 2).2. Fill the container with the liquid which hasthe lower ε r(in this application the oil) sothat at least the complete sensor pad iscovered.3. Teach the CLC sensor to LOW level4. Fill the container with the liquid which hasthe higher ε r(in this application the water)to the desired maximum level. For bestresults the complete sensor pad (100 mm)should be covered.5. Teach the CLC sensor to HIGH levelContainer wallFig. 2:Setup of continuous oil over water detectionFig. 3:Level visualisation for continuous oil overwater detection (here approx. 50 mm ofwater from bottom of the tank). For levelvisualisation an RS232 adapter may be usedto convert the 1-wire signal given by theCLC sensor.E / 11160 / A2/3www.first-sensor.comwww.sensortechnics.com