Ultracentrifuges are specialized pieces of laboratory equipment, designed to spin samples at speeds of up to 150,000 rpm (>1,000,000 x g). They enable the separation of particles such as viruses, organelles, multi-protein complexes, and plasmid DNA—all of which are too small to be isolated using a conventional centrifuge. Because ultracentrifuges operate at such high speeds, it is critical that personnel are trained in using them correctly and that regular preventative maintenance is carried out. It is also essential that an ultracentrifuge service contract be put in place to cover installation, routine inspection, and any necessary repairs. Failure to take proper care of ultracentrifuges can lead to disaster – as exemplified by a well-documented ultracentrifuge explosion, often mentioned as something to be avoided when introducing new end users to the lab.
Ultracentrifuges have the potential to cause serious harm
Unlike most large pieces of shared laboratory equipment, ultracentrifuges have the potential to cause serious harm—or even death—if they are not treated with respect. Many researchers are familiar with the 1998 incident at Cornell University, where misuse of an ultracentrifuge led to a laboratory being badly damaged when the rotor failed during operation. The resulting explosion, which occurred approximately one hour into the run-time, completely destroyed the ultracentrifuge and a nearby ultralow temperature freezer. It also damaged shelving used to store chemicals, shattered all of the laboratory windows, and created holes in the walls and ceiling. Thankfully, no personnel were in the vicinity of the ultracentrifuge at the time. During the subsequent investigation, the accident was found most likely to have been caused by an incorrect rotor being paired with the ultracentrifuge in question, highlighting the need to exercise extreme caution when working with these formidable pieces of kit.
Designed with protection in mind
When purchasing an ultracentrifuge, there are several important safety features that are worth looking out for. One such example is the presence of non-contact imbalance detection sensors that can pick up major vibrations and stop the ultracentrifuge from running where its operation has unexpectedly become unsafe. Another is the inclusion of self-locking rotors that eliminate the need to use tools for attaching the rotor to the drive shaft, thereby reducing the risk of operator error; in these systems, the centrifugal force generated as the machine starts up automatically locks the rotor into place. Where an ultracentrifuge is fitted with an automatic rotor life management (RLM) system, this removes the need to manually record rotor operation in a logbook and ensures metal rotors do not exceed their useable lifespan. Additionally, most modern ultracentrifuges include touchscreen controls that can be configured to require an operator ID be entered prior to use; digital keypads also play a vital role in making sure run information is input correctly.
Safe operation begins with installation
One of the first steps toward ensuring an ultracentrifuge performs safely is having it installed by a qualified engineer—not doing this will invalidate any instrument warranty, as well as putting end users and other laboratory personnel at significant risk. During installation, the ultracentrifuge should be fitted to an appropriate power source, provided with sufficient clearance on all sides, and should then be carefully leveled. If, at a later date, it is decided that the ultracentrifuge needs to be moved to a different location, a trained service engineer should be brought in to reinstall and relevel it once it reaches the new site.
Preventative maintenance is essential
Like any piece of laboratory equipment that will be shared by multiple end users, ultracentrifuges require regular preventative maintenance to guarantee their safe performance. Both before and after each use, the instrument chamber, rotor, and rotor lid should be inspected for scratches, corrosion, dust, or spilled liquids—including the underside of the rotor and the inside of tube bores. If any contaminants are found during this process, they should be removed according to the manufacturer’s instructions. (It is important to note that the choice of cleaning solution can vary according to the material the ultracentrifuge is made of; in all cases, abrasive cleaning products such as steel wool or wire brushes should be avoided since these can damage the instrument and impact its safe function). Good practice guidelines suggest wiping down the housing and the ultracentrifuge chamber frequently, along with the rotor and drive shaft, and lubricating any metal threads or O-rings after cleaning has taken place. When the ultracentrifuge is not in use, the lid should be left ajar to minimize pressure on the spring lifts. Leaving the lid in a slightly open position will also help prevent condensation from building up in refrigerated models.
An ultracentrifuge service contract offers many benefits
To ensure an ultracentrifuge continues to perform both safely and efficiently, it is vital that a service contract be put in place. A typical ultracentrifuge service agreement includes an annual visit from a qualified service engineer to check that the instrument, rotor, and any accessories are in good condition; in many cases it also covers the cost of certain repairs. Factors to consider when selecting a suitable service level include the length of downtime that will be involved during the annual inspection, as well as the expected turnaround time for any repairs. Where the ultracentrifuge will be subject to heavy use, more frequent inspection (e.g. a biannual service visit) may be deemed appropriate. In this situation, it can especially be sensible to find out how many service engineers cover the territory and whether they are located nearby. Other key considerations include establishing whether there is a limit to the number of call outs, or the cost of any replacement parts, and determining whether the service agreement covers any instrument upgrades that may become available after purchase.