VWR MD 8000 L, Operating Manual

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pH value MD 8000 L
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6.2 pH calibration
6.2.1 Why calibrate?
pH electrodes age. This changes the zero point (asymmetry) and slope of the
pH electrode. As a result, an inexact measured value is displayed. Calibration
determines and stores the current values of the zero point and slope of the
electrode.
Thus, you should calibrate at regular intervals.
6.2.2 When do you have to calibrate?
 Routinely within the framework of the company quality assurance
 When the calibration interval has expired
6.2.3 Carrying out automatic calibration (AutoCal)
Make sure that in the sensor menu, Buffer menu, the buffer set is correctly
selected (see section 11.1.1 S
ETTINGS FOR P
H
MEASUREMENTS
, page 62).
Use one to five buffer solutions of the selected buffer set in any order.
Below, calibration with Technical buffers (TEC) is described. When other buffer
sets are used, other nominal buffer values are displayed. Apart from that, the
procedure is identical.
Temperature
sensor Resolution of
the temp. dis-
play Temp. measurement
yes 0.1 °C Automatic with temperature
sensor
- 1 °C Manual
If single-point calibration was set in the menu, the calibration proce-
dure is automatically finished with the measurement of buffer solu-
tion 1 and the calibration record is displayed.
1. Connect the pH sensor to the meter.
The pH measuring window is displayed.
2. Keep the buffer solutions ready.
When measuring without temperature sensor:
Temper the buffer solutions or measure the current temperature.
3. Start the calibration with
<CAL>
.
The calibration display for the first buffer appears (voltage display).