Instruction Manual
ION Director®
EN
2021-01-23
31
7
Measurement accuracy
The
ION Director®
gives you the best possible accuracy for a measuring device of this class.
In many trials, the measurement process, the measurement electronics and the mechanical
design have been optimized to such an extent that the
ION Director®
can supply very precise
measurement results. Nevertheless, small measuring tolerances, as they occur in all
measuring devices, cannot be completely avoided.
You as a user can make a significant contribution to achieving the maximum measurement
accuracy the
ION Director®
can offer by ensuring the following optimal starting conditions:
•
Accurate calibration of the dosing pumps involved in the measurement
•
Shortest possible tubes between dosing pumps and
ION Director®
as well as between
reference containers and dosing pumps
•
Careful priming of reference liquid tubes
Under these optimum conditions, a tolerance of approx. 3% (Nitrate approx. 5%) can be
achieved per measurement with respect to the middle of the measuring range.
The measured value resolution is 1ppm (0.1ppm for Nitrate).
7.1
What does the measuring tolerance mean in practice?
On closer consideration, one comes to the conclusion that the previously mentioned
tolerance (potential deviation from the real value) does not have a significant impact on the
application. Why is this so?
•
3% (or 5%) deviation of the measurement result from the real value has no harmful
effects, provided that the target values are in the ideal range.
•
Daily visible fluctuations of the individual parameters are normal and unproblematic,
whereas longer significant overshoots or undershoots of the optimal range may well
be harmful.
•
Many commonly used measuring methods, e.g. test kits, offer at best a reproducibility
of 5% under real conditions, an actual tolerance of 10% or more is not uncommon.
•
When regulating the individual parameters, it is not important that a specific value is
permanently maintained to the ppm level; rather, it is important that the parameters
are within an optimal range.
7.2
Comparison with other measurements
Our investigations have shown that different measuring methods (droplet tests or measuring
devices from various manufacturers) do not provide consistent results.
In most cases, even several successive measurements with the same equipment show more
or less deviating results. It is therefore difficult to judge which result is the "correct" one.