PST HF1/HF3/CRP5/HF5 Series Temperature & Humidity Transmitters
| Brand | PST |
|---|---|
| Origin | Switzerland |
| Model Range | HF1 / HF3, CRP5 Series, HF5 / HF5-EX |
| Output Options | Analog (4–20 mA / 0–10 V) and Digital (RS485 Modbus RTU, optional BACnet MS/TP) |
| Enclosure Rating | IP65 (standard), IP67 (HF5-EX variant) |
| Operating Temperature | −20 °C to +60 °C |
| Relative Humidity Range | 0–100 %RH |
| Accuracy | ±0.8 %RH (typ. at 23 °C, 30–70 %RH), ±0.15 °C (typ. at 23 °C) |
| Probe Configuration | Interchangeable or Fixed Integrated Sensing Elements |
| Certifications | CE, RoHS, ATEX II 2G Ex db IIB T4 Gb (HF5-EX), UL Listed (pending for HF5 series) |
Overview
The PST HF1, HF3, CRP5, and HF5 series temperature and humidity transmitters are engineered for high-stability, long-term environmental monitoring in mission-critical infrastructure and regulated industrial environments. These devices operate on capacitive polymer humidity sensing and precision NTC or Pt1000 temperature sensing principles—ensuring traceable metrological performance across wide dynamic ranges. Unlike single-point sensors, the PST transmitters integrate signal conditioning circuitry with temperature compensation algorithms directly within the housing, minimizing drift and enabling stable output over extended calibration intervals. Designed for continuous operation in HVAC systems, cleanrooms (ISO 14644-compliant facilities), pharmaceutical storage zones, data center hot/cold aisles, museum climate control networks, and municipal aquatic facilities, they deliver reliable analog and digital process signals compatible with DCS, PLC, and BMS platforms.
Key Features
- Modular probe architecture: Select between interchangeable plug-in probes (HF1/HF3) or factory-integrated sensing elements (CRP5, HF5) for optimized installation flexibility and maintenance efficiency.
- Multi-protocol digital communication: Standard RS485 Modbus RTU interface; optional BACnet MS/TP firmware for direct integration into building automation ecosystems without gateway dependency.
- Hazardous area capability: The HF5-EX model is certified ATEX II 2G Ex db IIB T4 Gb for use in Zone 1 gas environments—fully compliant with IEC 60079-0 and IEC 60079-1 standards.
- Robust mechanical design: IP65-rated enclosure (IP67 for HF5-EX) with UV-stabilized polycarbonate housing and stainless-steel mounting hardware suitable for indoor and semi-outdoor deployments.
- Factory calibration traceability: Each unit ships with a documented calibration certificate traceable to national metrology institutes (METAS/Swiss Federal Institute of Metrology), including as-found/as-left data at three RH points (20 %, 50 %, 80 %) and two temperature points (10 °C, 25 °C, 40 °C).
- Configurable output scaling and damping: Adjustable time constant (1–60 s) and linear/non-linear output mapping via DIP switches or configuration software to match specific control loop requirements.
Sample Compatibility & Compliance
PST transmitters support standard industrial mounting configurations—including duct mount, wall mount, and immersion probe variants—and accommodate both ambient air and low-velocity airstream measurements per ISO 7726 and ASHRAE Guideline 25P. The CRP5 series features a compact flush-mount design ideal for cleanroom ceiling grids and laminar flow hoods. All models comply with electromagnetic compatibility requirements per EN 61326-1 (industrial environment), and meet RoHS Directive 2011/65/EU material restrictions. The HF5-EX variant satisfies explosion protection mandates under EU Directive 2014/34/EU (ATEX) and carries UKCA marking for post-Brexit regulatory alignment. For life science applications, units can be validated per IQ/OQ protocols supporting FDA 21 CFR Part 11-compliant electronic records when paired with PST’s optional configuration software and audit trail module.
Software & Data Management
Configuration and diagnostics are performed using PST’s Windows-based PC tool, Transmitter Config Studio v3.2, which supports firmware updates, sensor offset adjustment, alarm threshold setting, and real-time signal monitoring. The software generates calibration reports in PDF and CSV formats, embeds digital signatures, and logs all parameter changes with timestamps and user IDs—enabling full GLP/GMP audit readiness. When integrated into enterprise SCADA or cloud-based IoT platforms via Modbus TCP gateways, the transmitters feed structured JSON telemetry payloads containing timestamped RH%, °C, dew point, and sensor health status—facilitating predictive maintenance analytics and trend-based environmental deviation alerts.
Applications
- Pharmaceutical cold chain monitoring: Continuous validation of warehouse and stability chamber conditions per ICH Q5C and EU GDP Annex 9 requirements.
- Data center thermal management: Real-time hotspot detection and cooling optimization in ASHRAE TC 90.4-defined thermal envelopes.
- Museum and archive preservation: Microclimate control for hygroscopic artifacts requiring sustained RH stability within ±2 %RH tolerance bands.
- Swimming pool HVAC commissioning: Correlation of air/water vapor pressure differentials to prevent condensation-induced structural corrosion.
- Federal and municipal infrastructure: Integration into smart city BMS deployments meeting U.S. GSA PBS-P100 and ISO 50001 energy management criteria.
FAQ
What is the recommended recalibration interval for PST HF5 series transmitters in GxP-regulated environments?
Annual calibration is advised per ISO/IEC 17025 and internal quality system requirements; however, interval extension to 24 months may be justified through risk-based assessment and historical stability data trending.
Can the HF3 transmitter be configured for dual-output (4–20 mA + RS485) simultaneously?
Yes—the HF3 supports concurrent analog and digital outputs without signal degradation, enabling parallel connection to PLC analog inputs and supervisory SCADA systems.
Is firmware update capability available in-field without returning the unit to service?
All PST transmitters support over-the-air (OTA) firmware updates via RS485 using Transmitter Config Studio, eliminating downtime during version upgrades or security patch deployment.
Does the CRP5 series meet cleanroom particle generation limits per ISO 14644-1 Class 5?
Yes—its sealed, low-outgassing housing and absence of moving parts ensure compliance with airborne molecular contamination (AMC) thresholds for ISO Class 5 and tighter classifications when installed per ISO 14644-3 Annex B guidelines.
Are custom probe lengths or materials available for corrosive or high-temperature duct applications?
PST offers OEM customization including Hastelloy C-276 probe sheaths, extended-length variants up to 2 m, and high-temp versions rated to +120 °C (consult factory for lead time and qualification documentation).
