User manual

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11.6. Negative
The function aids previewing mass value and other indications on the display. Depending
on user needs it is possible to enable or disable the function.
11.7. Air buoyancy correction
The air buoyancy correction enables correcting errors occurring while mass measuring
processes, i.e.:
1.
Determining mass of a sample which density considerably differs from the density of
a mass standard used for adjusting the balance. As standard, the balance is adjusted
with a mass standard made of steel that density equals ~8.0g/cm
3
or made of brass
with density ~8.7g/cm
3
. If the weighed object is made of other materials, then below
specified relationship applies:
Below scheme demonstrates the size of mass corrections in relation to the density of
weighed material, and assuming that air density is constant and equals 1.2 kg/m
3
.
Fig. 28. Error value in relation to the density of weighed sample
2. The test monitors changes in mass of a sample within the time of a few hours, if:
mass sample is possibly constant (minor changes). In such case it is assumed, that
considerable effect on the final mass measurement result is caused by changes of air
density, which in turn is strongly affected by pressure, temperature and humidity.
In order to make the measurements reliable, it is necessary to determine the density
of air in the weighing room and the density of weighed object.