6 Stirring operation
50134805_03.2012
15
Thermo Scientific
6.2
Magnetic stirring bars
INFORMATION
Use only suitable and undamaged magnetic stirrers! Check the stirring
bar before use for signs of damage (cracks, chips ... etc.)
Thermo
recommends the following magnetic stirring bars:
Typ
Size (mm)
Material
Order No.
KOMET 90
(Ø x L) 24 x 90
SmCo
50087902
Twin magnetic
stirring bar
(L x B x H) 90 x 81 x 30
Rührstäbe: KOMET 90
SmCo
50087868
Magnetic stirring
bar with bearing
(Ø x H) 146 x 48
stirring bar: KOMET 90
SmCo
50087869
INFORMATION
The length of the magnetic stirring bar (2) must be smaller than the
diameter of the magnetic coupling (tech. specification).
INFORMATION
Some magnetic stirring bars (2) (especially triangular bars) may have a
critical resonance frequency at lower rotation speeds. This may cause
the magnetic stirring bar (2) 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.
Thermo
has developed a new magnetic stirring bar
KOMET 90
(Figure 2). It contains a high-quality super-strong samarium-cobalt magnet.
KOMET 90 shows a strong magnetic force. The stronger attraction to the magnetic
alternating field provides the stirring bar with very efficient stirring properties. Even if
there are greater distances (e.g. in high measuring cylinders) the stirring force will be
maintained. The stability of the stirring bar will not be impaired if the vessel has a
curved bottom. The strong magnetic coupling in samarium-cobalt magnets will also
increase friction. The standard design of the KOMET magnetic stirring bar is therefore
unsuitable for stirring liquids containing particulate matter (such as mud) or for stirring in
vessels with a rough interior surface. Some of the KOMET stirring bars were specially
fitted with a wear-resistant glide ring for use under excruciating circumstances, such as
when stirring vessels feature rough plastic or stainless-steel bottoms or if the media to
be stirred contain solids (Figure 3).
Any risk of demagnetization by external magnetic fields is completely eliminated. All
KOMET series stirring bars can be readily recognized by their two conical ends.
