Calibration And Verification; Verification; Verification Standards - Decagon Devices WP4C Operator's Manual

Dewpoint potentiameter

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PotentiaMeter

5. Calibration and Verification

WP4C uses the chilled mirror dewpoint technique for mea-

suring water potential. This is a primary method but cleanli-

ness of the instrument can affect the calibration. The

calibration slope is fixed during factory calibration. The user

just adjusts the zero offset. Calibration can be done with

any solution of known water potential. We recommend

using the 0.5 molal KCl verification standard from Decagon.

Verification standards are specially prepared salt solutions

that have a specific molality and water potential. The

potassium chloride (KCl) verification standards are accu-

rate, easy to use, and readily available from Decagon

Devices. Most importantly, they greatly reduce prepara-

tion errors. We therefore recommend using Decagon's

KCl Performance Verification Standard for the most accu-

rate verification of your WP4C's performance.

The standards are produced under a strict quality assur-

ance regime and are shelf stable for one year. If for some

reason you cannot obtain Decagon's verification standards

and need to make a salt solution for verification, refer to

Appendix A.

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