BKI 11 ATEX 0012 X
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4.3.
M
AINTENANCE OF THE P
H
AND
ORP
ELECTRODES
In this chapter you can find some recommendations regarding re-hydration, chemical cleaning and reactivation of the electrodes.
Disassembling the electrode
During this operation be careful not to expose the fragile electrode to mechanical (bending,
squeezing, tensile) forces!
Hold the electrode housing with one hand and the flare nut (right-threaded) with the other one
and loosen it completely.
Then detach carefully the electrode housing from the instrument housing.
Loosen the electrode carefully using a socket-wrench (size 17) and screw it off completely.
Don't use a pipe- or a double-end wrench!
Put the electrode into the storage solution or perform the following steps below.
size 17
Re-hydration
If the electrode was desiccated due to incorrect use or storage it needs to be re-hydrated. This has to be done by soaking the electrode in 3mol/l KCl storage solution
at 20°C for 24 hours. The process can be shortened to 6 hours if the KCl solution is at 60°C.
Note: long time desiccation or desiccation after measuring crystallizating mediums may have an irreversible effect on the electrode and thus the re-hydration may not
be successful.
Chemical cleaning
The deposits and obstructions on the surface of the electrode’s membrane and on the diaphragm have to be eliminated from time to time:
1. General deposits
Rinse the electrode with warm water then dry up gently using a soft rag!
Soak the electrode for 15 mins in 1.5mol/l (5%) hydrochloric acid (HCl)!
Rinse the electrode again with warm water then dry up gently using a soft swab!
Soak the electrode for 1 hour in 3mol/l KCl solution then perform the calibration procedure!