Decagon VP-4 Sensor

– temperature, humidity, VPD & barometric pressure

VPD SensorContinuously monitor temperature, relative humidity, vapour pressure deficit (VPD) and barometric, all in one sensor, with the VP-4.

The VP-4 is a digital, SDI-12 sensor that is compatible with our range of diverse data logging solutions or connect the sensor to your existing data logging system.

The VP-4 can be inserted into a radiation shield for accurate meteorological and weather measurements.


  • Low cost, high accuracy
  • IP65-rated environmental protection
  • Radiation shields with natural or forced ventilation
  • Compact, weather proof design


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feature specification
relative humidity
Measurement Range 0 to 100% RH
Measurement Accuracy Temperature and RH dependent | 2 to 5 %
Response Time (τ, 63%): < 40 s
Hysteresis < 1% RH typical
Signal Drift < 0.5% RH/year typical
Measurement Range -40 °C to 80 °C
Measurement Resolution 0.1 °C
Measurement Accuracy 0.5 °C
Response Time < 400 s
Signal Drift < 0.04 °C / year typical
vapour pressure deficit (VPD)
Measurement Resolution 0.01 kPa
Measurement Accuracy 0.07 kPa at 20 °C
barometric pressure
Measurement Range 49 to 109 kPa
Measurement Resolution 0.01 kPa
Measurement Accuracy 0.4 kPa
general specifications
Dimensions 1.96 cm (dia) x 5.4 cm (h)
Power Requirements 3.6 to 15 VDC 0.03 mA quiescent, 4 mA during 300 ms measurement
Response Time 300 ms
Output SDI-12
Operating Temperature -40 °C to 80 °C
Connector Types 3.5 mm (stereo) plug or stripped and tinned lead wires (pigtail)
Cable Length 5 m standard; custom cable length available upon request
Data Logger Compatibility Any SDI-12 enabled data logger