The proven transducer in soil research programs, Wescor's in situ soil psychrometers, model PST-55 are buried within the bulk soil to determine the soil water potential. The PST-55 has a stainless steel screen to allow only the water vapor to enter the sensor. A ceramic screen is also available as model PCT-55. To maintain temperature equilibrium, the sensors must be buried at least 15 cm under the soil surface.

The soil psychrometer must be connected to a Wescor water potential instrument such as the PSYPRO, HR-33T, or CR7 for operation.


  • Protected with Corro-Guard™  The Corro-Guard process protects the psychrometric thermocouple from corrosion even in hostile soil environments.
  • Controlled junction size and chamber geometry for consistent performance
  • Gold plated internal connections to resist corrosion
  • High sensitivity
  • Tested individually for cooling coefficient(P
  • v), leaks, cleanliness, and sensitivity
  • Individual psychrometric calibration curve provided with each unit
  • SUREFAST™ connector option available
  • When used with the  PS-10, requires the SUREFAST connector.  The HR-33T and Wescor / Campbell systems can be used with or without the SUREFAST connector


  • Psychrometer Output:         Typically 4.7 microvolts/MPa at 25° C.
  • Hygrometer Output:            Typically 7.5 microvolts/MPa at 25° C.


Specify type PCT-55 (ceramic shield) or type PST-55 (ultrafine dutch weave stainless steel screen) and 1.5 or 3 meter lead length by dash number

Example:       PCT-55-15 (1.5 meters)*          STANDARD LENGTHS

                     PCT-55-30 (3.0 meters)*

* Specify non-standard lengths in decimeters.  Example:  PST-55-100 (10 meters)

Specify SUREFAST connector option by adding SF.  Example:  PCT-55-15-SF