Centrifuges
Topics
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Principle of Operation
Diagrams
Applications
Types of Centrifuges
History
Safety
Operation
Preventive Maintenance
Common Failures
Basic Troubleshooting
Principle of Operation
 A centrifuge is a piece of equipment, generally driven
by an electric motor, that puts an object in rotation
around a fixed axis, applying a force perpendicular to the
axis to separate substances of different densities.
 Tubes in the centrifuge are tilted so centrifugal force
can pull denser substances towards the bottom of the
tube.
 Relative Centrifugal Force (RCF)
measures acceleration applied to
the sample
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RCF=(r*ω2)/g
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r=distance from center or motor to sample
ω= angular velocity (radians/ second)
g=9.8m/s2
Principle of Operation
Inputs
Outputs
AC Voltage
Rotating Rotor
Mixed Solution
Density Separated Layers
Diagrams
Rotor
Power
LED
Timer
Diagrams
Power
Source
Motor
Power
Distribution
Board
Timer
Safety
Switch
Power
Indicator
LED
Applications
 Separate solids from solution
 Used during urinalysis to separate disease identifying
components
 Separate blood into plasma and cellular components
Types of Centrifuges
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Centrifuges are generally divided into 3 categories based on
their maximum attainable speed:
1. "Low-speed": max ~5 x 103 rpm.
2. "High-speed": max ~2 x 104 rpm.
3. "Ultracentrifuges": max ~105 rpm
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Others
 Variable Temperatures
 Vacuum Capabilities
History
 English military engineer Benjamin Robins (1707-1751)
invented a whirling arm apparatus to determine drag.
 In 1864, Antonin Prandl invented the first dairy
centrifuge in order to separate cream from milk.
 In 1879, Gustaf de Laval demonstrated the first
continuous centrifugal separator, making its commercial
application feasible.
Safety
 Always use PPE.
 Before using, read the owner's manual.
 Do not operate a centrifuge until having been
shown proper use by an experienced operator.
 Check that the centrifuge chamber and drive
spindle of the rotor are free of scratches or
burrs.
 Decontaminate centrifuge of biological hazards
before servicing.
Safety
 Never repair a cracked or bent rotor.
 If rotor has been replaced, tighten knob/screw
fastening rotor to the shaft to prevent
hazardous loosening.
 Prolonged contact w/ some disinfectants can
cause damage to rotor and other components
(e.g. 10% sodium hypochlorite).
 Never attempt to touch or stop a spinning rotor
by hand or with another tool or object.
Operation
 Place tubes in centrifuge.
 Always use correct size tubes to prevent tube damage.
 Always using a counterbalance:
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By mass NOT volume
Put the tubes opposite each other in the centrifuge. If you
have more than two tubes, only the ones opposite each other
have to be equal in mass.
If centrifuge has variable speeds, enter RPM.
Close lid.
Turn timer on or press start.
Remove the tubes carefully after the centrifuge has
completely stopped spinning to prevent remixing.
Operation
 Result of unbalanced centrifuge
Preventive Maintenance
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Lubricate and clean motor.
Clean case.
Inspect power cords and plugs.
Inspect controls and switches.
Ensure appropriate menu settings for proper use.
Ensure tightness of rotor.
Check lights and indicators.
Verify that alarms are operating properly.
Ensure safety switch is functioning.
If refrigerated, ensure temperature reading is working.
Replace/repair gaskets, seals, and vacuum pump (if
applicable).
Common Failures
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Machine will not start.
Power supply is faulty.
Safety switch or timer not working properly.
Motor not working properly.
Motor making noise.
Rotor is broken.
Lid will not open or close.
Basic Troubleshooting
 See flow chart.