Calibration - HACH LANGE sensION+ EC 7 Manuel D'utilisateur

4. Operation

4.4. Calibration

This process involves adjusting the values read by a conductivity
measuring system (instrument and cell) according to the values
of standard solutions.
Calibration is very important for highly accurate readings.
The equipment is capable of one-, two- and three-point calibra-
tion using 147µS/cm, 1413 µS/cm, 12.88 mS/cm and 111.8 mS/
cm standards.
The calibration parameters are stored in the memory until a new
calibration is performed.
It is recommended to use the standards with values closest to the
expected one in the samples.
One-point calibration
This form of calibration is used when measuring conductivity
values around that of the standard used.
This is the most common type of calibration. In this type, 1413
µS/cm is the most commonly-used standard.
Two-point calibration
This type of calibration is recommended for work in high or low
conductivity regions where accuracy is required.
If you are calibrating with more than one standard, it is necessary
to start with the one with the lowest conductivity to avoid conta-
mination problems.
Three-point calibration
This type of calibration is recommended when the conductivity
of the samples to be measured ranges from low to high.
If you are calibrating with more than one standard, it is necessary
to start with the one with the lowest conductivity to avoid conta-
mination problems.
Calibration data
They can be viewed at any moment. See diagram.
Calibration frequency
Select between 0 and 99 days. The instrument by default is
programmed for calibration every 15 days, and indicates the
remaining time to the new calibration.
Selecting 0 h the automatic re-calibration warning is deacti-
vated.
Theoretical calibration
Selecting "theoretical calibration" the calibration data of the cell
in use are replaced by C=1.000 cm
This step is prior to the obtention of a calibration certificate.
C introduction
Manual introduction of the cell constant. Useful when the cell
was previously calibrated, for example in calibration laboratory.
Press at any point to exit.
sensION+ EC7 HACH_LANGE 0710.indd ANG:7 sensION+ EC7 HACH_LANGE 0710.indd ANG:7
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Preparation
Fill the flasks with the corresponding standard solution (50 ml.)
The times of use of these standards portions depends on the cell
cleaning. Crison recommends replacing the solution in the flasks
after 2-3 times of usage.
Every calibration flask is supplied with a magnetic bar.
Diagram for calibration
10-04-2010
New CAL. in 7 d
CALIBRATION
EC, press EC
CAL. data, press
C introduct., press
EC CALIBRATION CALIBRATION DATA EC
Last calibration
17:15
Use standard 147 uS P: 147, 1413 and 12.88
C1: 1.023, C2: 1.035
Press
C3: 1.038 cm-1
CAL. FREQUENCY EC
EC CALIBRATION
23.5˚C
147 uS/cm @ 25˚C
Every: 7
Automatic warning.
Time 23 s
3s
1st standard OK THEORETICAL CAL.
23.5˚C
147 uS/cm @ 25˚C
Time 30 s C: 1.000 cm-1
3s
EC CALIBRATION
Use standard 1413 uS
Press
EC CALIBRATION
22.5˚C
1413 uS/cm @ 25˚C
Time 19 s
2nd standard OK
22.5˚C
1413 uS/cm @ 25˚C
Time 24 s
EC CALIBRATION
To use
Use standard 12.88 mS
standard
Press
111.8 mS
To calibrate in 3 points
17:15
23.2˚C
TRef 25˚C
C INTRODUCTION
Nominal value
17-03-07
C=1 cm-1
C=0.1 cm-1
C=10 cm-1
C INTRODUCTION
3s
Nominal value
day C=1 cm-1
C=0.1 cm-1
C=10 cm-1
3s
C INTRODUCTION
Cell constant
C=0.100 cm-1
C INTRODUCTION
Cell constant
C=0.108 cm-1
3s
7
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