Myron L 9PTK User Manual

Page 67

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 33 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.

4. The Myron L Integral pH Sensor

The sensor in the Ultrameter III (see Figure 34) 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.