Decagon VP-4 Humidity/Temp, Vapour & Barometric Pressure Sensor

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

SDI-12 Compatible

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


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 it 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.

Humidity Resolution 0.1% RH
Temperature Resolution 0.1°C
Vapour Pressure Resolution 0.01 kPa
Barometric Pressure Resolution 0.01 kPa
Humidity Range 0-100% RH
Temperature Range -40°C to 80°C
Vapour Pressure Range 0-47 kPa
Barometric Pressure Range 49 to 109 kPa
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
Power Requirements 3.6-15 VDC, 0.03 mA quiescent, 4 mA during 300 ms measurement
Sensor Dimensions 5.4 cm x 1.96 cm
Data Logger Compatibility Em50 series, ProCheck, SDI-12 capable loggers
Warranty One year, parts and labour

Non UK/Ireland Customers

Non UK/Ireland Customers, please contact Decagon Devices at:

Radiation Shield Included

The included radiation shield is designed to improve air temperature readings by minimizing radiation and maximizing 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.



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

Quotation Request

Email us to request a quotation for the Decagon VP-4 Humidity/Temp, Vapour & Barometric Pressure Sensor