RH-Combo-Duct-Platinum-RTD

Supported Applications

The ACI Relative Humidity Duct with Platinum RTD Sensor series is a relative humidity transmitter designed for commercial heating and cooling building management systems. The unit features a thermoset polymer capacitive sensing element with a factory-fitted hydrophobic filter, providing resistance in applications where dust, dirt, oils, and common environmental chemicals are present.

Operating Conditions & Performance

The series measures relative humidity from 0 to 100% RH. Accuracy is specified as +/- 1% over a 20% RH range between 20 to 90%, or +/- 2% and +/- 3% from 10 to 95%. The operating temperature range for the process is -40 to 140 °F (-40 to 60 °C), with an ambient storage capability of -40 to 149 °F (-40 to 65 °C). Stability is rated at less than 2% drift over 5 years, and the typical response time (T63) is 20 seconds. The transmitter requires a stabilization time of 30 minutes before accuracy verification.

Configuration Options

The series supports multiple enclosure configurations, sensor elements, output signals, and calibration options to accommodate specific installation requirements.

• Housings: Euro style (-EH) with ABS Plastic (UL94-V0), NEMA 4X (-4X) with Polystyrene Plastic (UL94-V2), or Aluminum Plenum Rated (-BB, NEMA 3R).
• Sensing Tube Materials: -EH enclosures utilize 304 Series Stainless Steel; -4X and -BB enclosures use Schedule 40 PVC (White) with slotted PVC without filter.
• Platinum RTD Options: Available as RHx-100-xW (100 Ohms nominal @ 32°F/0°C) or RHx-1K-xW-D (1000 Ohms nominal). Configurations include Two Wires (2W) and Three Wires (3W).
• Output Signals: Factory default is 4 to 20 mA. Field-selectable options via on-board DIP switches allow for 0-5 VDC or 0-10 VDC.
• Power Supply: Supports AC or DC sources depending on output and load: 4-20 mA (250 Ω Load) requires 15 - 40 VDC / 18 - 28 VAC; 0-5 VDC requires 12 - 40 VDC / 18 - 28 VAC.
• Calibration: Units include on-board DIP switches for field calibration (increment/decrement) and test points at 0%, 50%, and 100%. Three-point NIST Calibration Certificates are available as an option.

Key Product Differences

Variants differ primarily by enclosure type, sensor resistance value, wire count, and accuracy class. The -EH (Euro) configuration features a gasketed cover with 304 Series Stainless Steel sensing tubes and sintered filters for increased moisture resistance in high humidity environments. The -4X (NEMA 4X/IP66) and -BB (Aluminum/NEMA 3R) configurations utilize Schedule 40 PVC sensing tubes without a filter.

Accuracy classes are selectable as RH1 (+/- 1% over specified range), RH2 (+/- 2%), or RH3 (+/- 3%). Platinum RTD tolerance is Class A with +/- 0.06%, adhering to DIN EN 60751 (IEC 751) standards, and includes a temperature coefficient of 3850 ppm/°C.