KERN & SOHN AET 200-4NM - Manual (Page 26)

26 AET_/PET_/ILT_NM-BA-e-1410
The application enables correcting mass measurement errors during:
1. Weighing loads that density considerably differs from the density of
standard used to adjusting the balance. Regularly, the balance is adjusted
with a steel mass standard with density ~8.0g/cm 3 or a brass mass
standard with density ~8.7g/cm 3 . If loads made of other substances are
weighed, then ratio indicated on below chart should apply.
Below chart presents the value of mass correction in relation to the density
of weighed load, assuming that air density is constant and equals
1.2 kg/m 3 .
C
or
rec
ti
on v
al
u
e [
m
g
]
D
ens
it
y
of
w
ei
g
hed
l
oa
d
Sample mass [g]
Error value in relation to density of weighed sample
2. Testing the changes of sample mass within a few hours’ time, if: sample
mass is relatively constant (minor changes). In such case it is assumed,
that considerable effect on the measurement result rests on air density
changes, which is affected by changes of pressure, temperature and
humidity.
In order to carry out a reliable measurement, apart from being familiar with
relations applying to ambient conditions, an operator should know the measuring
methods, features of tested sample, air density in the laboratory room and
density of weighed sample.
FUNCTIONING
The application provides two ways to use the air buoyancy correction procedure.