Centrifuges are an important part of research equipment and operate very fast. The high operating speed of the centrifuge is beneficial as it allows separation of materials based on density. The speed at which the centrifuge operates can present hazards ranging from aerosol production to equipment instability and failure. Aerosols can be generated when centrifuge tubes or sample tubes break inside the rotor. Additionally, an unbalanced rotor can create instability inside the device. This greatly increases the operating speed of the centrifuge. and may result in injury to the user or damage to the laboratory.
In an article written by the Laboratory Safety Committee of the American Industrial Hygiene Association (AIHA), AIHA described an incident in which an ultracentrifuge malfunctioned while in use. According to the article, “The rotors inside the ultracentrifuge fail due to excessive mechanical stress caused by high rotational speeds”. When the rotor failed, flying metal fragments were released from the centrifuge, damaging walls, ceilings and other nearby lab equipment. Equipment failure was due to the use of rotors not approved for use by the manufacturer. Researchers must follow the manufacturer’s operating instructions for the make and model of centrifuge used in the laboratory.
History:
Beckman Instruments Emergency Corrective Action Notice (Adobe Acrobat format), dated June 22, 1984, describing two centrifuge accidents similar to the Cornell accident. The letter goes on to explain that operators of Beckman centrifuges must only use the specific types of rotors that Beckman has approved for each specific model of centrifuge. This letter provides a complete list of approved rotors for all L, L2, L3, and L4 centrifuges. NOTE: Although this letter was sent to the owner of the Beckman centrifuge 15 years ago. But this information still applies to these models. It is important that operators of these devices follow these guidelines.
The Beckman Coulter Rotor Safety Guide (Adobe Acrobat format), which explains why a rotor can fail, how to minimize the risk of rotor failure, and the rotor warranty.
The Sorvall Rotor Care Guide explains how to care for and prevent rotor damage, how to inspect rotors for damage, and rotor warranty. (Note: This is an Adobe Acrobat file larger than 10 MB.)
The campus laboratory was severely damaged when the rotor of the ultracentrifuge failed in use. Flying metal fragments damaged walls, ceilings and other equipment. The shock wave blew out the lab windows and shook the shelves.
Description of accident
On December 16, 1998, milk samples were run in a Beckman.L2-65B ultracentrifuge using a large aluminum rotor (a rotor is a large metal object that holds a single sample tube and connects to the centrifuge’s rotating drive). This rotor has been used for this procedure many times before. After about an hour of operation, the rotor failed due to excessive mechanical stress caused by the “G” force at high rpm. The subsequent explosion completely destroyed the centrifuge (Figure 1) (Figure 2).
The safety shield in the unit did not contain all the metal fragments. A half-inch-thick sliding steel door on the top of the unit snaps to allow debris, including the top of the steel rotor, to escape (picture3). In addition to punching holes in walls and ceilings, the debris damaged nearby refrigerators and ultra-cold freezers. The unit itself was propelled sideways, damaging cabinets and shelves (pictures4) containing more than a hundred chemical containers. Fortunately, sliding cabinet doors prevent containers from falling to the floor and breaking. The shock wave from the accident shattered all four windows in the room. The shock wave also damaged the incubator’s control system and shook the interior walls, causing shelves on the wall to collapse (picture5). Fortunately, the room was unoccupied at the time and no one was injured.
The cause of the accident is believed to be the use of a rotor model not approved by Beckman for use in the Model L2-65B ultracentrifuge.
Prevent centrifuge accidents
Rotors on high-speed centrifuges and ultracentrifuges are subjected to strong mechanical stress that can lead to rotor failure. Additionally, improperly loaded and balanced rotors can cause the rotors to loosen as they spin. Everyone using this type of equipment needs to know the proper operating procedures for the specific equipment being run, including how to select, load, balance and clean rotors. These procedures are described in the equipment’s operating manual.
Some rotors will also need to be “downgraded” based on the amount of usage the rotor has received (limiting the maximum speed of the used rotor to some level below the maximum speed listed for the new rotor). This requires the operator to maintain a comprehensive usage log for each rotor. These procedures are described in the operating manual.
Laboratory supervisors must ensure that operators of such equipment are properly trained in rotor selection, maintenance, and use. If a trained and experienced operator is unable to train a new operator, contact the service representative for the equipment and schedule a training program. Check out the contact list below for details. If you are unable to contact the manufacturer, please contact REM Industrial Hygiene and Laboratory Safety.
In the event of operational problems with the high-speed centrifuge or ultracentrifuge, or if the rotors show signs of wear or damage, the equipment should be taken out of service immediately and clearly marked “WARNING – DO NOT USE” until inspected by an authorized service representative. Check the included contact list.
Centrifuge accidents can be prevented when users choose to operate high-speed centrifuges and ultracentrifuges safely. The following will provide tips to reduce the likelihood of a centrifuge accident or injury:
- Make sure the centrifuge bowl and centrifuge tubes are dry
- Use matching tubes, buckets and other equipment
- Inspect tubes, sample containers, and sample tube tops for cracks, rips, or other damage before use
- Always use centrifuge safety cups with aerosol lids to contain spills and prevent aerosols of potentially infectious materials
- If infectious material is spilled, wait 10 minutes after the rotor has stopped before opening the lid
- Avoid overfilling the tube or container – centrifugal force may push the solution up the sides of the tube or container wall
- Make sure the rotor is properly and securely mounted on the rotating drive or drive shaft
- O-rings should only be inspected with proper training
- Do not exceed the maximum operating speed of the rotor
- Make sure the centrifuge is functioning properly before leaving the area
- Make sure the rotor comes to a complete stop before opening the lid
- Close the centrifuge lid during a run
- Decontaminate centrifuge with 70% ethanol or 10% bleach solution after spill
- Schedule regular preventive maintenance
Special Hazard Warnings for Old Equipment
Older devices don’t have all the security features built into newer devices. They are more likely to experience rotor failures and are more likely to cause injury in the event of a failure. It is important to follow all safety and maintenance procedures specified by the manufacturer. Based on the investigation of the December 16, 1998 Cornell accident, it was learned that Beckman L2 and L3 series ultracentrifuges have special operating procedures and restrictions to reduce the risk of damage and injury. This includes orange decals on the sliding doors specifying which rotor models are safe to use in a particular unit (picture).
Refer To：Centrifuge Explosion