How many revolutions are on that centrifuge?

Posted on by Mark

Customers purchasing a used centrifuge often ask the question,
“How many revolutions are on that centrifuge?”

The number of revolutions on the counter is an overall number of how much usage the entire centrifuge was used as a system. (Maybe)
The revolution counter is an electromechanical device that can fail and require replacement. This renders the overall counter number useless for assessing the total usage on the instrument.

Within that centrifuge are sub assemblies, such as the drive assembly, vacuum pumps refrigeration compressors. Each drive has a serial number, on a L8, L8M or Optima this could have been changed any number times, or it could be the original drive from the factory. Typically, there is a service card inside the instrument that the service engineer uses to log these drive changes as well as the revolutions on the counter at the time of a drive change. This is a much more accurate representation of the usage on the drive in the instrument. A seller should give you this information. The original log book is another source of useful information. These log books show how long the runs were and what type of rotors were used. The seller should provide this information for you if it is available. These questions are important if you are relying on the past usage an indicator of reliability. They are not important if the instrument has been rebuilt to original equipment standards, or truly is refurbished.

There are two refrigeration compressors in an L8 or L8M, (one for drive cooling and one for can cooling). These assemblies could also have been changed at any point in time.
To make a judgment or even a guess on how long this should last without putting gauges on the compressors and measuring its performance characteristics is just not possible.

The vacuum system consists of a mechanical rough pump and a diffusion pump.
The main vacuum pump is a mechanical device that has been manufactured with tight tolerances and requires periodic maintenance to continue working reliably.
Without seeing the service history no one can tell how long you can expect this unit to last. One tube leak during a sucrose gradient run that is not cleaned and flushed immediately will cause the pump to fail prematurely.
This is why Tritech always rebuilds our centrifuges before selling them. That is why we can offer a one year onsite warranty. There are plenty of instrument brokers that will sell you an instrument at a very low price. Make no mistake it is a gamble, you may win or you may loose, but you are gambling just the same. You should ask these questions of any company you are considering buying an instrument from?

Tritech is a service organization first and foremost. We know these instruments inside and out. We will be there long after the sale.

The Tritech purchase experience will make you a customer for life.