16
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 3175-307A/3175-307.
1.
Standard solution of 1413uS at 25
℃
: 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 25
℃
: 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 25
℃
: 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 4
℃
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 six sections: TDS
Constant, Temperature
Coefficient, Temperature Reference, Probe Basic Cell Constant,
Cell Constant Calibration and K Value Input. To access these
sections:
1.
Connect the conductivity probe to the unit and turn the unit
on.
2.
Allow temperature reading to stabilize, press “
Cal
” key
to
enter the calibration mode.
CAL
appears on the LCD.
[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.
]
