Really RCF is what matters, not rpm’s. You need to take into consideration the diameter of your rotor.
example:
One of the centrifuge we have has a 15.6cm radius rotor, at 6krpm that gives you 6240 RCF.
That is alot of energy, if not properly balanced it can cause stress cracking in your rotor. In addition high speed rotors are only good for a certain # of hours before they need to be replaced. Please balance your load with care, and examine the rotor before use. With refrigerated centrifuges make sure to wipe up any ice/condensed h20 after your done and leave the lid open so it can dry. Ice/ water can cause major imbalance issues.
https://www.chem.purdue.edu/chemsafety/news-and-stories/CentrifugeDamages.html
there is a lot of energy in a centrifuge, treat it with respect.