Wescor's L-51 and L-51A in situ leaf psychrometer.

L-51 and L-51A

The L-51 Leaf Hygrometer is designed for in situ measurement of leaf water potential, using either the wet bulb or dew point method of data readout.  L-51A has a special chamber configuration for use with grass.  The all-metal thermocouple mounting system is similar to that used in the C-52 Sample Chamber.  Given isothermal conditions, this configuration provides rapid equilibration and excellent precision

A copper-constantan temperature sensor allows accurate ambient temperature measurements to be made for correction of psychrometric readings or for Pv temperature correction when encountering large temperature changes.  In use, the section of leaf to be tested is swabbed clean, then inserted in the lateral slot in the body of the sensor.  Gentle pressure is applied to capture the leaf between the mount and the measuring chamber.  A small amount of petroleum jelly or a beeswax-lanolin mixture is used to effect a vapor seal.

A nylon mounting bracket is included with the sensor to provide thermal isolation from metal support structures.


Size:                                     19 mm x 25 mm x 46 mm (exclusive of leads)

Weight:                                 Approximately 100 grams

Lead Length:                         1.5 meters

Range:                                   -0.05 MPa to -7 MPa nominally

Slot Width:                            2 mm

Chamber Dimensions:

                             (MODEL L-51)         3 mm diameter x 2 mm deep

                             (MODEL L-51A)      3 mm by 2 mm x 2 mm deep

Used with the HR-33T or Wescor / Campbell systems.  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.)

SUREFAST™ connector option available (specify L-51-SF or L-51A-SF).