4 The Instrument - An Overview
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Note that the accuracy of the concentration measurement depends on the
accuracy of the instrument, but also on the slope of the density/concentration
correlation. This means, for example, that a density measurement with an
accuracy of ±0.00001 g/cm
3
will be converted into an ethanol value with a
significantly smaller accuracy of ±0.025 % w/w. The accuracy of some typical
concentration measurements is given in Appendix A.1.
4 The Instrument - An Overview
The DMA M series instruments are density and concentration meters that were
developed to combine highest precision with easy operation and robust design.
The measurement is based on the oscillating U-tube method which was invented
by Dr. Hans Stabinger and Dr. Hans Leopold at the Joanneum Research Institute
(Graz, Austria) and first introduced onto the market by Anton Paar in 1967.
Features and Benefits
Accuracy
Your DMA M series instrument is equipped with the world’s most advanced digital
density measurement technology:
•
The period of oscillation of the U-tube is measured by optical pickups.
•
Two integrated Pt 100 platinum thermometers together with Peltier elements
provide an extremely precise thermostatting of the sample.
•
ThermoBalance
TM
: An additional reference oscillator provides long-term
stability and enables precise measurements over the whole temperature
range of the instrument with only one adjustment at 20 °C.
•
Viscosity-related errors are automatically corrected over the full viscosity
range by measuring the damping effect of the viscous sample followed by a
mathematical correction of the density value.
•
In the DMA 5000 M, special adjustments with standards of high viscosity and
high density lead to an enhanced precision for samples with high viscosity
and high density.
Error detection
A major source of measuring errors when using density meters are gas bubbles
in the measuring cell. This issue was addressed by Anton Paar with two new
features:
