6
OPERATIONAL PROCEDURES
A. Preparing Standard Solutions
Suitable conductivity standards are available commercially or the user can prepare them
using research grade reagents.
Here are some standard solutions the user can prepare to calibrate the probe of the
model H10C.
1.
Standard solution of 1413uS at 77°F (25°C): Accurately weight out 0.746 grams of
research grade dried Potassium Chloride (KCL). Dissolve in 1000ml of distilled water.
2.
Standard solution of 12.90mS at 77°F (25°C): Accurately weight out 7.4365 grams of
research grade dried Potassium Chloride (KCL). Dissolve in 1000ml of distilled water.
3.
Standard solution of 111.9mS at 77°F (25°C): Accurately weight out 74.264 grams of
research grade dried Potassium Chloride (KCL). Dissolve in 1000ml of distilled water.
[Note: You can store the remaining solution in a plastic container for one week but the
air space between the cap and the solution must be kept to an absolute minimum.
Storing the excess solution below 39°F (4°C) can increase the storage life. If you have
any doubt of the accuracy of the stored solution, a fresh batch should be prepared.]
B. Calibration
Calibration setup contains five sections: TDS, Cell, Temperature Coefficient,
Temperature reference and Conductivity Calibration. To access these sections:
1.
Connect the conductivity probe, PN 2008210, to the unit and turn the unit on. The
screen will display CELL and the cell constant of the conductivity probe.
2.
Allow temperature reading to stabilize, press “Cal” key to enter the calibration
mode. CAL appears on the LCD. Press “Mode” key to sequentially display the
following sections:
[Note: Press “Enter” key to accept any values changes in each section and automatically
advance to the next section. If there are no changes, the unit accepts the current value
and proceeds to the next section.]
a.
TDS
TDS is determined by multiplying conductivity (mS) by a TDS factor. The default factor
value is 0.65. To change the TDS factor, use the up and down keys to adjust the value
between 0.30 and 1.00. Press “Enter” key to save the new value, or press “Mode” key to
cancel the change and display the CELL screen.