WP4C 4 THE MENUS
Figure 4: Main Menu with Continuous Mode Enabled
Precise mode ensures a precise water potential value by repeating
measurements on a sample. Typical read times are within 10 to 15
minutes. The green LED blinks until you turn the drawer know to
the OPEN/LOAD position.
Continuous Mode
Continuous mode measures the water potential of your sample con-
tinuously until you turn the drawer knob to the OPEN/LOAD po-
sition. This can be useful in doing long term monitoring of samples
that take an especially long time to come to vapor equilibrium, such
as plant samples and moist soil samples with water potential > −0.5
MPa. In this mode the WP4C will measure the sample, stop to dis-
play the water potential and sample temperature, then begin another
read cycle. Between samples, it will signal you with the green LED
flash, accompanied by the beeper, if enabled. Some find it helpful
to connect their WP4C to a computer while in continuous mode in
order to log and store data over time. For instructions on how to do
this, see Chapter 8.
Fast Mode
In fast mode, the sample is measured only once. Read time is typ-
ically 3 to 5 minutes. Readings are less precise, particularly in the
wet range. However, fast mode is recommended for dry soil samples
with water potential < −40 MPa.
13
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