Compact, module-type Moisture and Temperature Transmitter for Oil


Compact, module-type Moisture and Temperature Transmitter for Oil


Compact, module-type Moisture and Temperature Transmitter for Oil


  • Continuous measurement of moisture in oil
  • Proven Vaisala HUMICAP® Sensor, 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
  • Applications: e.g. monitoring of transformer oil and of lubrication systems in marine and paper industry

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

Reliable Vaisala HUMICAP® Technology

The MMT310 series incorporates the latest generation of the Vaisala HUMICAP® Sensor, developed for demanding moisture measurement in liquid hydrocarbons. The sensor’s excellent chemical tolerance provides accurate and reliable measurement over the wide measurement range.

Measuring Water Activity

The MMT310 series measures moisture in oil in terms of the water activity (aw) and temperature (T). Water activity directly indicates if there is a risk of free water formation. The measurement is independent of oil type, age, and temperature.

Water Content as PPM Calculation for Transformer Oils

PPM units are traditionally used in transformer applications. They indicate the average mass concentration of water in oil. The ppm calculation for mineral oil based transformer oil is optional in the MMT310 series.

Diverse Applications and Demanding Conditions

The MMT310 series can be used in lubrication and hydraulic systems as well as in transformers. It can be used for on-line moisture monitoring and as a control function, allowing separators and oil purifiers to be started only when necessary.

Installation Options

The MMT318 has two adjustable probe lengths. The transmitter can be ordered with a ball valve set that enables the insertion and removal of the moisture probe for calibration, without the need to empty the oil system. The MMT317 has a small pressure tight probe with optional Swagelok fittings.

Several Outputs, One Connector

The MMT310 series has two analog outputs and an RS-232 serial output. The output signals and the supply power travel in the same cable, the only cable connected to the unit.

Types of Moisture in Oil Products - Fixed Installations