A complete electrical conductivity measurement system includes an inductive or conductance measuring electrode, cable and measuring instrument. Conductivity electrode with pH electrode is different, because it is stable mechanical performance of materials, so don't need a special part to protect. When choosing conductance electrode need to pay attention to the following items:
1. The electrode measurement range
2. Measurement, in the form of electroconductive or inductive. When using conductivity type electrode, want to choose the appropriate electrode constant "K"
3. Temperature,
4. Related to the mechanical structure of pressure
5. Chemical corrosion resistance
6. Installation structure (thread, flange, three clamp connection, etc.)
All measurement cable must be blocked. Especially for conductivity type electrode (this kind of electrode and have direct contact with the test solution), the conductance value higher than 100 mS, to consider the influence of the cable length and cable cross sectional area, this is because the resistance of the cable in measuring circuits).
For example: the measured value is 100 ms,
The electrode constant K = 1,
Resistance is 10 ohm
Measuring the electrode resistance of 10 ohm with cable 4.76 ohm resistance. Measuring instrument display value eventually become 67.75 mS. In such a case, should use a shorter or cross section larger measurement cable. For inductive electrode, the resistance of the cable shall not affect the measured values.
Measuring instrument is to measure the resistance value of conversion into Siemens units and will rule out front when it comes to various interference factors, such as temperature, alpha value, etc, so as to give the right conductivity value.
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