Delta OHM HD 98569, Руководство пользователя

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pH, conductivity and dissolved Oxygen measurements - Most frequent
problems, possible causes and handling
Instrument functioning
•
When selecting some functions the “Operation reserved to the administrator” message is
displayed on the screen
.
Some instrument functions are reserved to the user registered as "Administrator". The other users
cannot execute them (see the details on page
17
).
•
Clicking on the LOG key the “Logging disabled!” message is displayed on the screen
.
The logging interval was set to 0. To enable it, open the menu “System Parameters >> Memory
and Logging Options >> Log Interval”, and select a log interval different from zero.
pH measurement
The average life of a pH electrode is about one year according to the use and maintenance
performed.
The electrodes used at high temperatures or in highly alkaline environments have a shorter life.
It is recommended to condition the new electrodes for half day by immersing them, before use, into
a buffer at 6.86pH or 4pH.
Calibrate the electrode with solutions closer to the values being measured. A new electrode must
always be calibrated at neutral pH (6.86pH) as first point, and at least on an acid or alkaline
second point.
Generally, the pH electrodes have a body in glass: handle them with care to avoid breakage. In
particular, the membrane (the sensitive element housed in the end part of the electrode) is made of
very thin glass.
Some of the most frequent problems and their possible solutions are reported below.
Wrong pH measurement
. Carry out the following checks:
ƒ Check that the diaphragm is not obstructed and possibly clean it using the HD62PT
solution.
ƒ Check that the reference system is not contaminated. In case of a filling type electrode,
replace the electrolyte with the suitable solution.
ƒ
Check that no air bubbles are present in the electrode tip and that it is sufficiently
immersed.
Dirt residuals deposited on the membrane can alter the measurement: use the
HD62PP
solution
for protein cleaning.
Slow response or wrong measurements
. Possible causes are aging, or erosion of the
membrane, or a short circuit in the connector.
Storage.
Keep the electrode immersed in the HD62SC solution.
Conductivity measurement
The service life of a cell can be unlimited, provided that the necessary maintenance is performed
and that it does not break. Some of the most frequent problems and their possible solutions are
reported below.
Measurement of conductivity different from the expected value
.
Check that the probe is connected to the correct input: Input
χ
.