Failing to pull a vacuum with certain rotors

First and foremost, are you using the recommended Slo Accel mode for that particular rotor? In fact, ALL swinging buckets require the use of the Slo Accel mode on ALL Beckman centrifuges. This is because the rotors are very top heavy and the motion of the buckets as the rotor accelerates causes "precession" which makes the rotor wobble and in some cases like you are experiencing you get a bleeding away of the vacuum because the bellows seal between the drive assembly and the bottom plate is slightly breaking away at some point releasing the vacuum. This is hardly an uncommon problem that in many cases is rectified by what I just told you about the Slo Accel usage or in some cases it requires the cleaning and reapplication of high vacuum grease on the surfaces of the bellows assembly along with verifying the leveling of the centrifuge which can most definitely cause this problem too. At least those were some of the simple things that I discovered during my almost 33 year career with Beckman Coulter. Hope this helps. Don

Thanks for the reply - we're not changing the accel settings from default, but we are setting the rotor correctly, so presumably the machine uses the correct acceleration? We'll also try applying some vacuum grease at the bottom - any guide as to where exactly the grease goes would be much appreciated!

What are the "default" settings that you are using for the SW41 rotor? Unless there is a actual slow acceleration value showing up as opposed to just the normal acceleration rate of MAX then that really is the problem. You also should check the level of the centrifuge too because that too can cause problems with especially the SW rotors. As far as the vacuum grease application is concerned, that cannot be accomplished without the removal of the centrifuge drive itself so unless you have the necessary skills to do that then just forget about it unless you want to call for a field service engineer to show up. Don

By 'default' I meant that we program the correct rotor into the machine, then use it on max. Presumably if the rotor has certain acceleration requirements, Beckman will program that in to the settings when you choose that rotor? It would be odd if they didn't? We've also been using it on max accel for the past 20 years without issue! However if it is as simple as getting an engineer to replace the vacuum grease, that's a nice easy fix, thanks!

No, BCI did not do things that way because there were different profiles available for swinging bucket rotors that the customer can choose from depending on the type of separation the customer was doing. I worked on Beckman Ultracentrifuges for almost 33 years and ALL of my customers used an accel and decel profile for those types of rotors and never had any issues as long as they did. And getting an engineer in to drop the drive , check out the bellows, clean and regrease it is a very expensive proposition considering what their hourly rates for portal to portal travel and time on site are probably at right now unless you have a service agreement. Obviously your centrifuge to do as you please but checking the level on a rotor on the spindle is certainly an inexpensive option along with actually trying a profile other than max. Don

OK, got you. We do have the machines on contract for the yearly service but not for interim repairs, so we'll try the accel profile and if that doesn't fix it we'll hope the annual service is upcoming!