Test summary
Portable
water activity
measuring instruments
EminTech
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Importance of validation | |
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The tests of the three water activity measurement instruments clearly demonstrated the importance of result validation. Without calibration all three instruments would have given erroneous measurement results already after three weeks.. Two of the three tested sensors gave significantly different measurement results after some time of testing. At least initially, before the properties of an instrument is known, it is recommended to validate the readings before and after each measurement, or at least once a day. Decagon recommends validation once a week and sell highly advised calibration ampoules in packages of 50 for one year supply. |
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HygroPalm AW1 with sample cell AwVC-DIO | |
| performed very well during the measurements. The results showed only small variations. In case analysis time should be important, the extrapolation function appeared to work well, although several consecutive measurements increased the reliability of the results. The only major flaw, the battery problem, may be solved using battery switching routines, an optional docking station or upgrading to Rotronic HygroLab. Also the price of this instrument was attractive. |
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Decagon Pawkit | |
| This pleasant little instrument showed an initial instability but appeared to give stable results after calibration. If portability is important this instrument well worth consideration. The good manual and the dedicated Swedish agent provide additional arguments for this device (in Sweden). |
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Testo 650 with sample cell 0628.0024 | |
| was the most expensive instrument in the survey. As calibration instructions are charged extra, the price became even higher. In spite of the impressing documentation provided, the instrument did not deliver measurement results as expected. In case additional features should be used, like connecting other sensors to the instrument, this instrument may be worth consideration. |
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