Rotronic HC2A-S3 Hygrometer Probe

Overview

The Rotronic HC2A-S3 is a high-precision, meteorology-optimized hygrometer probe engineered for long-term stability and traceable metrological performance in demanding environmental monitoring applications. Built upon the AirChip3000 digital microchip platform, it integrates a Hygromer HT-1 capacitive humidity sensor and a 1/3 DIN Class PT100 temperature sensor—both individually calibrated and thermally coupled to ensure minimal thermal lag and cross-sensitivity. Unlike analog-only predecessors, the HC2A-S3 delivers synchronized digital acquisition of relative humidity (RH), temperature, and derived dew/frost point with sub-second latency via UART, while maintaining dual independent 0–1 VDC analog outputs. Its extended temperature range (−50 to +100 °C) and robust polycarbonate housing—paired with a hydrophobic 40 µm polyethylene filter—make it suitable for outdoor meteorological stations, cleanroom HVAC validation, and cold-chain monitoring where condensation resistance and wind resilience (up to 20 m/s) are critical.

Key Features

• Traceable factory calibration per Swiss national metrology standards (METAS-equivalent): one temperature point (23 °C) with three RH points (10, 35, 80 %RH), documented in an individual certificate with reference instrument IDs and raw measurement data.
• Configurable dual analog outputs: each 0–1 VDC channel independently assignable to temperature, RH, or dew point—enabling simultaneous transmission of two primary parameters without external signal conditioning.
• Field-replaceable sensing element (HC2A-S3-1 module): wetted capacitive sensor can be swapped in under 10 seconds without recalibration, minimizing downtime during maintenance or contamination events.
• High-accuracy mode support: optional 9-point RH calibration (10–90 %RH at 23 °C) enables ±0.5 %RH uncertainty in controlled lab environments, meeting stringent requirements for pharmaceutical stability chambers and GLP-compliant climate testing.
• ROTRONIC HW4 software integration: provides full probe configuration (output scaling, alarm thresholds, sampling rate), real-time data visualization, audit-trail-enabled calibration logging, and automated report generation compliant with FDA 21 CFR Part 11 and GAMP 5 Annex 11.
• Low-power operation (4.5 mA @ 3.3 VDC) and flexible cabling: passive cable runs up to 5 m; active RS-485 extension supports distances up to 100 m—ideal for distributed sensor networks in large-scale weather observatories or industrial facilities.

Sample Compatibility & Compliance

The HC2A-S3 is designed for direct immersion in ambient air streams without protective enclosures in most non-corrosive environments. Its polyethylene filter resists particulate loading while permitting rapid moisture equilibration, and the polycarbonate body withstands UV exposure and thermal cycling typical of unsheltered meteorological installations. The probe complies with ISO 9001 manufacturing controls and undergoes 100% functional testing prior to dispatch. Calibration certificates conform to ISO/IEC 17025 requirements for accredited laboratories, ensuring full traceability to SI units through national metrology institutes. For regulated industries—including pharmaceutical manufacturing (EU GMP Annex 15), food safety (ISO 22000), and medical device storage (FDA Guidance on Temperature-Controlled Storage)—the probe’s audit trail, electronic signature, and calibration history management in HW4 satisfy 21 CFR Part 11 and GAMP 5 data integrity criteria.

Software & Data Management

ROTRONIC HW4 serves as the unified firmware and data platform for the HC2A-S3. It supports both local PC connection (via USB-to-UART adapter) and networked deployment via compatible Rotronic transmitters (e.g., MP100, HygroLog NT). All configuration changes—including output scaling (e.g., 0–1 V = −40 to +60 °C), alarm hysteresis, and sensor offset correction—are digitally signed and timestamped. Raw measurements are stored with metadata (probe ID, firmware version, calibration expiry), and export formats include CSV, PDF reports, and XML for LIMS integration. The software enforces role-based access control and maintains immutable logs of all user actions—critical for FDA inspections and internal quality audits.

Applications

• Meteorological observation networks requiring NIST-traceable RH data across wide temperature excursions (e.g., polar research stations, alpine weather stations).
• HVAC system commissioning and continuous monitoring in hospitals, data centers, and museums where dew point control prevents condensation on sensitive equipment or artifacts.
• Pharmaceutical stability testing chambers (ICH Q1, USP ) and warehouse environmental qualification (EU GDP Annex 9), where long-term RH drift <1 %RH/year ensures compliance over multi-year studies.
• Food processing environments subject to frequent washdown cycles—its sealed construction and chemical-resistant filter maintain accuracy despite high-humidity, high-particulate conditions.
• Academic atmospheric science labs performing eddy covariance flux measurements, where fast t₆₃ response (<15 s) minimizes phase lag in turbulent humidity signals.

FAQ

Is the HC2A-S3 compatible with third-party DAQ systems?
Yes—its UART interface follows standard TTL-level serial protocol (9600 baud, 8N1), and analog outputs comply with generic 0–1 VDC input specifications used by most industrial data loggers (e.g., Campbell Scientific, Keysight, NI DAQmx).

Can the probe be recalibrated in-house?
No—recalibration requires Rotronic-certified equipment and environmental chambers. However, users may perform field verification using portable reference hygrometers (e.g., Rotronic HygroPalm HP23-AW) and adjust offsets via HW4 if within specified tolerance limits.

What is the warranty and service lifecycle?
Rotronic provides a 24-month limited warranty. With annual verification and proper filter maintenance, typical operational life exceeds 5 years; the Hygromer HT-1 sensor module has a documented mean time between failures (MTBF) of >100,000 hours under continuous operation.

Does the probe meet IP rating requirements for outdoor use?
While not formally IP-rated, its sealed polycarbonate housing and integrated filter provide equivalent protection to IP54 against dust ingress and water splashing—validated per IEC 60529 test protocols during design qualification.

How is traceability maintained across calibration intervals?
Each probe carries a unique serial number linked to its original calibration certificate. HW4 stores all subsequent verification records, and Rotronic’s calibration service issues new certificates with updated uncertainty budgets and reference to prior calibration data—ensuring continuity for ISO 17025 audits.