VP-4 HUMIDITY, BAROMETRIC PRESSURE, TEMPERATURE AND VAPOR PRESSURE SENSOR

Measurements: Relative Humidity, Temperature

Applications: Irrigation Scheduling, Plant Ecology, Water Balance Studies

Relative Humidity, Barometric Pressure, Air Temperature, and Vapor Pressure

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.

 

Compact

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

 

Weatherproof

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 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.

Figure 1: VP-4 Relative Humidity Accuracy

Figure 2: VP-4 Vapor Pressure Accuracy

Figure 3: VP-4 Temperature Accuracy

RELATIVE HUMIDITY

 

RANGE
0 to 100% RH
ACCURACY
Sensor measurement accuracy is variable across a range of temperatures. 
Refer to the chart in Figure 1 to determine the accuracy specification for the VP-4 sensor.
EQUILIBRATION TIME (Τ , 63%) 
(τ, 63%): < 40 s (response time in 1 m/s air stream)
HYSTERESIS
< 1% RH typical
LONG TERM DRIFT
< 0.5% RH/year typical

TEMPERATURE

 

RANGE
-40 °C to 80 °C
RESOLUTION
0.1 °C
ACCURACY
Sensor measurement accuracy is variable across a range of temperatures. Refer to the chart in Figure 2 to determine the accuracy specification for the VP-4 sensor
EQUILIBRATION TIME (Τ , 63%) 
< 400 s (response time in 1 m/s air stream)
LONG TERM DRIFT
< 0.04 °C / year typical

VAPOR PRESSURE

 

RANGE
0.01 kPa
RESOLUTION
Sensor measurement accuracy is variable across a range of temperatures and RH. 
Refer to the chart in Figure 3 to determine the accuracy specification for the VP-4 sensor.

BAROMETRIC PRESSURE

 

RANGE
49 to 109 kPa
RESOLUTION
0.01 kPa
ACCURACY
0.4 kPa

GENERAL

 

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 (MEASUREMENT) TIME

 300 ms

OUTPUT Decagon Digital or 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
(NOT EXCLUSIVE)
Decagon: Em50 Series (Firmware 2.19+)
Campbell Scientific: Any logger with serial I/O (CR10X, CR850, 1000, 3000, etc.)
HANDHELD READER COMPATIBILITY
ProCheck (rev 1.57+)
SOFTWARE
COMPATIBILITY
ECH2O Utility (rev 1.74)
DataTrac (rev 3.11+)
 

Splice Kit

Repair damaged cables in the field with few tools and less time.