Yokogawa 2-Wire Dual Channel Transmitter/Analyzer FLXA21 - Manual (Page 188)

<16. COMMISSIONING OF SENCOM pH/ORP>
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IM 12A01A02-01E 5th Edition : Oct. 31, 2013-00
n Temperature compensation
This compensation of pH value is performed on the Nernst equation.
Two methods can be used: Automatic and Manual. Select Automatic when a temperature
element is used, or select Manual when a manually set temperature is used.
NOTE
When Manual is selected on the Temperature compensation, a process temperature should
be set in the “Manual temp.” A temperature shown on the Main display is this manually set
temperature.
n Reference temperature
Set a reference temperature to which the measured pH value must be compensated. Normally
25°C is used, so this temperature is chosen as the default value.
n Process temperature compensation
Select a temperature compensation method. “None” does not perform the temperature
compensation.
If “pH” is selected in “Sensor type,” choose process temperature compensation from among
None, TC, Matrix, and NEN6411. If “ORP” is selected in “Sensor type,” choose it from among
None and TC.
l
TC
This method uses the linear compensation function.
It is possible to adjust the temperature coefficient (TC) factor directly. If the temperature
coefficient factor of the sample liquid is known from laboratory experiments or has been
previously determined, it can be entered here.
This TC is a pH variation to 1 °C (∆pH/∆T). Adjust the value between -0.1 to 0.1 pH/ºC.
In combination with the reference temperature setting, a linear compensation function is
obtained, which is suitable for all kinds of chemical solutions.
l
Matrix
Matrix means a temperature compensation which uses the temperature compensation
matrix. The temperature compensation matrix is a table of pH values at various temperatures
corresponding to the pH values at the standard temperature. For details, see Appendix 1.
When the temperature or the precompensated pH value is out of the range of the temperature
compensation matrix, the temperature compensation error (warning) will be issued. This is not a
device error.
In this case, however, the temperature compensation is performed by extrapolation.
NOTE
To display the precompensated pH value, set the Process Temp. Compensation to “None”.
Select Measurement setup → Temp. compensation → Process Temp. Compensation.
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