YOKOGAWA PH72, Руководство пользователя

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IM 12B03D02-01E
8-2
8 . ORP Meter
8.2 Maintenance of ORP Sensors
Maintenance of ORP sensors is in accordance with that of pH sensors (refer to
Chapter 6, “Maintenance”).
Cleaning the Platinum Electrode and Liquid Junction
Dirt or deposits on the platinum electrode or liquid junction may interfere with accurate
measurement. Periodical cleaning is required depending on the nature of the solution
being measured.
As in the same manner for pH sensors, use a cotton swab or brush to clean (see
Section 6.2). If the potential is outside the tolerance after the sensor check has
been performed according to the procedure in Section 8.3, clean the platinum of the
sensing electrode.
Polish the platinum using a cream cleanser, alumina powder, or baking soda (sodium
bicarbonate), and then wash with water.
CAUTION
Do not apply physical shock or excessive force to the glass sensor, or it may break.
Replenishment of Electrode Filling Solution
When the level of KCl filling solution drops, replenish following the procedure in
Section 6.6.
8.3 Checking the ORP Sensor
Use a check solution to verify that the ORP sensor operates properly. The oxidation-
reduction potential of the check solution to be used should have been correctly
determined by a normal ORP sensor. The following explains how to check an ORP
sensor using a quinhydrone reagent (spare part).
Preparing a Quinhydrone Solution
Prepare a 250 mL solution in a wide mouthed bottle by dissolving one pack of
quinhydrone reagent in deionized water. If the temperature of deionized water is low,
the reagent may not be dissolved completely and some powder may float on the
surface of the solution. This will not affect the ability of the solution. A quinhydrone
solution may change with time, so it should be prepared and used within the same
day.
Procedure
(1) Pour 50 to 100 mL of the prepared check solution into a clean container (200
mL).