Moisture Monitor – Model M70

This simple design by Envent Engineering utilizes a heated conductive polymer sensor that provides a linear output of the moisture concentration in a natural gas stream.


  • Range: 0-20lbs/mmscf (custom ranges available)
  • Rugged mechanical design
  • Affordable measurement
  • Unit will display in lbs/mmscf and/or ppm
  • 2% of reading or 10 ppm (0.5 lb per million) accuracy
  • 4-20 mA output and alarms (2-wire)
  • RS-232 and RS-485 Serial Communications
  • Ultra-low power: Less than 2 watts power consumption
  • Dual-line, 16-character display
  • Daily Auto-Zero


Power 12-24 VDC @ less than 2 watts
Enclosures ADALET XIHLGGCX 5-5/8” by 5-5/8” for Class 1, Div 1 Groups C, & D
Ambient Temperature 0-60 °C (32-140 F) Standard.
Consult factory for other requirements
Output Ranges 0-20 lbs/mmscf standard.
10-300 ppm (0.5 to 300 lbs/mmscf) optional.
Response time 20 seconds to 90% of step change wetting,
300 seconds to 90% dry down
Accuracy 2% of reading or 10 ppm (0.5 lbs/million)
Whichever is greater
Outputs • 4-20 mA.
• Serial RS 232 and 485
• Dual 3 amp solid state alarm relays.
• Modbus.
Display Dual-line, 16-character display.
Moisture in ppm or lbs/million, sensor temperature °C, Heater duty, calibration factor, and raw millivolts can be scrolled from internal button.
Auto Zero Includes ASCO solenoid and extra flow meter. Inlet sample is dried daily (configurable) for 15 minutes in a Silica Gel Moisture trap at 80 psig to provide a daily repeatable moisture concentration reference, typically 0.5 lbs/mmscf.


The unit has a 4-20 ma output and RS-232/485 serial communications, alarms, internal menu scroll buttons. The M70 can display up to 128 different parameters including lbs/mmscf, ppm, sensor temperature, raw millivolts and calibration factor and sensor heater load. The sensor is mounted in an insulated flame proof enclosure with flame arrestors installed in the sample flow path. Many natural gas tariff limits are set a 4 lbs water per million standard cubic feet. This is closely equivalent to 80 ppm or 64 mg/m3. The sensor is controlled to 50°C and operated at atmospheric pressure to maximize resistance to process variables and adsorption of stream contaminants.

Foul resistant. The M70 offers industry leading value in price while still maintaining reliability. The rugged sensor is resistant to chemical fouling such as amines and glycols and methanol and can be washed with alcohol without permanent damage.

Minimal Power Removable Sensor. The sensor can be readily removed for cleaning or replacement with standard tools in seconds. The linear output enables the user to perform a single-point calibration. The standard M70 uses less than 2 watts power when installed in areas where ambient temperature is more than 0°C. This means it can be used at sites where only solar or other minimal power is available.