3 Operation
3.1 Rotor
and
Accessories
A balanced load
is essential for all centrifuges. An
unbalanced load produces vibration, and can damage the
unit. A 2 gram load imbalance, at a speed of 4600 RPM,
imparts force equivalent to 9.1 kg (20 pounds) at rest.
Always ensure that the rotor is loaded symmetrically, with
a full complement of accessories, and a full (or paired) set
of tubes. Tube adapters should also be installed
symmetrically.
The rotors are dynamically balanced at the factory. The
manufacturer matches removable parts (trunnion rings,
shields, buckets, and carriers) to within 1 gram, and stamps
the weight on each piece. Check these markings, whenever
you interchange parts, to ensure that opposite parts are
matched. Ensure that the total weight of samples and
removable parts, loaded in opposing positions, are equal in
weight, to within 1 gram. The position numbers, present on
many rotors and adapters, identify opposing tube positions.
To obtain good dynamic balance, opposite loads must not
only be equal in mass, but must, also, have the same
centers of gravity. Opposing containers must be alike in
shape, thickness, and distribution of glass or plastic. This
is especially important for large containers.
MARATHON Series Operation Manual
15
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