Use Of Air Buoyancy Compensation Factor - RADWAG UYA 4Y.PLUS Ultra-Microbalances Manuel De L'utilisateur

3. when the tare value exceeds 2% of the maximum capacity, Err message is displayed in order to
inform you about the fact that operation cannot be carried out.
Procedure 3 - when the tared load is on the weighing pan or upon taking the tared load off the
weighing pan:
1. press < Deactivate tare> programmable button,
2. the NET marker is deleted,
3. the display indicates tare value,
4. to restore the last tare value press <

15.6. Use of Air Buoyancy Compensation Factor

The application enables correcting mass measurement errors in the course of:
1. weighing loads of density considerably different from the density of standard that has been used to
adjust the balance; typically the balance is adjusted with a steel mass standard of ~8.0g/cm
density or a brass mass standard of ~8.7g/cm
weighed, then ratio indicated on below graph applies;
Error value versus density of weighed sample
2. testing sample mass change within a few hours long period of time for a case when the sample
mass is relatively constant (minor changes); it is assumed that air density changes affect the final
result considerably, wherein the density is influenced by changes of pressure, temperature and
humidity.
In order to carry out a reliable measurement it is necessary to know the measuring methods, features
of tested sample, ambient conditions, air density in the laboratory room and density of weighed
sample.
Functioning
The air buoyancy compensation procedure is to be used as follows:
1. Method 1:
Enter air density value and value of weighed sample density to balance memory.
Wait, the software automatically calculates the correction factor for weighed mass, next corrected
value of weighed mass is displayed.
In order to avoid mistakes, the corrected mass value is accompanied by <
visible on a display and a printout.
2. Method 2:
Determine air density value with use of balance program (semi-automatic operation) and enter
value of weighed sample density to balance memory.
Determination of air density is carried out using a set of two mass standards, one made of
stainless steel, and the other one of aluminium. Based on mass indications of the two standards,
Restore tare> button.
3
density; if loads made of other substances are
The
values for versus the density of
weighed load, assumption that air
density is constant and equals 1.2
3
kg/m
- 63 -
graph presents correction
is taken.
!
> symbol, the symbol is
3