Myron L PS9TK - Manual (Page 64)

Reference Junction, is of the same construction with a porous plug
in place of a glass barrier to allow the junction fluid to contact the
test solution without significant migration of liquids through the plug
material. Figure 28 shows a typical 2 component pair. Migration does
occur, and this limits the lifetime of a pH junction from depletion of
solution inside the reference junction or from contamination. The
junction may be damaged if dried out because insoluble crystals may
form in a layer, obstructing contact with test solutions.
Glass surface
Figure 30
KCl solution
Electrode wire
Electrode
wire
H + ions
Junction
Plug
4. The Myron L Integral pH Sensor
The sensor in the P
OOL
P
RO
(see Figure 29) is a single construction
in an easily replaceable package. The sensor body holds an oversize
solution supply for long life. The reference junction “wick” is porous to
provide a very stable, low permeable interface, and is located under
the glass pH sensing electrode. This construction combines all the
best features of any pH sensor known.
KCl solution
Figure 31
Junction plug
Platinum button
H + ions
Electrode wires
Glass
Glass
Surface
Figure 28
Figure 29
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