TTUHSC hosts Lunch and Learn on Centrifuge and Rotor Safety in November

by Renee Witherspoon, MS, CSP, CIH, CHMM, Occupational Safety Manager at TTUHSC and ASSE South Plains Chapter Past President (2012-2015)

Rob Brown with Thermo Fisher demonstrates how rotors can become damaged at a recent Lunch and Learn.

On November 8, 2017 TTUHSC Department of Safety Services hosted Rob Brown at a Lunch-and-Learn event on Centrifuge and Rotor Safety.  Rob is a Centrifuge Product Specialist at Thermo Fisher Scientific in Houston. ASSE South Plains Chapter member, Brandon Mount, MS, CSP, TTUHSC Laboratory Safety Manager and Kate McKee, MS, Territory Sales Representative at Thermo Fisher Scientific, organized the event.

Laboratory centrifuges and rotors operate at high speeds and create strong centripetal forces. (For a small fixed angle 6×180 microliter rotor running at 110,000 RPM, that is equivalent to about 199,000 g’s!)  Because of these high speeds there is a potential for causing serious injury or death if these are not operated in accordance with manufacturers recommendations.

At the Lunch-and-Learn event Rob presented an overview of centrifugation and centrifuge and rotor safety.  He finished up with a Q&A session and a quick show-and-tell on three rotors identified during a laboratory inspection conducted prior to the event. The following is a link to his presentation: Rotor Safety Presentation

The laboratory inspection process was very helpful as it provided:

  • Walkthrough with the Safety team in key lab areas inspecting available centrifuges and rotors using non-destructive techniques. Note: If the rotor was not tagged “out of service,” the inspection team assumed that it could be used and included it in the inspection process.
  • Discussion with lab personnel on safety, possible repairs, care and handling from a trained expert in the field.
  • Recommendations on rotor retirement based on condition, run cycles or age. Follow-up by a written report of findings.
  • Demo’s for the Lunch-and-Learn presentation so that attendees could see real-life examples of rotors and rotor damage.

Although centrifuges are designed to contain the rotor in the event of a failure, there have been documented failures that have caused injuries prompting the lab safety team to prioritize centrifuge safety and look for areas of improvement.

According to OSHA a majority of all centrifuge accidents result from user error. Failure of a rotor can result in the release of flying objects, hazardous chemicals, and biohazardous materials.

Some of the common user errors include:

  • Failure to properly place and secure the rotor lid.
  • Failure to properly secure the rotor to the drive shaft of the centrifuge.
  • Overloading the rotor’s maximum mass.
  • Running swinging bucket rotor with missing buckets.
  • Hooking buckets incorrectly so that they cannot swing freely.
  • Improper balancing of centrifuge tubes.
  • Utilization of centrifuge tubes that are not rated for the correct speed.

Key to minimize accidents in user errors is to make sure that all laboratory personnel are trained on “symmetry” when loading there samples.  Essentially the mass (tubes/containers) have to balance each other so that the rotor on the shaft has no torque that could imbalance the load.  Critical is that samples have to be directly across from each other when loading the rotor and doing a centrifuge run.  This is particularly important for the ultracentrifuge.  A recommendation from ASU.edu states that each mass should be within 0.03 grams for ultracentrifuge runs.

Centrifuges are divided into types based on their rotor design: fixed angle, swinging bucket and continuous flow. Most of the rotors the lab safety team inspected were older so there

Example of corrosion and pitting in a rotor.

were a few that had lost their finish and have telltale signs of damage including development of pitting and corrosion in the cavities or on the surface of the rotor. Others showed wear of the pins where it appeared that the rotor had been dropped into the centrifuge, and have damaged the pins.  With some of the older rotors weighing over 50 pounds, it is understandable that damage was found.  Considerable advances in carbon fiber have significantly decreased weights and the possibility of back injury.  Also identified were ultracentrifuge rotors with missing or damaged overspeed disks.  Missing overspeed disks mean that the speed control frequency may be exceeded, damaging the rotor.

Below is a table Rob provided on recommended rotor life.  He states, “…these are general guidelines and rotors can age with grace or prematurely, so real rotor lives may vary.”  He also warned that we need to, “Keep in mind that Titanium is a strong yet brittle metal and rarely shows signs of ware or fatigue before an accident happens.”

What I came away with as part of the lab safety team, was not only the importance of establishing a regular rotor maintenance program, but a lesson learned: how improper cleaning can significantly impact the life of a rotor.  And the importance of using a logbook to help track rotor and instrument usage patterns.

Overall the experience of getting in an outside expert like Rob to inspect our centrifuges was invaluable.  He assisted us in identifying potential problem areas, that now we can not only correct them, but can improve our lab safety program. Another benefit by conducting the inspection and follow-up training in a Lunch-and-Learn we were able to increase awareness on centrifuge safety. A definite win-win for the lab safety team and the biomedical researchers using centrifugation.

What will we do with the rotors that were tagged “out of service” during the inspection process?

We are looking at an exchange program with the manufacturer to purchase new rotors, so don’t recycle them as scrap metal. If you have other questions, you are welcome to email me at: renee.witherspoon@ttuhsc.edu

References: Goodman, T. “Centrifuge Rotor Selection and Maintenance” Thermo Fisher Scientific Inc., 2007; OSHA Quick Facts, “Laboratory Safety Centrifuges

*A big thanks to Thermo Scientific, Rob and Kate for sponsoring lunch and for raising awareness on the importance of centrifuge safety.  Thank you for all of your time and efforts in promoting safety excellence for laboratory researchers. 

To contact Rob Brown at ThermoFisher and set up an inspection for your facility, email him at: rob.brown@thermofisher.com, or call at 346-212-4402.  Contact Kate McKee, Territory Sales Rep for Thermo Fisher Scientific here in Lubbock area (she also does Amarillo, Oklahoma & Arkansas) at kate.mckee@thermofisher.com

Don’t be surprised what you’ll find when you start looking! Example of an old swinging bucket rotor where the trunnion has been repaired with a little “Bondo.”