CMC TMS-SS-P-20-F Portable Electrolytic Dew Point Sensor

Overview

The CMC TMS-SS-P-20-F is a portable, field-deployable electrolytic dew point sensor engineered for high-precision trace moisture measurement in industrial gas streams. Based on the well-established phosphorus pentoxide (P₂O₅) electrolytic principle, the instrument quantifies water vapor concentration by electrochemically dissociating H₂O molecules at a platinum anode and recombining them at a cathode—generating a current directly proportional to the partial pressure of water. This fundamental coulometric relationship ensures intrinsic calibration stability and long-term reproducibility without reliance on periodic span gas verification. Designed for use in compressed air, nitrogen, argon, hydrogen, natural gas, and other inert or reactive process gases, the TMS-SS-P-20-F delivers reliable dew point readings down to –70 °C DP (typical range: –70 °C to +20 °C DP), with minimal drift under continuous operation. Its compact form factor and battery-powered operation support both spot-checking and short-duration monitoring in valve pits, skid-mounted systems, and mobile laboratory environments.

Key Features

• Electrolytic P₂O₅ sensing cell with platinum electrodes deposited on borosilicate glass substrate—ensuring chemical inertness and resistance to poisoning from hydrocarbons or acidic contaminants.
• Stainless steel measurement chamber with Viton sealing rings—optimized for compatibility with aggressive gas matrices while maintaining leak-tight integrity at pressures up to 0.5 barg.
• Precision-engineered 6 mm stainless steel Swagelok®-compatible compression fittings—enabling rapid, tool-assisted connection to standard gas sampling lines without adapters or ferrule mismatch.
• Fixed flow control at 20 NL/h—maintained via integrated critical orifice, eliminating dependence on external mass flow controllers and reducing system complexity.
• Operating temperature range of +5 °C to +50 °C—validated for ambient deployment in non-climate-controlled industrial settings, including outdoor compressor stations and packaging line environments.
• ±1% full-scale accuracy—traceable to NIST-certified moisture standards and verified per ISO 8573-3:2010 Annex B protocols for electrolytic hygrometers.

Sample Compatibility & Compliance

The TMS-SS-P-20-F is validated for use with dry, non-corrosive, and low-particulate gas streams. It is not recommended for direct measurement of wet, condensing, or particulate-laden gases without upstream filtration (e.g., sintered stainless steel filter ≥5 µm) and coalescing pre-dryers. The sensor complies with IEC 61000-6-2 (immunity) and IEC 61000-6-4 (emissions) for industrial electromagnetic environments. While not intrinsically safe certified, its low-power design (<2 W nominal) supports integration into Class 1, Division 2 hazardous area systems when installed within appropriate barrier-protected enclosures. Data output adheres to Modbus RTU over RS-485, enabling seamless integration into SCADA and DCS platforms compliant with ISA-88 and ISA-95 frameworks.

Software & Data Management

The sensor operates autonomously without embedded firmware-based data logging; instead, it outputs analog (4–20 mA) and digital (Modbus RTU) signals simultaneously for redundant acquisition. When connected to CMC’s optional PC-based configuration utility (TMS-Config v3.2), users can perform zero calibration verification, adjust damping filters (0.1–10 s), and export timestamped dew point and temperature values in CSV format. All configuration changes are logged with user ID and timestamp—supporting audit readiness under GLP and GMP environments where electronic record integrity per FDA 21 CFR Part 11 is required. No cloud connectivity or proprietary cloud platform dependency is introduced.

Applications

• Verification of dryer performance in pharmaceutical compressed air systems per ISO 8573-1:2010 Class 2 or Class 3 specifications.
• In-line moisture monitoring during cryogenic air separation unit (ASU) purge gas validation.
• Field qualification of nitrogen blanketing systems prior to reactor charging in fine chemical synthesis.
• Commissioning support for semiconductor fab bulk gas delivery systems requiring <1 ppmv H₂O compliance.
• Troubleshooting moisture ingress in LNG custody transfer lines and offshore pipeline pigging operations.

FAQ

Does the TMS-SS-P-20-F require periodic recalibration with certified moisture standards?
Yes—while the P₂O₅ cell exhibits excellent zero stability, annual verification against traceable NIST-traceable dew point standards (e.g., chilled mirror or quartz crystal microbalance reference) is recommended per ISO/IEC 17025 accreditation requirements.
Can the sensor be used with hydrogen gas?
Yes—the platinum/glass/Viton construction is compatible with high-purity hydrogen (≥99.999%) at specified pressure and flow conditions; however, exposure to hydrogen containing >1 ppm CO or NH₃ may accelerate electrode aging.
Is the 6 mm fitting compatible with standard Swagelok tubing?
Yes—it accepts 6 mm OD stainless steel or PTFE-lined tubing using standard Swagelok SS-6-M2F two-ferrule compression fittings without modification.
What is the expected service life of the electrolytic cell under continuous operation?
Typical operational lifetime exceeds 24 months at 20 NL/h flow and ≤10 ppmv average moisture load; lifetime decreases inversely with cumulative water exposure (coulombs consumed), monitored via internal charge-integration counters accessible through Modbus register 40052.