Table of Contents
Advertisement
3.
Maintenance on operation
3.1
Operation and Periodic Maintenance
3.1.1
Calibrating ORP Sensor Using Checking Solutions
Dirt attached to the liquid junction or sensitive parts (platinum electrodes) may have an adverse
effect on electromotive force and response characteristics, so ORP sensors require periodic
cleaning for good operating conditions. ORP sensors should be checked and calibrated if the
following conditions are met.
(1) Sensor checks
• If a new ORP sensor is used or the existing sensor has been unused for an extended period
of time.
• When an ORP sensor sensitive part (platinum electrode) or a liquid junction is cleaned.
(2) Calibration
• If sensor electromotive force is outside the allowable ranges.
• If the measured value by the ORP sensor is adjusted to the measured value by other
sensors.
For more detailed information on the calibration procedures, see the separate Instruction
Manuals "Two-wire Liquid Analyzer" (publication no. IM 12A01A02-01E) and "Four-wire pH/ORP
Converter" (publication no. IM 12B07C05-01E).
3.1.2
Cleaning Indicator Electrode and Liquid Junction
Staining of a indicator electrode or liquid junction can cause measurement errors. Therefore, if he
measured solutions tend to stain the electrode, the indicator electrode and liquid junction must
be cleaned periodically - depending on the degree of staining. if the ORP Sensor is installed in a
holder with a cleaner, the sensor is continuously (for an ultrasonic cleaner) or intermittently (for a
jet or brush cleaner) cleaned automatically.
Because of this, sensor cleaning is not usually required.
To clean the indicator electrode or liquid junction, proceed as follows:
●
Stains due to suspended Solids, Sticky Materials, Microbes or the like
Using soft tissue paper, wipe the stains off the indicator electrode or liquid junction. In
addition, clean off remaining stains by rinsing with water.
●
Stains due to Oily Materials
Wash off stains by submerging in a neutral detergent solution in a beaker, etc, (for from
several tens of minutes to several hours depending on the degree of staining).
●
Chemical Stains such as due to Metallic Adsorption
Place the indicator electrode or liquid junction in a diluted hydrochloric acid solution (1 to
2%) for several minutes (acid washing).
3.1.3
Refilling Sensor with KCl Solution
The concentration of the KCl solution in the sensor will begin to drop when the saturated
concentration cannot be maintained with the KCl solution from the liquid junction. As the
concentration of the KCl solution decreases, so too does this influence the sensor's performance.
To avoid this, replenish the KCl solution in the sensor before the concentration starts to decrease.
< 3. Maintenance on operation >
IM 12C04K01-01E
3-1
7th Edition : Feb.20,2020-00
Advertisement
Table of Contents
