User manual

16 PBS-A03/A04-BA-e-1213
ρ =
A
A-B
o
ρ
6 Preconditions for Precise Measurements
There are numerous error possibilities during density determination.
Accurate knowledge and caution are required to achieve precise results when
applying this density set in combination with the balance.
6.1 Calculation of Results
The balance displays results for density determination by giving four decimal places.
However, this does not mean that the results are accurate down to the last decimal
place as this would be the case for a calculated value. Therefore all weighing results
used for calculations have to be examined closely.
Example for density determination of solids:
To ensure high-grade results, numerators as well as common denominators of the
formula below must show the desired accuracy. If either of them is instable or flawed,
the result, too, will be instable or flawed.
ρ = density of sample
A = weight of the sample in air
B = weight of sample in measuring fluid
ρ
o
= density of measuring fluid
The use of a heavy sample contributes to the accuracy of a result. this increases the
numerical value. The use of a light-weight sample, too, contributes to the accuracy of
a result because this increases buoyancy (A-B). As a consequence, the result of the
common denominator increases. Bear also in mind that the accuracy of the density of
the measuring fluid ρ
o
enters into the common denominator and, thus, has
considerable influence on the accuracy of the result.
The result for the density of the sample cannot be more accurate than the least
accurate of the aforementioned individual entities.