Before arriving at the details of centrifuge care, some paperwork must be done. First, there are manuals—your centrifuge came with one, and it includes a section on cleaning and maintenance, and quite possibly a list of chemicals/cleaners/disinfectants that are safe to use, and a list of those that are not. If the manual is missing, a duplicate is probably available online, and should be downloaded and printed. It is best to read it, and keep it handy, not only during initial runs but during the initial cleanings too. To come full circle, a maintenance log should be kept so that proper maintenance can be verified. This can be especially important in warranty claims.
Following a regular schedule will ensure that time is set aside and used for cleaning. (It is also often recommended to have staff assigned to this and other jobs.) While sometimes inconvenient, adhering to a regular program is cost-efficient and saves time in the long run.
For hazardous spills, your lab and/or institution will have a protocol that could include everything from kinds of protective gear and products, such as spill kits, to be used, to reporting and safety procedures. It is important that these are known and that they are followed. It is frequently the case that shortcuts, because they skip a step or detail, end up taking more time later. Know the kinds of samples being run in the lab; keep this information up to date, especially in a shared lab. This will help determine if any unique products or protocols are needed for cleaning. It is important to note as well that centrifuges can incorporate many materials, from stainless steel to carbon fiber to membrane switches and touch-sensitive display screens. The manual will be the best guide to the products and processes to use for cleaning each of these.
Centrifuge tips
- Always place the centrifuge on a flat surface first.
- Always unplug the power cord before cleaning.
- Emergency phone numbers and procedures should be posted and kept up to date.
- Wear disposable gloves.
- Follow your facility’s safety procedures when cleaning and disinfecting the centrifuge.
- Before moving the centrifuge to a new location, the exterior and interior surfaces should be cleaned and disinfected.
- Plug in centrifuge only when completely dry.
Cleaning
Centrifuge interiors are made from a range of materials—plastic, ceramic, aluminum and stainless steel—that manufacturers use in the search for performance in a high-stress environment. Manufacturers’ recommendations on the cleaners and scrubbers to use and method and frequency of application take this into account and will get the best results.
- Clean the centrifuge daily, or at least weekly.
- Remove the rotor and any sample or container holders.
- Interior cleaning includes the interior bucket, specimen holder, rotor and supports.
- Use a sponge, warm water and a mild detergent such as dishwashing liquid.
- Do not use caustic detergents or any product containing chlorine ions. (Diluted bleach is sometimes used as a disinfectant, but at full strength can attack stainless steel and discolor or damage the bowl (see below). A plastic scrub pad can be used, but products such as steel wool, wire brushes and other abrasives can damage coatings and lead to corrosion.
- Spills should be wiped up immediately.
- Clean both the exterior and the interior.
- Do not pour water directly into the chamber or flood the inside of the centrifuge with cleaner. Sensors, gaskets, seals, wiring and other parts that may be present can be easily damaged. Motors, vacuum pumps, condensers and other expensive parts can also be damaged by exposure to water and cleaning products.
- Scrub tube cavities with a test tube brush with nonmetallic tip. Dry each part with an absorbent towel.
Disinfecting and Decontamination
Disinfect on a regular basis. Approved disinfectants and/or “spill kits” should be used. A 10% bleach solution (one part bleach to nine parts water) can be used with some materials: consult manual. After cleaning with a bleach dilution, dispose of any remaining mix.
Many rotors have sealed compartments that provide aerosol containment and confine spills of toxic, pathogenic, infectious or radioactive materials. If breakage occurs, it may be that only the sealed containers require decontamination. It will be necessary to decontaminate the chamber if a sample-holder in an unsealed carrier breaks or if any occurrence allows the sample out of the sealed compartment. Allow sufficient time for the disinfectant to work. If a spill occurs outside a containment device, follow facility rules on procedures and reporting. The protocols for spills outside of containment devices, including centrifuges, almost always differ from those for contained spills, and users of equipment should be aware of the appropriate steps to promote worker and environmental safety. Spill clean-up requires proper personal protective equipment (PPE), including a lab coat or gown, and gloves. A face shield, shoe covers or respirator may be needed as well.
Spills of radioactive substances can often be addressed with a decontamination solution of 70% ethanol and 10% sodium dodecyl sulfate in water. Parts will need to be rinsed with ethanol first, and the following decontamination, with deionized water. Appropriate protective gear should be worn and properly disposed of after use.
Conclusion
Proper cleaning procedures, personal safety, and following regulations are critical to centrifuge use and maintenance. The larger goals are increasing unit durability and maintaining unit functionality, maximizing return on investment and having equipment that provides efficient, accurate and reliable performance. More information about centrifuge care and performance is available in “7 Questions to Optimize Centrifuge Performance,” a four-page document providing details on speed requirements, sample handling, operation, reliability and service and available from NuAire, Inc. at https://www.nuaire.com/sales-support/technical-papers/optimize-centrifuge-performance.php