Talk:Centrifuge

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Technology

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mistake in the description[edit]

Both light and heavy particles experience the same centrifugal acceleration and move out radically (towards the bottom of the tube). If there were no friction, both would reach the bottom together (Galileo's famous feather and coin experiment). However, because of the Stokes's friction, which depends on the size, larger and heavier particle moves faster. This is useful in the lab for fractional or partial sedimentation where larger particles (e.g., cell organelles) are sedimented but small particles (e.g., proteins and nucleic acids) stay back in solution.

It is wrong to state that lighter or smaller particles will float up to the top. They can float up only if the buoyancy effects cause the effective mass to be negative. Ck.mitra (talk) 13:51, 5 January 2010 (UTC)[reply]

History of the centrifuge[edit]

The name Antonin Prandl should be spelled Antonin Prandtl. Moreover, according to this source he merely adapted an already existing centrifuge used for sugar (crystal/syrup) separation. I don't know how reliable that source is, but I do believe that centrifuges had been in use since the end of the 1700s. See for instance the invention of the tumble dryer in 1799. Can anyone access this article (and read it, as it's in German)? It might give some more clues on the Prandtl story... Lvzon (talk) 01:03, 15 September 2008 (UTC)[reply]

Some discussion of where centrifugal force comes from?

The discussion on where the centrifugal force comes from could be a little complicated since it isn't a real force.

There already exists an article on centrifugal force, and see Sedimentation for the explanation of the process in a centrifuge. Moreover, the fact that centrifugal force isn't a real force in the Newtonian sense is irrelevant here, as it's very real to the particles experiencing it... (or the goldfish, see below ;) Lvzon (talk) 01:03, 15 September 2008 (UTC)[reply]

?? Why the centrifugal force is not a real force? How did you arrive at this conclusion? It is a force in all practical sense.

I can guess the origin of this confusion. A rotating frame is not an inertial frame and therefore contains forces. There is noting "virtual" about these forces.Ck.mitra (talk) 19:11, 29 June 2009 (UTC)[reply]

What is the highest acceleration of a centrifuge?[edit]

It would be nice to include this piece of info. What are the uber-centribuge, who makes/made them, where were/are they used?

One link: A special 750 Gs centrifuge able to handle test items weighing up to 250 pounds is believed to possess the highest such capability in the nation. http://www.ntscorp.com/services/service_detail.php?id=189

I'm not sure what the fastest centrifuge is, but current ultracentrifuges can do 150,000 RPM and generate around 1,000,000 g. Lvzon (talk) 01:03, 15 September 2008 (UTC)[reply]

I am not sure there is a commercial ultracentrifuge today that can do 150,000 RPM. However, most common ultra's can go upto 80,000 g.Ck.mitra (talk) 13:37, 5 January 2010 (UTC)[reply]

What is RCF (Relative Centrifugal Force)? "Minimum RCF is 13,400 g ([1])"

RCF is the amount of centrifugal acceleration relative to the average gravitational acceleration of 9.81 m*s^-2. Lvzon (talk) 01:03, 15 September 2008 (UTC)[reply]

what would happen if a goldfish were centrifuged? Would it separate the liquid in the fish from the solid?

depends on how hard you centrifuge it :) Jaeger5432 15:38, 18 August 2006 (UTC)[reply]

To add to an above question, what is RCF mesaured in? Gees?

RCF is a ratio of two forces and has no units. Often however, people loosely refer the centrifugal force as 70,000g (meaning that the RCF is 70,000)Ck.mitra (talk) 19:17, 29 June 2009 (UTC)[reply]

Apparently it is measured in g's. Technically, there is no such thing as "centrifugal force". I don't remember everything my college physics professor explained, but the relative force associated centrifugally has to do with one's inertia. Gees probably would be the best way to measure the force, as I mention below about the purification of oils, it is compared to gravity separation, so a comparison in gees makes the most sense. Hengineer 07:58, 25 April 2007 (UTC)[reply]

uses[edit]

Dairy cream separator used a centrefuge.. -- Librarianofages 04:27, 15 March 2007 (UTC)[reply]

I might add it later but centrifuges in a non-laboratory setup are often used for seperating two liquids at a fast rate (increasing the "g's", so to speak increases the seperation rate. In shipboard applications, especially, "Purifiers/Clarifiers" (I found the closest thing under Sedimentation, the Engine_room page contains a reference to Purifiers, along with Second_Assistant_Engineer, oh and here is an external link of a picture of one: [2])are used for purification (removing water and sediment), and clarification (removing just the sediment) of farine fuel oils(fuel oil) or lubricating oils(Mineral_oil).Hengineer 00:00, 7 April 2007 (UTC)[reply]

Many industrial fans are centrifugal blowers. They are more efficient that the simple conventional propeller fans.

Industrial cyclones are nothing but simple centrifuges used to remove dust (or particles) from the air.Ck.mitra (talk) 19:58, 29 June 2009 (UTC)[reply]

Finding and Aquriing these for there most common uses[edit]

Hi sorry I kept on adding a link to the centrifuges page without explaining first. Its pretty much my first page edit, I didnt know any better.

Now with that over with I can explain why the link I put up is relevent and why I think it should be included.

The most common uses of Centrifuges are a) in Labs b) on process lines having various uses from peeling to water/oil speration. Bearing this in mind, I think alot of people looking at the page will have process and lab equipment in mind and would be interested in finding out about the Pro's and cons of sourcing these things new and used. Ok I admit that the copy I linked to is a bit sales driven, but it is also actually a hugely useful resource written by an industry leader. In the global recession buying a centrifuge used is a massive time and money saver, and it is a real benefit to people, people who read this page. you could argue that the report isn't specificly targeted at centrifuge but it does cover centrifuge under it's scope along with the other things people are interested in looking at next.

So I would like to put the link to this resource in the footer. Yes its sales'ey, but its also a good relevent resource for the poeple who are actully interested in these things. After reading this they will be better informed about their decisions around finding and acquiring centrifuges. That is why I think the link should be restored.

Thank you for your patience. —Preceding unsigned comment added by Dancave (talk • contribs) 09:26, 7 May 2009 (UTC)[reply]

This is in reference to adding http://www.perryprocess.co.uk/MythsReport.pdf to the external links

The main problems I have with this link are:

Centrifuges are mentioned only twice in passing. - the document is not specifically about centrifuges.
The link essentially advertising for a company, trying to convince it's customers that used equipment is as good as new.
Wikipedia is not a buyers guide - the link seems to be a buyers guide.

Please see Wikipedia:External_links#Links_normally_to_be_avoided and Wikipedia:NOTMANUAL for official policies.

Any third parties with an opinion? --Ozhiker (talk) 11:08, 7 May 2009 (UTC)[reply]

How about a compromise?

I can convince the author to rewrite the document to mention centrifuges in all examples, and I can remove as much advertising talk as possible and references to Perry Processing, leaving only the useful to know info?

While it is not specific to Centrifuges it certainly applys to the topic. Its like having a link to weight watchers (UK national weight loss club) on a page about low fat food, its not specificly about low fat food but it has relevent information people would like to, and benefit from, knowing.

That seems like a fair deal for the user and the person providing the expertise. I'm just thinking that the info is useful, quality stuff and would improve the user experience on this page. —Preceding unsigned comment added by 84.92.24.74 (talk) 12:51, 7 May 2009 (UTC)[reply]

OK I've made the changes and now this really is a useful relevent article which can be sourced and does contain info specific to the Centrifuge. The sales garbage has been removed now too.

http://www.perryprocess.co.uk/8%20myhts%20of%20used%20centrifuge.asp —Preceding unsigned comment added by Dancave (talk • contribs) 12:35, 18 May 2009 (UTC)[reply]

Haemacrotic -> Haematocrit[edit]

I changed the spelling of "haemacrotic" since I don't think there is such a word; the writer probably meant "haematocrit" (related to packed cell volume for red blood cells). I also retained the "ae" usage but I seem to recall there was an international agreement to convert all medical terms involving "ae" and "oe" to just "e" (so heme not haem, fetus not foetus, etc). I could be wrong - it's been a few decades.

Some more images of the various types of lab centrifuge would be most helpful; I no longer work in an industry where I have ready access to different types of laboratory (medical) centrifuge, alas, or I would oblige.

HTH, AncientBrit (talk) 01:34, 8 July 2009 (UTC)[reply]

RCF formula[edit]

I may be mistaken, but shouldn't the second formula (the one using N_RPM) also have g in the denominator? Otherwise RCF would have acceleration units. anonymous — Preceding unsigned comment added by 71.232.18.21 (talk) 02:27, 11 July 2011 (UTC)[reply]

What centripetal acceleration?[edit]

The centrifuge works using the sedimentation principle, where the centripetal acceleration causes denser substances to separate out along the radial direction (the bottom of the tube). I can't make sense of "centripetal". By what force are the particles accelerated towards the axis? Shouldn't it be "centrifugal force"? --92.77.220.225 (talk) 04:51, 31 January 2015 (UTC)[reply]

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