22
7.
Rinse the pH and Conductivity or Temperature sensors in distilled water and blot them dry.
8.
Place both sensors into a small sample of secondary buffer (pH4.01, 9.18 or 10.01), so that the
bulb and reference junction are both covered as per the diagram in step 5.
DO NOT
place the sensors directly into the buffer bottle.
pH9.18 and pH10.01 buffers are unstable once the bottles have been opened. Discard
immediately after use
.
9.
Select pH calibration (
→
→
→
→
F1:Calibrate
→
→
→
→
F3:pH
).
The display should now look similar to the example shown in step 6. Note that the
90-FLMV
has automatically recognised the second buffer.
Wait for the displayed reading to stabilise before attempting to calibrate the
90-FLMV
.
Press
to calibrate to the displayed buffer.
Otherwise, enter an alternative buffer using the Numeric Keypad, and then press
.
10.
The
90-FLMV
is now pH calibrated and is ready for use in this mode. Discard the used
samples of buffer.
Rinse the pH and Conductivity or Temperature sensors in distilled water and blot them dry
before placing them into unknown samples.
7.3 pH Calibration Notes
1.
A 1-point calibration should be performed at least weekly. In applications where the sensor
junction can become blocked such as dairy products, mining slurries etc, a 1-point calibration
may have to be done daily.
2.
A 2-point calibration should be performed at least monthly. Of course, more frequent
calibration will result in greater confidence in results.
3.
All calibration information is retained in memory when the
90-FLMV
is switched off, even
when the power supply is removed. This information can be recalled or printed later using the
GLP function (see section 10).
