Product Overview
The Easidew PRO I.S. is an intrinsically safe dew-point transmitter designed for continuous moisture measurement in gases and non-polar liquids. It is widely used in natural gas, petrochemical, and industrial processes where reliable moisture control is critical.
- Measurement Range: –100 to +20 °C dew point
- Accuracy: ±1 °C (+20 to –60 °C), ±2 °C (–60 to –100 °C)
- Response Time: 5 mins to T95 (dry to wet)
- Repeatability: ±0.5 °C dew point
- Calibration: Traceable 13-point certificate
- Output: 4–20 mA (2-wire, user configurable)
- Output Scales: Dew point, moisture in gas (0–3000 ppmV), moisture in liquids (0–3000 ppmW)
- Supply Voltage: 12–28 V DC
- Operating Temperature: –40 to +70 °C
- Operating Pressure: Up to 45 MPa (450 barg)
- Ingress Protection: IP66 / NEMA 4
- Housing Material: 316 Stainless Steel
- Certifications: ATEX, IECEx, FM, CSA
- Process Connection: 5/8” – 18 UNF, 316 Stainless Steel
Description
Measurement Technology
The Michell Ceramic Moisture Sensor is a proprietary metal-oxide film impedance sensor developed by Michell Instruments (UK), representing the most advanced generation of capacitive/impedance dew-point sensors. Derived from early aluminium oxide sensors of the 1950s, the current ceramic design provides superior robustness, stability, and accuracy under demanding industrial conditions.
The sensor consists of a metallised ceramic structure, produced using thick- and thin-film techniques on a semiconductor-grade ceramic base. Functioning as a moisture-sensitive capacitor, water vapor permeates a conductive layer (gold-coated) into a hygroscopic dielectric beneath, causing changes in sensor impedance proportional to moisture content. These impedance changes are converted by the transmitter electronics into precise dew-point measurements, calibrated and traceable to NPL (UK) and NIST (USA) standards.
Unlike conventional aluminium oxide sensors, Michell Ceramic Sensors are resistant to zero-shift, memory effects, and drift, even under aggressive gases such as sour natural gas with high H₂S content and pressures up to 300 barg. This enables direct dew-point measurement at pipeline/process pressures, with exceptional long-term stability and reliability. In applications requiring moisture content units, combining the sensor with monitoring systems (e.g., Promet I.S.) provides accurate conversion to ppmV, mg/m³, or lb/MMSCF, with dynamic pressure compensation if needed.
Detailed Technical Specifications
Saturation Constants (for liquids): 6-point lookup table up to 3000 ppmW, programmable for 8 common liquids via software or manually
- Flow Rate: 1–5 Nl/min via standard sampling block; 0–10 m/s for direct insertion
- Overpressure Rating: 2× operating pressure (90 MPa / 900 barg)
- Electrical Connections: Screw terminal, M20 × 1.5 mm
- Diagnostic Outputs: Sensor fault = 23 mA, Under-range = 4 mA, Over-range = 20 mA
- Dimensions: L = 150 mm × Ø = 84 mm
- Weight: 1.27 kg
- Filter: Standard <80 μm sintered SS, optional <10 μm HDPE
