A high-speed portable dew-point hygrometer, offering rapid spot-check measurements of dew point or moisture content in many applications, including compressed air, natural gas and high voltage switchgear quench gas. This lightweight, ATEX, IECEx, FM, CSA, GOST and INMETRO certified product allows more measurements per working hour than any other comparable product. A hard-wearing but ergonomic case and an easy-to-use interface allows comfortable operation in the toughest industrial environments.

Product Features

  • Repeatedly fast measurements at low pressure in less than 15 minutes for T95 down to -60°C dew point (-76°F dew point)
  • Higher pressure measurements possible – up to 35 MPa (350 barg / 5076 psig)
  • Long battery life: up to 48 hours of typical use between charges
  • Intuitive application kits allow quick and straightforward connection to your sample point
  • Durable, yet easy to handle and operate: designed for use in industrial environments
  • 4-20mA external device input for transmitter calibration and validation
  • Lightweight: less than 1.5kg (3.31 lbs)
  • 13 point traceable calibration certificate

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Technical Specification

MDM300 Intrinsically Safe
Measurement Technology Michell ceramic sensor
Accuracy ±1°C from -60 to +20°C (±1.8°F from -76 to +68°F) dew point
±2°C from -100 to -60°C (±3.6°F from -148 to -76°F) dew point
±0.2°C temperature (0.36°F)
Calibrated Range Spot Checks: -70 to +20°C (-94 to +68°F) dew point
Online Analysis: -100 to -70°C (-148 to -94°F) dew point
Uncalibrated Readings From +20 to +30°C (+68 to +86°F) dew point
Measurement Units °C, °F, K dew point & gas temperature ppmV,
ppmW for air, N2, H2, CO2, SF6
%RH, g/m3, g/kg
Option: active pressure (bara/g, psig, MPa, KPa)
°C, °F, K dew point & gas temperature
ppmw & g/kg for air, N2, H2, CO2, SF6
ppmv, lb/MMscf & g/m3 for natural gas
ppmv, g/m3 & %RH
Resolution (Display) 0.1 for all dew-point derived units and autoranging where appropriate
Resolution (Measurement) Better than 0.1°C (0.18°F) dew point
Typical Response Speed T95 in ≤15 minutes to -60°C (-76°F) dew point T95 in ≤30 minutes to -60°C (-76°F) dew point
Measurement System Repeatability Better than 0.1°C (0.18°F) dew point
Measurement System Hysteresis ±0.05°C (0.09°F) dew point
Electrical Input/Output
Auxiliary Inputs 4-20 mA loop-powered external input selectable as either dew point, temperature or pressure Connection to Michell Easidew TX I.S. or Easidew PRO I.S. via Remote Sensor Interface
Battery Type NiMH 4.8V
Battery Operating Life Up to 48 hours of typical usage between charges Up to 24 hours of typical usage between charges
Battery Charger Intelligent charger (supplied) Intelligent charger (not certified for hazardous area use)
Operating Conditions
Operating Pressure 35 MPa (350 barg / 5076 psig) max (Please consult your Michell Sales Engineer for advice on operating at pressure exceeding 15 MPa (150 barg / 2175 psig)
Operating Environment Outdoors 0 to +100% RH condensing
Operating Temperature -20 to +50°C (-4 to +122°F)
Storage/Transport Temperature -40 to +70°C (-40 to +158°F)
Mechanical Specification
Display Blue LCD graphical display
Enclosure Type Steel fiber-loaded high-impact polyamide 6
IP/NEMA Rating IP66/NEMA 4
Gas Connections 1/8” NPT female (other options available)
Flow Across Sensor 0.2 to 1.2 Nl/min (0.42 to 2.54 scfh) 0.2 to 0.5 Nl/min (0.42 to 1.05 scfh)
Gas Wetted Materials AISI 316L stainless steel AISI 316L stainless steel, PTFE Seal, Borosilicate glass, ceramic
Outline Dimensions 218 x 170 x 90mm (8.6 x 6.7 x 3.5") (d x w x h)
Weight 1.35kg (2.98lbs) 1.5kg (3.31lbs)
Data Logging 8 megabytes; Log interval: 5 to 60 sec; Logs per log file: Up to 10,000
Communications (Wireless) BluetoothTM range up to 5m (16.4’) (version 2.0)
User Interface Languages English, French, German, Italian, Portuguese, Spanish
Certification Codes

CE ATEX & IECEx – EX Group II Cat 1G Ex ia IIC T4 Ga -20°C to 60°C
CSA/FM – NEC 500 Class1 Div 1 Groups A,B,C,D T4
INMETRO: Ex ia IIC T4 Ga (-20°C to +50°C)

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