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(4)
Refill the tank with 3.3 mol/L KCl solution (see Figure 3.3). The maximum solution level is 30 to
40 mm lower than the top.
Figure 3.3
(5)
Retighten the nut to fix the cap in position. Connect the socket type connector and apply air
pressure to the tank.
(6)
Open the valve and let the measured solution flow through the holder.
3.1.4 Cleaning the Glass Electrode and Liquid Junction
Staining of the glass electrode or liquid junction can cause measurement error. Consequently, if
the measured solution tends to stain the electrode, the glass electrode and liquid junction must be
cleaned periodically, the period depending on the degree of staining.
Clean the glass electrode and liquid junction as per the following procedure:
●
Stains due to suspended solids, sticky material or microbes, etc.
Using soft tissue paper, wipe the stains off the glass electrode and liquid junction.
Further, clean off the remaining stains by rinsing with water,
●
Stains due to oily material.
Wash off the stains by submerging in a neutral detergent solution in a beaker, etc.
●
Chemical stains such as due to metallic adsorption.
Submerge the "glass electrode" and the "liquid junction" in a diluted hydrochloric acid solution (1
to 2%) for several minutes (acid washing).
If the sensor characteristics are affected by chemical staining, e.g. when the sensor is used for pH
measurement of a highly alkaline solution, carry out acid washing.
30 to 40 mm
F3.3E.ai
Maximum KCl Replenishment Level
< 3. USE OF pH SENSOR >
IM 12B7J3-01E
3-3
7th Edition : Nov.20,2018-00
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