4 calibration with standard solution, 4 calibration with standard solution -4 – Yokogawa SC72 Personal Handheld Conductivity Meter User Manual
Page 47
IM 12D03D02-01E
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
A
B
C
D
0
؇
C
65176
7138
773.8
18
؇
C
97838
11167
1220.5
25
؇
C
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
؎
1
؇
C.
Dissolve 7.4365g of KCl in water to get
1l at 20
؎
1
؇
C.
Dissolve 0.7440g of KCl in water to get
1l at 20
؎
1
؇
C.
Dissolve 100ml of standard solution C
avobe in water to get 1l at 20
؎
1
؇
C.