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Determining Air and Water Weights
Air and water weight measurements are provided for the Profiler by McLane.
A
complete description is also included here to provide an understanding of the process and the
accuracy requirements. Contact McLane for a re-ballast if required.
The air weight should be measured on a scale with an accuracy of ± 10 gram
(10g).
Accuracy of the water weight measurement may be affected by microscopic bubbles on
the exposed surfaces of the MMP. A continuous sheet of bubbles can coat the MMP within a few
minutes of immersion. Submerging the Profiler to a depth of two meters or more prevents bubble
formation. The presence of bubbles adds a significant amount of buoyancy to the profiler and
invalidates the weight measurement.
In addition, the density of the MMP has a distinct temperature dependence. Changes
occur in the MMP water weight during temperature equilibration. A plot of these changes over a
five hour period is shown in Figure 6.1-1. In this case the water temperature was approximately
18°C and the initial temperature of the MMP was approximately 25°C. The ultimate change in
weight was approximately 40 g (out of a total mass of ~70000 g) or 6 g/°C.
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