Myron-l TH1 User Manual download pdf (Page 35)

Figure 15 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.

(ref. pH, pg. 20).

D. Myron L Integral pH Sensor (TPH1 & TH1)

The sensor in the TechPro II (see gure 16)

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 formed in a

ring around the pH sensing electrode.

This construction combines all the best

features of any pH sensor known.

E. Sources of Error (TPH1 & TH1)

The basics are presented in pH, pg. 20.

1. Reference Junction

The most common sensor problem will be a clogged junction because a

sensor was allowed to dry out. The symptom is a drift in the “zero” setting

at 7 pH. This is why the TechPro II does not allow more than 1 pH unit of

offset during calibration. At that point the junction is unreliable.

2. Sensitivity Problems

Sensitivity is the receptiveness of the glass surface. A lm on the surface

can diminish sensitivity and cause a long response time.

3. Temperature Compensation

pH sensor glass changes its sensitivity slightly with temperature, so the

further from pH 7 one is, the more effect will be seen. A pH of 11 at

40°C would be off by 0.2 units. The TechPro II senses the sensor well

temperature and compensates the reading.

KCl solution

Figure 16

Junction plug

Electrode wires

Glass

Sleeve

Glass Surface

Glass surface

Figure 15

KCl solution

Electrode wire

ions

Junction Plug

1 2 ... 30 31 32 33 34 35 36 37 38 39 40 ... 43 44

Comments to this Manuals

No comments

Myron-l TH1 User Manual Page 35

Comments to this Manuals

Related products and manuals for Tools Myron-l TH1