19
•
Calibration with zero oxygen standard
Normally, it is enough to calibrate the instrument in air at 100%, as explained previously. However,
sometimes it is also necessary to calibrate at 0%, for example when:
•
A probe is replaced by a new one
•
The probe is not used for a long period of time (over one month)
•
A complete maintenance of the sensor is performed
•
The instrument does not calibrate at 100%, in this case calibrate it before at 0%.
•
The instrument does not measure correctly
For calibration at 0%, proceed as follows:
Before proceeding, perform a maintenance of the probe DO 7
. (chapter 11)
Turn the instrument on, dip the probe in the water and wait for the polarization time of 10 minutes. Then,
dry the probe thoroughly with paper towel and proceed as follows:
•
Put the probe in the Zero Standard Oxygen and wait for 5 minutes.
•
In measure mode, press the button
, remain in Menu
DO SETTINGS P5.0
and confirm pressing
the button
again.
•
Press the button
again, confirm the entry into submenu
CAL 0 P5.1
.
•
On the display, the string “
POINT oxy 0.0
” appears; the device will search for the value %O
2
= 0%.
•
Gently stir the probe in the Standard and eliminate any air bubbles under the membrane, moving the
sensor.
•
The scrolling on the display of four red bands
means that the measurement is not stable yet.
•
Consider the measurement truthful only when the stability icon appears
.
•
Confirm the value by pressing the button
.
•
The instrument automatically returns to measure mode.
•
The beaker icon
appears at the bottom left, indicating that the instrument is calibrated on value
0% O
2
.
ATTENTION:
Before proceeding with the calibration operations, carefully consult the safety data sheets
of the substances involved:
•
Zero oxygen Standard calibration solution
Note
: The Zero Oxygen Standard Solution is SINGLE DOSE! After its use, contact your local distributor for
the purchase.
Perform the calibration in air at 100% too. This procedure remains saved, even after the
turning off of the device.