Myron L 9PTK User Manual
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Suppose a measurement at 15°C/59°F is 900 microsiemens of true
uncompensated conductivity.
Using a 442 correction of 10 (degrees below 25) x 1.68% indicates the
solution is reading 16.8% low. For correction, dividing by (.832) yields
1082 microsiemens as a compensated reading.
A KCl correction of 10 (degrees below 25) x 1.9% indicates the solution
is reading 19% low. Dividing by (.81) yields 1111 microsiemens for a
compensated reading. The difference is 29 out of 1082 = 2.7%.
D. A Chart of Comparative Error
In the range of 1000 µS, the error using KCl on a solution that should be
compensated as NaCl or as 442, is illustrated in the graph below.
Users wanting to measure natural water based solutions to 1% would
have to alter the internal compensation to the more suitable preloaded
“442” values or stay close to 25°C. Users who have standardized to KCl-
based compensation may want to stick with it, regardless of increasing
error as you get further from 25°C. The Ultrameter III will provide the
repeatability and convertibility of data necessary for relative values for
process control.