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high set point and press
ENTER
and a visual display of the raw data is seen on
the LCD display. When the data is stable press
ENTER.
Press the
arrow and
number keys
to change the displayed pH to the correct value (whichever was
selected between 6.0 and 12.0) then press
ENTER,
the pH calibration
coefficients will then be automatically updated and the instrument will return to
the calibration menu.
ORP Calibration
Oxidation reduction potential is calibrated using standard solutions producing ORP of
295.2 mV and 472.2 mV.
To prepare the 295.2 mV solution, measure out enough pH 7 buffer to cover the ORP
sensor and saturate the solution with quinhydrone. This will only require a small amount
of quinhydrone and is best done by adding a pinch and then stirring for 30 seconds.
There should still be solid, undissolved quinhydrone in the solution. If no solid is seen,
add an additional amount and repeat stirring until solid quinhydrone is seen. To prepare
the 472.2 mV standard, repeat the above except use pH 4 buffer instead of pH 7.
Perform the calibration as follows:
1.
Select ORP after pressing the Calibration key, the message High or Low CAL set
point ORP mv (ENTER/ESC) will be displayed. Press
ESC
to exit without changing
the ORP calibration.
2.
If you wish to continue, immerse the probe in 295.2 mV solution, a visual display
of the raw data is seen on the LCD display. When the data is stable press
ENTER
,
the ORP calibration coefficients will then be automatically updated.
3.
Select Cal high set point and immerse the probe in solution 472.2 mV solution,
press
ENTER
a visual display of the raw data is seen on the LCD display. When
the data is stable press
ENTER
the ORP calibration coefficients will then be
automatically updated and the instrument will return to the menu.
Turbidity Calibration
The turbidity sensor is calibrated using solutions with a turbidity of 0 ntu (distilled water)
and a high value between 100 - 300 ntu's. These solutions can be prepared by diluting a
concentrated formazin solution. Beware, formazin is a suspected carcinogen. Always
wear rubber gloves when handling formazin solutions. Note: Always clean the glass tube
before calibration. To calibrate the turbidity sensor, proceed as follows:
1.
Select TURBIDITY from the calibration key, the message CAL high or low set
point TURB ntu (ENTER/ESC) will be displayed. Press
ESC
to exit without
changing the turbidity calibration.