Centrifuge

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• Centrifuge
• Safety

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Warning

• Basically very simple
• Potentially very dangerous

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An example of an accident
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• Large aluminium rotor in Beckman L2-65B
• Rotor failed one hour into the run.
• The safety shielding of the unit did not
  contain all the metal fragments.
• The 14 mm thick sliding steel door on top of the
  unit buckled, allowing the steel rotor top to
  escape plus other metal fragments.

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• The unit itself was propelled sideways and
  damaged cabinets and shelving that contained over
  a hundred chemicals.
• Fragments from the accident made holes in the
  wall ceiling ruined a nearby fridge and
  ultra-low temperature freezer
• A shock wave from the accident shattered all
  four windows in the room and shook the wall
  causing shelving to collapse.

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Centrifuges Possess a Lot of Energy

• Friction with air causes heating thus faster
  machines need to run with a vacuum.
• High speed and ultra-centrifuges also need
  refrigeration to preserve the samples

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Rotor Life

• Rotors are subjected to extreme forces.
• Rotor life is dependent on the number of hours of
  spinning.
• Rotor life is also dependent on the care used to
  preserve the integrity of the tube holders.
• Therefore we must log all run parameters

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Run parameters

• Date.
• Operator
• Rpm (speed) required.
• Run time required
• Rotor type to be used

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Speeds

• Low to Medium - up to 10,000 rpm
• High Speed up to 21,000 rpm
• Ultraspeed up to 90,000 rpm or more

Overspeed dial prevents running rotor too fast
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Low to Medium Speed

• No vacuum required
• May be refrigerated
• Tubes (and rotors) must be well balanced.

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High Speed

• Must be refrigerated
• Must be at least partially evacuated
• Tubes must be very well balanced

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Ultraspeed

• Must be refrigerated
• Must be evacuated
• Tubes must be extremely well balanced
• better than 10 mg

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Rotor Types

• Swinging Bucket
• Low Speed
• Ultraspeed
• Need very special attention

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Rotor Types

• Angled
• Angled
• Vertical

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Theory

• RCF 1.12r (N)2
• RCF relative centrifuge force (g)
• r radius in mm
• (N rpm in 1000s)
• Usually use a nomogram to calculate

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rpm
Radius (mm)
g
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Theory

• Sedimentation Coefficient
• A measure of the particle being sedimented.
• Measured in Svedberg units S
• Primarily density related but also related to
  size.
• Clearing Factor K
• A measure of the sedimenting ability of the rotor.

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General Safety

• Maximum speed
• Securing rotor
• Balancing rotor
• Selecting correct tubes
• Correct filling of tubes
• (do not overfill)
• Flammables

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Bio Safety

• Biocontainment
• Decontamination

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Loading

• Balancing of tubes
• Symmetrical arrangement
• Load about the centre
• No overfilled tubes

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Load about the centre
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Load symmetrically
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Rotor Washing

• Use mild detergent and soft brush. DO NOT
  SCRATCH SURFACE WITH WIRE BRUSH
• Rinse with distilled water
• Leave rotor inverted on towel to drain

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Poor Rotor Housekeeping
Pitting, corrosion and salt deposits shown
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Centrifuge Maintenance

• Wipe centrifuge bowl with damp cloth to remove
  salts and dirt
• Clean lightly grease centrifuge lid seal
• Clean rotor lid and lightly grease o-ring
• Check for scratches and pitting in the rotor
  tube holders

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Summary

• There is the potential for serious accidents
  with the misuse of any centrifuge
• Take care in all aspects of use with particular
  attention to balancing of tubes and proper
  cleaning of the rotors
• Report any damage of a rotor.