YSI TruLine 21 - Manual (Page 6)

Commissioning, measuring, calibration TruLine
6 T 814240 04/2014
be stored. Always keep the watering cap clean.
 TruLine 25, TruLine 26 and TruLine 21: Remove any gas bubbles behind
the pH membrane by shaking. W ith all other combination electrodes, gas
bubbles behind the pH membrane are not a problem.
 Connect the combination electrode to the meter.
 Calibrate the combination electrode according to the operating manual of
the meter and observe the following rules while doing so:
Calibration
and measurement:
General rules
 Avoid the displacement of any solution (sample or buffer solution) from
one measurement to the next by taking the following measures:
– Shortly rinse the calibration and sample beakers with the solution the
beakers are to be filled with next.
– Between measurements, rinse the combination electrode with the so-
lution that follows. Alternatively, you can also rinse the combination
electrode with deionized water and then carefully dab it dry.
 To measure in aqueous solutions, it is recommended to immerse the com-
bination electrode in a vertical or slightly tilted position.
 Observe the correct depth of immersion and make sure the contact be-
tween the junction and test sample is thorough. The junction is in the area
of the bottom end of the shaft (see arrow).
TruLine 25
TruLine 26
Caution:
TruLine 21 TruLine 27
Only the shaft part of the combination electrode may be immersed!
 For measurements in aqueous solutions, provide approximately the same
stirring conditions for measuring as for calibrating.
Subsequent
calibrations
The frequency of subsequent calibrations depends on the application. Many
meters provide an option where you can enter a calibration interval. After the
calibration interval has expired, the meter will automatically remind you of the
due calibration.