4 calibration with standard solution, 4 calibration with standard solution -4 – Yokogawa SC72 Personal Handheld Conductivity Meter User Manual

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5-4

5. Handling of the SC72 Personal Conductivity Meter

5.4 Calibration with Standard Solution

Note:

Calibration with standard solution means to measure a standard solution of
accurately-known conductivity and to adjust SC72 meter so that the displayed
measured value is the same as the known conductivity value of the standard
solution.

If the sensor has been used for a long time, and does not look clean despite washing,
recalibrate the SC72 meter with standard solution to check if cell constant is normal.

If “

” occurs during calibration with standard solution, replace the sensor.

Note that if calibration with the standard solution shows that the cell constant has
changed, update the cell constant value on the sensor cable with the new data.

Notes for calibration with standard solution:

Types of standard solution

Use NaCl (sodium chloride) or KCl (potassium chloride) solutions.

(1) NaCl (sodium chloride) solution

When NaCl solution is used, the temperature coefficient of NaCl is built into the
temperature compensation functions of the meter so conductivity converted to 25

؇C can

be readily obtained regardless of liquid temperature. Standard NaCl solution of 0.1 mol/l
(normal unit expressing concentration of solution) is available as an option from
Yokogawa. For more details, see Section 1.7.

When the sensor for high purity water measurement is used, dilute the standard solution
with pure water to obtain 0.001 ml/l solution of conductivity 1

␮S/cm. Conductivity is as

follows:

0.1 mol - NaCl solution: conductivity 10.67 mS/cm at 25

؇C

0.001 mol/l - NaCl:

conductivity 123.9

␮S/cm at 25؇C

(2) KCl solution

Table 5.2 describes how to make KCl solution of different concentrations, and lists their
conductivities.

Table 5.2

How to make KCl solutions, and their conductivities
(based on JIS K 0102)

KCl

solution

65176

7138

773.8

97838

11167

1220.5

111342

12856

1408.8

146.93

KCl standard solution,

␮

S/cm

T0502.EPS

How to make

Dissolve 74.2460g of KCl in water to

get 1l at 20

Dissolve 7.4365g of KCl in water to get

1l at 20

Dissolve 0.7440g of KCl in water to get

1l at 20

Dissolve 100ml of standard solution C

avobe in water to get 1l at 20