MMT310 Series Moisture and Temperature Transmitters for Oil

The Vaisala HUMICAP® Moisture and Temperature Transmitter Series for Oil MMT310 is a fast and reliable on-line detector for moisture in oil.

  • Continuous measurement of moisture in oil with excellent long-term stability
  • Proven Vaisala HUMICAP® sensor, over 15 years in oil applications
  • Measurements in lubrication, hydraulic and transformer oils
  • Excellent pressure and temperature tolerance
  • Measuring water activity - ppm calculation for transformer oil
  • Small size, easy to integrate
  • NIST traceable calibration (certificate included)
  • Applications: e.g. monitoring of transformer oil and of lubrication systems in marine and paper industry

MMT310 Series Moisture and Temperature Transmitters for Oil

Operating Principle

The Vaisala transmitters used for measuring moisture in oil feature the HUMICAP® sensor, a capacitive thin-film polymer sensor especially developed for demanding moisture measurements in liquid hydrocarbons. The HUMICAP sensor consists of four functional layers: glass substrate, lower electrode, water-active polymer layer, and porous upper electrode.

The thin-film polymer either absorbs or releases water as the surrounding moisture level changes. Water molecules move to/from the polymer layer until there is moisture equilibrium between the polymer and the oil.

The dielectric properties of the polymer depend on the moisture level. As the moisture level changes, the dielectric properties of the polymer film change, and so does the capacitance of the sensor.

The instrument’s electronics measure the capacitance of the sensor and convert it into water activity. Oil molecules or additives do not penetrate the electrode. Thus the sensor output is independent of the oil type.