8
B. Conductivity Measurements
1.
Turn the unit on. Place the probe in the solution to be
measured. Immerse the probe (at least 2” to 3” or 5~7cm from
the tip). Shake the probe lightly to remove any trapped air
bubbles in the conductivity cell.
2.
Press
“Mode”
key to enter the desired measurement mode
(Conductivity, TDS or Salinity). The message “over” or “undr”
may appear briefly on the display indicate auto-ranging; this is
normal. Allow temperature to stabilize before taking
measurements.
C. 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 3177.
1. Standard solution of 1413 uS/cm at 25
℃
: Accurately weight
out 0.746 grams of research grade dried Potassium Chloride
(KCL). Dissolve in 1000 ml of distilled water.
2. Standard solution of 12.90 mS/cm at 25
℃
: Accurately weight
out 7.4365 grams of research grade dried Potassium Chloride
(KCL). Dissolve in 1000 ml of distilled water.
3. Standard solution of 111.9 mS/cm at 25
℃
: Accurately weight
out 74.264 grams of research grade dried Potassium Chloride
(KCL). Dissolve in 1000 ml of distilled water.
[Note:
You can store the unused portion of the standard
solution in a plastic container for six months 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.
]
