4 Startup procedure
Thermo Scientific
14
50108226_02.2007
4.2 Stirring vessels
You should use stirring vessels which are circular in shape, and made of glass,
nonmagnetic metal or plastic. Wall thicknesses should be of an even thinness. For the
MINI you may also use cuvettes.
Flat-bottomed glass vessels (not concave) and smooth surfaces improve the running
quality of the magnetic stirring bars. When stirring larger volumes of liquid, you should
use stirring vessels having a relatively small diameter with a thin bottom.
4.3 Magnetic stirring bars
We recommend using PTFE coated magnetic stirring bars supplied by THERMO
SCIENTIFIC. The bars are made from AlNiCo5 magnets or high performance rare-earth
permanent magnets. The following sizes are suitable:
Thermo Scientific recommends the following magnetic stirring bars:
Type
Size (mm)
Material
Order No.
KOMET 15
KOMET 30
KOMET 50
(Ø x L) 9 x 15
(Ø x L) 12 x 30
(Ø x L) 21 x 50
SmCo
50087924
50087930
50087909
Table 2: Magnetic stirring bars
INFORMATION
Some magnetic stirring bars (especially triangular bars) may have a
critical resonance frequency at lower rotation speeds. This may cause
the magnetic stirring bar to wander away from the turning center and
carry out periodic oscillations. Avoid this rotation speed setting when
the problem occurs. Quickly travel through this problem range when
adjusting the rotation speed.
INFORMATION
In the case of circular and triangular magnetic stirring bars, the length
must not exceed 50 mm. The length of the magnetic stirring bars must
not exceed 80 % of the vessel diameter. Do not use cylindrical stirring
bars with a center ring, or elliptical stirring bars with a round cross-
section.
