COMBITEC is used for 3-component solutions to measure simultaneously densities, sound velocities and concentrations e. g. in a mixture of acid and salt in water or in systems such as sulfuric acid/oleum or methanol/formaldehyde.


COMBITEC combines the functionality of both RHOTEC (density measurement) and SONATEC (sound velocity measurement). The instrument is designed for applications requiring maximum sensitivity and highest accuracy. It is easy to operate and maintenance-free. For density measurement the liquid flows through a thin U-shaped tube inside the sensor. Using electromagnets, the tube is excited to oscillate at the resonant frequency. At the same time, an integrated reference oscillator measures the oscillation characteristics. Even the smallest changes in fluid density have an impact on the detected signal and are identified with highest precision. For sound velocity measurement a sound pulse is created by a piezo-element in a sonic transmitter. It moves perpendicular to the product flow towards a sonic receiver where it is detected. Since the distance between transmitter and receiver is known, the sound velocity can easily be calculated by measuring the travel time of the sonic signal. As a specific property of each liquid, the correlation between concentration and density resp. sound velocity can be described by a mathematical polynomial. With decades of experience and our own laboratory facilities, Centec know the polynomials for a large number of products. Any temperature drifts of the measured signal are automatically compensated for by an internal Pt1000 sensor. COMBITEC can display liquid density, sound velocity and solution concentration in various units.

European patent application: 1 439 438 B1

  • Most accurate technology to determine density, sound velocity and concentration
  • Patented compact design with local display available
  • Large variety of materials and flange connections
  • Hygienic execution and full CIP capability
  • Easy to operate and maintenance-free

Technical Data

Measuring Range Density & Sound Velocity 0 -3 g/cm3 and 400 - 3.000 m/s
Accuracy Density & Sound Velocity ± 0,0001 g/cm3 and ± 0,05 m/s
Repeatability Density & Sound Velocity ± 0,0001 g/cm3 and ± 0,01 m/s
Response Time ≤ 1 s
Pressure of Operation max. 16 bar
Temperature of Operation - 25 - + 125 °C
Temperature Sensor Pt1000
Material 1.4404/1.4435/AISI 316L; Hastelloy; Tantalum; others on request
Connections compatible to Varivent© inline-housings DN40 - DN150; others on request
Input Transmitter Version 10 x digital (24 VDC) & 2 x analog (4 - 20 mA)
Output Transmitter Version 5 x digital (24 VDC) & 4 x analog (4 - 20 mA)
Profibus DP Transmitter Versionoption
Profibus DP Sensor (w/o local display) standard
Enclosure Rating IP65
Power Supply 24 VDC


Tel.: +49 6181 18 78 0
Fax: +49 6181 18 78 50


COMBITEC - Datasheet / Datenblatt
(0,77 MB, PDF, EN/DE)