Smart Barometric Pressure, Humidity and Temperature Sensor

The Smart BHT is an integrated barometric pressure, relative humidity, and temperature sensor that meets WMO specifications. In addition to instantaneous measurements, this smart sensor can sample measurements every second and output the average, min/max levels and standard deviation of those sample over logging intervals. The Smart BHT also computes the dew point.

  • Meets WMO guidelines*
  • Digital output that autodetects SDI-12 or Modbus RTU commands.
  • 279 micron, 316T stainless steel mesh for insect and dust protection.
  • Dew point calculation.
  • One second sampling with output average of samples over logged interval.
  • Min / max of samples over log interval. y Standard deviation output of samples.
  • Lightning protection: Gas discharge tube on SDI- 12 data line, IEC-rated RS-485 transceiver with TVS diode protection.
  • Replaceable sensor board for rapid recalibration replacement.

Solar Radiation Shield

The optional solar radiation shield protects the sensor from rain and solar radiated heat. The shield consists of 6 curved UV-resistant white plastic plates with an internal funnel design that allows air flow to efficiently pass through the shield assembly, while blocking direct solar rays and radiated temperatures for surrounding surfaces. Universal mount fits 3/4” to 1-1/2” pipe for flat surfaces.

Technical Specifications

OutputSDI-12 (version 1.4) / Modbus RTU. Sensor autodetects the output signal
Current draw500 uA average, 12 mA peak for 50 ms during startup
Power supply voltage6 to 18 VDC (12 VDC typical)
WiringRed: 6 - 18 VDC; Black: GROUND; Blue: SDI-12; White: RS-485 A/+; Green: RS-485 B/-
Cable typeUPG 20 AWG 5C polyethylene underground direct burial low energy circuit
DimensionsDiameter: 0.70” (17.8 mm), Length 4.17” (106.0 mm)
Barometric PressureRelative HumidityTemperature
Range260 to 1260 hPa0 to 100%-40°C to +70°C
Sensor typePiezo-resistiveCapacitive resistiveSilicon bandgap
Accuracy0.1 hPa from 0 to +65°C±3% (0 to 80%); ±5% (80% to 100%)0.1°C from -20°C to +70°C
Resolution.01 hPa1%.01
Initial sensor response time1 s20 s10 s
Unit of measure optionshPa, mBar, Bar, PSI, TorrPercentCelsius, Fahrenheit
WMO Guidelines for reference*
Range500 - 1080 hPa0 to 100%-40°C to +50°C
Resolution0.1 hPa1%.01 K
Sensor time constant20 s40 s20 s
Output average time1 min1 min1 min
Achievable measurement uncertainty0.3 hPa3%0.2 K


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