Increasing Your Accuracy - Decagon WP4-T Operator's Manual

accurately measured by the WP4. Following is
an example:
Sample too dry
< -64.8 MPa
This message will stay on the screen until you
open the sample drawer. If you know that your
sample's water potential is below what the
screen is telling you, your instrument's sensors
may have been contaminated and will need to
be cleaned (see Chapter 10) or serviced (see
Chapter 11).

Increasing your Accuracy

Under normal operating conditions, your WP4
should be reading with an accuracy of ±0.1 MPa
from 0 to -10MPa and ±1% from -10 to -60 MPa. You
can increase the accuracy of your WP4, provided
you take certain precautions. Here are some steps
you can take to improve your instrument's accuracy
up to ±.05 MPa:
• For successful operation, the WP4 requires very
precise temperature measurement and control.
Therefore, the WP4-T model will work best for
eliminating these variables. For a standard WP4
(not temperature-controlled), it is best to make
measurements in a room with fairly constant, or
WP
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PotentiaMeter
Taking a Reading