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ABC of Safety in the Biological Sciences
CENTRIFUGATION
Modern centrifuges must conform to certain standards.38 Centrifuges should be mounted on a stable base at a height that allows easy access to the bowl. Those using centrifuges need to pay particular attention to balancing, (pair buckets by weight), and proper containment of hazardous specimens during centrifugation. Commence centrifugation slowly.
A shield against rotor assembly failure should be provided. An interlocking system in modern centrifuges prevents initiation unless the lid is properly closed and access during centrifugation. Centrifuges without this safety feature should never be opened until the rotor has stopped.
A common design feature of centrifuges is the presence of holes which allow for air to enter and leave the chamber while the rotor is in motion. Units specially designed to operate in a closed system are required for handling pathogens. Flame proof motors are necessary in centrifuges operated where flammable materials are also in use.
Inspect the interior of centrifuge bowls regularly for any contamination. If a breakage occurs whilst the machine is in operation switch off and leave for 30 minutes to reduce the risk of aerosol contamination. If a breakage is discovered on opening the lid, close and leave for 30 minutes. Document the incident.
Wear strong, thick rubber gloves when cleaning a centrifuge. Use forceps and cotton swabs to pick up glass debris and place all broken glass and contaminated buckets, trunnions and so on in non-corrosive disinfectant (70% ethanol) for 24 hours. Swab the bowl with non-corrosive disinfectant, leave overnight and repeat. Treat all swabs as infected waste. Do not use hypochlorites as they are corrosive. Make sure that any centrifuges sent for repair have been safely decontaminated first. Rotor assemblies can be autoclaved or sterilised with ethylene oxide gas, formaldehyde gas, glutaraldehyde solution or ultra violet light.39
A safety zone of 300 mm is recommended around centrifuges. All staff should remain outside of this zone while a centrifuge rotor is in motion. Instruments designated as bench-top centrifuges should be used at floor level or should be contained by a barrier to prevent the unit vibrating off the edge of a bench. This also protects against rapid, hazardous movement after rotor failure.40 41
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