Centrifuge Sins

What are seven of  the most common mistakes made by customers and distributors when ordering a centrifuge for your laboratory?

 


Introduction


 

The lab item that often causes buyer remorse is a centrifuge.  Hopefully, the info in this blog post can help you can avoid some of these mistakes on your next purchase!

If you new to centrifugation or would like a review  this is  a great article by Beckman Coulter Life Sciences that will help bring you up to speed.

 


Do you buy new or used?


If you are starting up a new lab on a tight budget, it doesn’t take a lot of searching to find a number of used centrifuges for sale on sites like eBay or LabX.

Reasons TO buy used:

  • Previous lab experience with a specific model centrifuge.
  • Currently you own  the EXACT same unit so you already have all of the rotors, carriers and components that the used unit will require.
  • The manufacturer still field services and (this is important) still stocks parts.  Make sure the obsolescence date is at least a few years in the future.
  • You have the ability and time and money to clean and prepare the unit to prepare it for routine use.  Many used units sit in some very sketchy conditions and it’s not uncommon to find various animal homes inside.

Reasons avoid used: units:

  • The manufacturer no longer services or has repair parts for the unit.
  • An “as is, no refunds” clause.
  • The return shipping charges are the buyersresponsibility if the unit is defective.
  • The total price including accessories you may have to buy is within 25% of the price of a new unit.
  • No warranty.

Refrigerated or Non-Refrigerated?


 There really is no downside to buying a refrigerated version other than the price and maybe the footprint.  If you don’t care if some samples spin hot (and they will if you don’t have a refrigerated unit!) and you will never in the estimated 10 – 15 year life expectancy of the centrifuge ever have temperature sensitive samples then don’t buy a refrigerated unit.

There are not a lot of used non-refrigerated units for sale.  There is a reason for that.


For a specific task or for general use?


 So you are ramping up for a new test and you really need to spin micro or PCR plates.  There are plenty of centrifuges out there specifically designed for that single task.  There are a lot of other centrifuges which have rotors that will take adapters that will do the task.  Do you shoot for a unit that you can be used for other things later or go with one that is dedicated to this task?

If the centrifuge will be shared among several labs, deciding on the right unit this takes careful consideration among all the parties.

Many centrifuges are capable of using  different types of rotors.  Rotors are often heavy and hard to pull off the spindle.  Smaller lab workers may not even be able to lift them!   In many cases one rotor is all that is ever used and other rotors initially purchased collect dust.

Expensive high performance floor model centrifuges that use fixed angle rotors typically have an assortment of rotors sitting around and are better designed to make the process easier.  There are 3rd party rotor makers who construct lighter weight rotors using carbon fiber materials.  These are much easier to lift and cause a lot less back strain.


The hidden cost of choosing the wrong voltage!


 The larger the centrifuge, the more electric energy it takes to start and stop (centrifuge breaks are electrical, not mechanical.  Many buyers purchase 115V units that have amperage requirements that far exceed their circuit capacity. This is why many centrifuges come with 208V or 220V requirements.

 Many newer labs have lots of 120V plugs and some may even come with 220V plugs for things like washers and large refrigerators.  But how many labs come with plugs for 208V?

Here is an explanation of the difference:

The difference between 208V three phase, and 240V single phase, is how the voltage is derived.

240V single phase is obtained by taking a single leg of three-phase power.
208V three phase is obtained by taking two legs of three-phase power.

In a 120/240 single phase system, the midpoint of the secondary side of the tranformer is tapped and grounded to create a neutral. From the midpoint to any line reads 120V, and from line-to-line (the full voltage) reads 240V.

If your head is spinning, imagine how you will feel when you get your new refrigerated centrifuge and then have to explain this to an electrician!  Gear up because a lot of centrifuges are wired for 208V three phase and if you buy one you will need to plug it into the right receptacle!


Floor model or bench top?


Over the years, there have been many debates over this topic.  We won’t settle thas debate here; I’m just going to point out some things you should keep in mind before committing one way or the other:

  • - Floor models typically cost more and require a lot more electricity.  Is there a space to put it next to the work area?
  • - Bench models take up more workspace that is often at a premium.
  • - For the many routine tasks, a bench model will do the job as well as a floor model.
  • - If you have a lot of samples, you can probably configure a floor model to hold more than the highest capacity bench top.  But with the price difference, you may be able to get two bench tops for the price of a single floor model.
  • - A floor model centrifuge may require preventative maintenance and a service contract.
  • - You are going to walk further to get samples to and from a floor model than you would a bench top.

Brand name or a brand you don’t recognize?


It wasn’t that long ago that the choice of centrifuge brands was quite limited:

  • - Beckman Coulter

  • - Sorvall (later purchased by Thermo)

  • - Eppendorf

There were others, but these were the models with the most familiar names.  Today, that list is much longer (see Lab Manager’s list here which is far from complete.)  Lab Manager also offers a free resource guide for centrifuges available here.

So what is the price difference between a name brand product and a less familiar name?

Eppendorf Model 5418 Refrigerated Microcentrifuge, P/N 5401000137 – Retail Price $7,251.06

Hermle Model  Z216-MK Refrigerated Microcentrifuge, P/N Z216-2420H – Retail Price $6,558.91.

Price difference:  9.5% ($692.15.)  All other specifications are essentially equal.  The rotor is bundled on the Eppendorf and is sold separately on the Hermle (included in this example.)  Both units are manufactured in Germany.  These are LIST price comparisons and don’t include discounts.

Is an Eppendorf product worth the added $700 (or more) additional cost?   In my experience, when the price difference is this close, lab managers will almost always go with the brand name.


Will the centrifuge handle your samples and sample volume?


This is one area where logical thinking often isn’t applied.  For example, if you could buy one centrifuge that would spin all of your samples at one time in one run, but you could be two smaller centrifuges for the same or less to handle the same capacity, which would you choose?

The price you pay for a centrifuge is largely governed by the number of samples it will spin at one time and whether or not it is refrigerated.  People often estimate their needs based on the heaviest workload they have ever encountered.  Wouldn’t it make more sense to base it on a typical workload and projected rate of growth?  If your workload goes up that much, so will your revenue stream and you will easily be able to justify the purchase of additional units.


Summary


Realize that companies who sell these products do this full time and deal with sizing and configuration issues every day.  They are really worth listening to before you cut a purchase order!

There are many new brands of highly reliable centrifuges on the market today.  The capability of building a good centrifuge is no longer in the hands of a few companies.  There are many more choices today.  It’s really worth the time to shop around!

Buying the wrong thing or in a configuration that won’t spin your samples can be a costly and frustrating mistake!  Don’t let it happen to you.

 

 

Benchmark-Centrifuge-Selections