Yokogawa 2-Wire Dual Channel Transmitter/Analyzer FLXA21 - Manual (Page 219)

<Appendix 2 For SC (Conductivity)>
App.2-3
IM 12A01A02-01E 5th Edition : Oct. 31, 2013-00
<Calculation example>
Calculate the temperature coefficient of a liquid from the following data.
Conductivity 124.5 µS/cm at a liquid temperature of 18.0 °C and a conductivity 147.6 µS/cm
at a liquid temperature of 31.0 °C.
Substituting the data in the above formula gives the following result.
147.6 - 124.5
x 100= 1.298 %/°C α =
124.5x(31.0 - 25) - 147.6x(18.0 - 25)
Set the temperature coefficient in the FLXA21 converter.
When the temperature coefficient already set is accurate, the conductivity to be displayed
must be constant regardless of liquid temperature. The following check will make sure that the
temperature coefficient already set is accurate.
If, when the liquid temperature is lowered, a larger conductivity value is indicated, the
temperature coefficient already set is too small.
The opposite also applies. If a smaller conductivity value is indicated, the temperature coefficient
already set is too large. In either case, change the temperature coefficient so that the conductivity
no longer changes.
l Matrix
Matrix means temperature compensation with the temperature compensation matrix.
The temperature compensation matrix is a table of conductivity values at different temperatures
and concentrations.
Ready-made matrixes and user-defined matrixes are available.
<Ready-made matrixes>
Ready-made temperature compensation matrixes are available for common inorganic acids and
bases. Those for ammonia and morpholine are also available.
Table 2 Ready-made temperature compensation matrixes
Matrix
Compound to
be measured Concentration
Temp. compensation
range
Details
Ammonia 0..50ppb Ammonia 0 to 50 ppb 0 to 90˚C Table A
Ammonia 15..30% Ammonia 15 to 30% 10 to 50˚C Table B
Morpholine 0..500ppb Morpholine 0 to 500 ppb 0 to 90˚C Table C
Sulfunic acid 0..27% H
2
SO
4
0 to 27% 0 to 100˚C Table D
Sulfunic acid 39..85% H
2
SO
4
39 to 85% -18 to 116˚C Table E
Sulfunic acid 93..100% H
2
SO
4
93 to 100% 10 to 90˚C Table F
NaOH 0..15% NaOH 0 to 15% 0 to 100˚C Table G
NaOH 25..50% NaOH 25 to 50% 0 to 80˚C Table H
HCl 0..200ppb HCl 0 to 200 ppb 0 to 100˚C Table I
HCl 0..18% HCI 0 to 18% -10 to 65˚C Table J
HCl 24..44% HCI 24 to 44% -20 to 65˚C Table K
HNO
3
0..25% HNO
3
0 to 25% 0 to 80˚C Table L
HNO
3
35..80% HNO
3
35 to 80% -16 to 60˚C Table M
The ready-made temperature compensation matrixes are listed in Table A to M where
temperatures are in the column and concentrations are in the rows.
App.
SC