11
Calibration with Nist Standard (if you have NIST buffer solution)
10.15 Make sure the unit is properly installed and electrode connected.
10.16 Press
and display will show
CAL
CAL
CAL
CAL
flashing on the left,
indicating it is in calibration mode.
10.17 This meter has an internal setting of automatic buffer recognition on
the Nist Standard.
Always begin with “Offset” calibration first
.
10.18 Rinse the pH electrodes in distilled water then dip in the buffer
solution. First Offset buffer (pH6.86) then subsequently slope buffer.
10.19 Main display will show the current measured value and the bottom
sub-display will show the buffer value. Value will vary according to
temperature listed below table:
NIST standard buffer solution
Temperature
(°C)
Slope
1.68
Slope
4.01
Offset
6.86
Slope
9.18
Slope
12.45
0
1.67
4.01
6.98
9.47
13.43
5
1.67
4.00
6.95
9.38
13.21
10
1.67
4.00
6.92
9.32
13.00
15
1.67
4.00
6.90
9.27
12.81
20
1.68
4.00
6.88
9.22
12.63
25
1.68
4.01
6.86
9.18
12.45
30
1.69
4.01
6.85
9.14
12.29
35
1.69
4.02
6.84
9.10
12.13
40
1.70
4.03
6.84
9.07
11.99
45
1.70
4.04
6.83
9.04
11.84
50
1.71
4.06
6.83
9.01
11.70
10.20 If the sub-display does not automatically recognize a buffer, it means
the electrode could be defective or the buffer solution is wrong.
Calibration cannot proceed until they are rectified.
10.21 When the
READY
sign appear on the top left corner, it means you are
ready to confirm the setting. Wait another 10 seconds, if the reading
is not stable,
READY
sign will disappear. Wait again till it appears.
10.22 Press
to
to confirm and display will flash and reading will revert
to raw data, while sub-display alternate between buffer standard.
10.23 Repeat step 10.18 to 10.22 subsequently up to 4 Slope calibrations.
10.24 After confirming the final calibration point, press
to
exit
calibration mode and return to normal reading.
Always rinses the electrode with distilled water before and after each
test. This is to prevent solution carry over or cross contamination.
Standard solutions must maintain highest purity; otherwise the
meter’s accuracy could be compromised.
