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Enabling better global research outcomes in soil, plant & environmental monitoring.

Decagon VP-4 Temp & Humidity

Relative Humidity, Barometric Pressure, Air Temperature, and Vapour Pressure with or without a passive radiation shield.

Use the rugged VP-4 sensor with soil moisture probes in microclimate and evapotranspiration studies.

Humidity Resolution 0.1% RH
Temperature Resolution 0.1°C
Humidity Range 0-100% RH
Temperature Range -40°C to 80°C
Sensor Type Digital Capacitance and Thermistor
Output RS232, SDI-12
Operating Environment -40°C to 80°C
Cable Length 5 m
Cable Connector Types 3.5 mm “stereo” plug or three-wire
3.6-15 VDC, 0.03 mA quiescent, 4 mA during 300 ms measurement
Sensor Dimensions 5.4 cm x 1.96 cm
RADIATION SHIELD DIMENSIONS 8.9 cm height, 10.16 cm diameter, 13.34 cm wide (bracket)
Data Logger Compatibility (Not exclusive) Decagon Em50 series (firmware 2.11 or newer), ProCheck C (Rev 1.5), Campbell Scientific
Warranty One year, parts and labour

SDI-12 Compatible

Integrate into non-Decagon data loggers with the easy-to-use SDI-12 communication protocol.


This 5 cm x 2 cm sensor is able to fit into the smallest of spaces.


Thanks to its unique Teflon screen, the relative humidity sensor can survive a deluge. Naturally, it won’t be transmitting accurately while waterlogged; but as soon as it has dried out, it’s back in the game.

Fast Response

The Teflon screen protects the sensor from liquid water and dust without limiting diffusion of water vapor. The protected sensor is still able to quickly respond to changes in humidity.

Integrated Temperature for Accuracy

Accurate relative humidity readings require accurate air temperature readings taken at the same place and time. This sensor takes both measurements simultaneously for the best possible accuracy.

Radiation Shield Included

The included radiation shield is designed to improve air temperature readings by minimising radiation and maximising airflow over the surface of the sensor. Specially designed to preserve the correlation between actual air temperature and sensor air temperature while keeping the shield size small.