With OSHA reporting that the majority of centrifuge accidents occur as a result of user error, it’s clear that centrifuge misuse poses a considerable safety risk. The issue is compounded by the fact that centrifuges are typically a shared laboratory resource, highlighting the importance of user accountability and the need to adopt best practices for safety. To better understand how to avoid accidents as a result of incorrect use and to maximize centrifuge performance, we spoke with Matt Squire, product engineer, and Ryan Rostowski, regional sales manager, at NuAire, Inc. They suggested some simple activities that are easily incorporated into daily routines.
“It should never be assumed that integral parts such as the rotor or buckets can be switched interchangeably between one centrifuge and another,” reports Squire. “For any centrifuge to operate effectively, the correct internal components must be used. An incompatible rotor can cause the centrifuge to vibrate, resulting in lost samples, damage to the instrument, and potential harm to end users.”
“Checking that the rotor is locked into place takes just seconds, but it is a critical step in ensuring centrifuge performance and safety,” notes Rostowski. “Historically, a hand tool was required to set a rotor on the drive shaft. With new technology it is possible to achieve this automatically, but although automatic locking greatly reduces the chances of a malfunction, it is still good practice to try gently lifting a rotor after installation to confirm it is secure.”
A swinging bucket rotor is the most common rotor type and, according to Squire, should always be loaded with all its buckets for optimal centrifuge performance. “Using the full complement of buckets helps to balance the load,” he says. “If the buckets contain inserts, a quick visual check to ensure each of these is in place before starting the run can prevent a malfunction due to uneven weight. Where biocontainment lids are required, it is important to confirm these are firmly locked in position.”
To minimize the risk of sample leakage due to tubes breaking under centrifugal force, it is essential that appropriate bucket inserts are chosen. “A tube with a round base should never be used in an insert designed for a tube with a conical base, since in this situation the tube will not be properly supported,” explains Rostowski. “Likewise, each tube should be of the correct diameter to fit the insert snugly and should have the proper g-force rating for the protocol in which it is being used.”
“Every researcher knows that effective centrifugation hinges on a properly balanced load, and the best way of achieving this is to balance samples according to weight,” says Squire. “Researchers should also check tubes thoroughly for cracks or flaws before using them and should never exceed the recommended fill height. Leaking tubes can result in an imbalance and may also cause the centrifuge to become contaminated.”
When using a refrigerated centrifuge, it is important to run a pre-cool cycle before the first sample run to cool the bowl, rotor, and buckets down to the setpoint (usually 4°C). Then, when running samples, the centrifuge will only have to maintain this temperature throughout the run. “This approach will provide more consistent results since the centrifuge is starting the run at sample temperature rather than room temperature,” explains Squire.
“Once you’ve loaded the centrifuge, you should always make sure it is functioning normally before you walk away,” says Squire. “The acceleration period is the best time to identify and resolve any issues, and the time spent waiting for the centrifuge to reach full speed is negligible compared to the days of lost service that can result from the instrument breaking down.”
It is common courtesy to leave the centrifuge in the same condition you would expect to find it. This includes returning bucket inserts if they have been used to transport samples across the laboratory, removing balance tubes, and decontaminating any spills that may have occurred. “Unless consecutive refrigerated cycles will be carried out during the day, the centrifuge lid should be left open to prevent condensation pooling in the bottom of the centrifuge bowl,” notes Rostowski. “Not only does liquid harbor the growth of microorganisms, it can also negatively affect centrifuge performance. Moreover, it is good practice to remove the rotor at the end of each day so that this too has a chance to dry out.”
To learn more about caring for your centrifuge from the experts at NuAire, please visit www.nuaire.com