Moisture Transmitter – DewPro® MMR31

The DewPro MMR31 loop-powered moisture transmitter represents a simple, cost-effective solution for mid-range moisture measurements. The DewPro MMR31 uses a proven polymer capacitive sensor to provide a measurement range of 0 to 100% RH with an accuracy of ±2% in the range of 0 to 90% and ±3% in the range of 90 to 100%. A patented second isolated loop for temperature measurement is also available. The optional integrated display with user interface provides full programming and diagnostic capability. In addition, the unit is available with FM approval for hazardous area use.

The DewPro MMR31 provides a wide range of process humidity measurements, including relative humidity, dew point temperature, absolute humidity, and mixing ratio. These key parameters will help monitor and control critical processes. Whether you need to improve product economy, increase product quality, maintain comfort levels, or preserve the properties of stored foods or other supplies, the DewPro MMR31 allows application flexibility.


  • Loop-powered, 4 to 20 mA transmitter
  • Proven polymer capacitive sensor for fast response and calibration stability
  • Trouble-free indoor or outdoor mounting
  • Simple field recalibration with salt bottles
  • Microcontroller electronics in Type 4X/IP67 enclosure
Temperature accuracy  : ±0.9°F (±0.5°C)
Absolute humidity range  : 1 to 350 g/m3
Power supply  : 24 VDC nominal, 12 to 30VDC range
Dew point range  : 5°F to 185°F (-15°C to 85°C)


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