Xylem FDO 925 - Manual (Page 8)

Measuring / Operation FDO
®
925
24 ba75898s01 04/2010
2.4 Function check and user calibration
Factory calibration The FDO
®
925 is factory calibrated. In the recommended application (see
page 22), the measuring characteristics of the sensor cap remain stable for
the specified service life. Thus, a user calibration is not usually required.
When does a func-
tion check or user
calibration make
sense?
A function check or user calibration can be useful in the following special
cases:
z If the measured values appear to be implausible and it is assumed that the
service life of the sensor cap is over
z Routinely within the framework of the company quality assurance.
Check or calibra-
tion medium
The check and user calibration take place in water vapor-saturated air. The
suitable conditions are easily provided with the aid of the check and calibra-
tion vessel, FDO
®
Check. For this purpose, moisten the sponge inside the
vessel. Then insert the sensor in the vessel as far as it will go. The sensor
membrane must be clean and dry for this.
Moisten the sponge:
z Remove the cap (1).
z Take out the sponge (2), wet it, then slightly squeeze it out.
z Insert the sponge again and close the calibration and storage vessel with
the lid.
After inserting the sensor, wait for the temperatures of the sensor and
calibration vessel to adjust.
Note
The steps of the check or user calibration are described in detail in the oper-
ating manual of the meter.
2.5 Storage
Always store the sensor in the check and storage vessel (FDO
®
Check) at a
temperature in the range 0 ... 50 °C (32 ... 122 °F).
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