Yokogawa SC72 Personal Handheld Conductivity Meter - Manual (Page 48)

IM 12D03D02-01E
5-5
5. Handling of the SC72 Personal Conductivity Meter
* Before calibrating the meter with standard solution, check that the electrode is clean. If
stains are found, clean the electrode first. Also check that the cover (of general-purpose
sensor) and outer electrode (of sensor for high purity water measurement) are secure.
Cell constant is affected by stains or loose cover.
When calibrating, ensure that measuring range is set so that you can enter conductivity to
as many digits as possible. For example, in the table above, the conductivity of standard
solution C at 25
؇C is 1408.8. If the meter is set to autorange, or to a manual range of 0
to 2.000 mS/cm, you could set this as 1.409 (four digits). However if the range were set
to 0 to 200.0 mS/cm, you could only enter conductivity value as 1.4 (only two digits
accuracy, which is inadequate for calibration with standard solution.
Before calibrating the meter with standard solution
Check and set the following items before calibrating the meter with standard solution.
(1) Check sensor for stains
Check that there are no stains on the sensor. Also check that the meter cover (for
general-purpose sensor) or outer electrode (for sensor for high purity water sensor) are
not loose.
(2) Setting temperature coefficients
When the meter is calibrated with a NaCl solution, set a temperature coefficient
(indicated by “NaCl”) for NaCl solution. When it is calibrated with a KCl standard
solution, set a temperature coefficient of 0.00 (%/
؇C).
(3) Standard solution temperature
For a NaCl standard solution, check that the standard solution temperature is in the range
25
؇C ؎ 10؇C.
For a KCl standard solution, stabilize its temperature at 25
؇C ؎ 1؇C or 18؇C ؎ 1؇C.
If it is difficult to maintain the above temperatures, set the temperature coefficient of KCl
standard solution in the meter. To find the temperature coefficient, refer to table 5.2
above and to Section 7.3, “Temperature Compensation and Finding Temperature
Compensation Coefficient.”