Talk:Vacuum/Archive 1

Units

Shouldn't we put the SI Pa units first instead of torrs first? Samw

I have just done this. With all due respect to Evangelista Torricelli, I would prefer to rid the page of the references to the torr. I feel that all that is needed is a statement explaining that the torr may be used to measure the pressure within a vacuum. AlexanderWinston 01:07, 2004 Aug 18 (UTC)

Actually, I have gone ahead with this plan already. There is clearly not much active communication on this talk page, so I decided to be bold! AlexanderWinston 01:27, 2004 Aug 18 (UTC)

*shrug* Suit yourself. -- Tim Starling 02:43 May 7, 2003 (UTC)

Someone deleted all reference to the Torr. The SI crusade has gone too far in this case. It is difficult to find vacuum equipment specified in Pascals; the Torr is the de facto standard. If a reader is going to an encyclopedia article to learn about vacuum, it would probably be useful for her or him to know what a Torr is and how to convert it to Pascals. I put it back in. Yannick Trottier June 4, 2005

At least give the values in Pascal to. I can work fine with Pascal, but have no idea what a Torr is, and it might be visa versa for somebody else. It seems prudent to have them both. How about this: Alternative vacuum ranges image? --8472 17:23, 3 September 2005 (UTC)

Torr is the industry standard from my point of view, manufacturing wood drying vacuum kilns. - Garrett

Industry standard where - US, UK? I really think this article should be made solely SI unit article: The dualism is highly confusing and doesn't serve any purpose - The measured value doesn't change regardless of unit and as pascal is the standard unit, not mmHg, then why not use it? If you want to keep torrs add another section where you point out that torr is still often used with a link to a page (Torr page probably) with appropriate conversion formulas. - G3, 00:45, 28 January 2006 (UTC)

The Pascal is not the standard unit in this field. I have worked with vacuum pumps from several US manufacturers, a couple from France, and one from South Africa. All of their specification sheets were written in Torrs, with no reference to Pascal units. The bulk of the article is already written in Pascals, and all references to Torrs are in dual units. Wikipedia is an encyclopedia documenting real-life systems, not a soapbox for the SI system. I agree that the industry would benefit from going metric, but it's not there yet, and I don't think it will bow to pressure from Wikipedia. --Yannick 04:32, 28 January 2006 (UTC)

If you want to make this article scientific or universal instead of mechanical then Pascal is the standard unit. If you want to keep torrs then change this article to Vacuum pumps instead of vacuum. G3, 11:28, 29 January 2006 (UTC)

I did some research. I searched google in my language for vacuum pumps and came up with references to pascal or bars (hechtopascals), I didn't find any mention of mmHg, at all. Therefore claiming torrs as universal industrial standard is at the very least misguided. Furthermore, for example, the German version of the article "fails" to mention mmHg completely and the French version, while mentioning bars & torrs as industrial units, uses pascals and molecular density in the article. -G3, 12:13, 29 January 2006 (UTC)

I just checked Google as well and got different results than you. The top two vacuum companies that came up for me were Busch and KNF, both German companies. I also checked Varian and Kurt J. Lesker, big American vacuum companies that I am familiar with. Busch provided data in Torr and inHg. KNF mentions Torr and inHg on its front page, and additionally showed millibars on its American datasheets. Varian uses Torr as a primary unit with millibars in parenthesis. Kurt J. Lesker datasheets were in Torr and Pascals. This confirms my past experience (I've worked with a lot of vacuum systems, both scientific and industrial) that the Torr is the universal vacuum unit, at least in the English language. Maybe it's different in other languages, and that should be mentioned, but this is the English version of Wikipedia. I don't mind having most of the article in Pascals, but eliminating the Torr would be a diservice to our readers who will, more than likely, have to work with data in Torrs.--Yannick 05:03, 30 January 2006 (UTC)

To add our vendors to the list: according to their manuals, Duniway uses Torr, and occasionally Pa; Alcatel (Adixen) uses only mbar; Austin Scientific and McAllister use Torr. IMHO, Wikipedia is supposed to be a prime reference, like a science textbook, so SI units should be the primary unit. But like Yannick, the equipment coming into my lab was almost all in Torr, so it's extremely convenient to have that listed too. (Sorry, I forgot to sign this before.) Mwistey 03:16, 12 March 2006 (UTC)

Perfect Vacuum

Why is perfect vacuum impossible? Don't small volumes of completely empty space always exist betweem molecules? Aren't there larger volumes in space?

Answer: look down to the section on Quantum-Mechanical Vacuum in the article. --Yannick 01:05, 30 October 2005 (UTC)

According to intergalactic space article the level of vacuum between galaxies can be on the level of 1 atom in a cubic meter, or below. Taking a slice of that space and not calling it a vacuum (matterless space) is IMO completely a philosophical standpoint: Standard dictionary definition of vacuum is absence of matter, not absence of energy/quantum fluctuations. - G3, 00:44, 28 January 2006 (UTC)

That slice of space is going to include a slice of the atomic cloud due to the Heisenberg uncertainty principle. Furthermore, matter is a quantum wave, so when we talk about quantum fluctuations in a vacuum, that includes virtual matter.--Yannick 04:42, 28 January 2006 (UTC)

In average virtual particles don't exist: The distinction with matter and virtual matter isn't arbitrary but based on measurable properties and relative permanence of matter. As for not being vacuum based on probability mathematics...I'll point out that even if there's a probability that a slice of space contains a particle there also is a probability that in any given moment the slice is completely void of matter (assuming the slice is already located somewhere in sparse intergalactic medium and is sufficiently small). So, absolute perfect, matterless, localized vacuums can exist in a classical sense even if only for short periods of time. G3, 12:07, 29 January 2006 (UTC)

It's not just probability mathematics. Unobserved particles are not local and have a sort of distributed partial existence which propagates like a wave. As a common example, each photon is capable of going through both slits of the classic double-slit experiment and can interfere with itself on the other side. (Even though experiments that actually prove that are much more complicated.) Yes, it's true that absolute perfect matterless localized vacuum can exist in a classical world, but we don't live in a classical world. It's tough to explain in a single paragraph, but you can take classes in quantum mechanics if you want to explore the concept further.--Yannick 05:02, 30 January 2006 (UTC)

Vacuum in Space

My note about fecal matter in low earth orbit is bizzare enough that it really should have a reference. To my embarrassment, I can't find it, but I'm still sure I read this in one of the Long Duration Exposure Facility (LDEF) studies. Does anybody have relevant conference proceedings?

Historical interpretation

The article mentions one William Burley, about whom I'm not able to find anything. It seems to me that Walter Burley is meant. However, Walter Burley lived 1275-1344 while Bishop Tempier condemned his 219 propositions in 1277 (thanks, ALoan). That would make the article's historical order wrong. More research is clearly needed.
—Herbee 20:24, 14 Feb 2005 (UTC)

Hmm - perhaps is was Walter Burley - I'll have to check my notes. And I wasn't professing to have put things in strict date order, but it is gratifying that they are roughly contemporary. -- ALoan (Talk) 05:26, 18 Feb 2005 (UTC)

Comments

Oops! In the edit summary field for the article I really meant 'avoid redirect', not disambig of course. Andrewa 18:09, 18 Mar 2004 (UTC)

While the cosmological constant figures prominently in some theories, I think it fair to say that it has not actually been observed in nature, despite recent developments and hopes. Guest 03-26-2005.

---Removed link to Vacuum, seems like spam, does not deserve link in external link section.

Requests

If anyone has any pointers on the following

- perfect vacuum, aka free-space and what energy and circumstance is provably required to create such a state of matter-free space

it would be nice to have it included in this article. Thanks so much!

---

Other possible topics or references to add to this article

-pumps in series vs. parallel, explanation of compression ratio and backing pressure

-vacuum measurement

-uses of vacuum - semiconductors, food packaging, adhesive preparation

-particle gas dynamics, i.e. fluid dynamics for vacuums

-effects of exposure to vacuum, on humans, plants, etc.

-the Crookes radiometer, and why it reverses with pressure and temperature

--Yannick 03:46, 6 Jun 2005 (UTC)

---

I added a link to a NASA page discussion effects on humans to exposure to vacuum. As that is what I came to this page to lookup, and it's requested above, it seemed like a reasonable thing to add. -- RichardGaywood 14:42, 14 July 2005 (UTC)

Image requested?

Is this some sort of joke? How does one capture an image of nothingness? Just really curious I guess as to why there is an image request for something that isn't really photogenic... Dismas 02:57, 11 July 2005 (UTC)

Well, one could use any number of things that could be "representational". The one that jumps out at me would be a picture of an alarm clock inside an evacuated bell jar, but I'm sure vacuum tubes, interstellar space, the score from 4'33", and the like could be used.

Atlant 15:30, 17 July 2005 (UTC)

Ultra-High Vacuum

In this section, the term "conflat flanges" is used. "ConFlat Flange" is a registered trademark of Varian, Inc ( [1] ). Varian, Inc. is one of the three companies that resulted when Varian Associates, Inc. split up in 1999. Varian Associates, Inc. was founded by Russell and Sigurd Varian, who are mentioned in the article on Klystron.

Varian, Inc. jealously guards its trademarks. They do not want to have them reduced to common words. So, at first I was going to ask that the term be formatted correctly and identified as a trademark. But I have read the FAQ pages on the use of trademarks in the wiki, and also about the use of camelcaps. So, maybe it would be best to replace the term "conflat flanges" with something generic, such as "special flanges with soft copper gaskets".

--Chris 20:19, 14 November 2005 (UTC)

I disagree. Do a google search on "conflat" - you will find many companies making them without reference to Varian, and without capitalization. Maybe Varian really has trademarked conflat, and maybe a Texas company named RiceTec really has patented basmati rice, but I don't care. Calling them "special flanges with soft copper gaskets" is insufficiently descriptive. It would lead to confusion with ordinary #150 flanges for which you can get copper gaskets, but won't give you the same vacuum seal as that seration on the conflat. --Yannick 03:17, 16 December 2005 (UTC)

My two cents' worth is that we should just call it a knife-edged flange that cuts into soft copper gaskets. :-) Mwistey 16:20, 26 February 2006 (UTC)

Human body in space Vacuum

Would the human body blow up if he/she took off the space helmet? Reason is because the body is made up of gas and liquid, since space is rather cold (depending on distance to the sun) it would also freeze.

Answer: only in the movies. Blood would boil and give him/her the bends, but the porosity of the human body would let out gas plenty fast enough to prevent an explosion. Blood would not freeze until the astronaut's body had cooled substantially, which will not happen if he/she is in view of the sun.--Yannick 03:09, 16 December 2005 (UTC)

For similar reasons, I doubt and have deleted the following claim: "Robert Boyle later conducted experiments on the effects of a vacuum. For example, a canary exposed to vacuum would rupture open due to the lack of pressure." Please cite your source.--Yannick 27 December 2005 (UTC)

Record vacuum

Does anybody have a reference for the statement in Ultra-high vacuum that 10^-13 Pa have been acheived in a laboratory? I have trouble believing that. --Yannick 03:46, 16 December 2005 (UTC)

That does sound unlikely. Perhaps inside a dilution refrigerator? I could believe 10^-13 *Torr*. CERN's LEP collider hit 5x10^-13 Torr: http://dbnetra01.cern.ch:9000/pls/ttdatabase/docs/F22606/THZ02A.pdf . Mwistey 13:30, 27 February 2006 (UTC)

After some research, the lowest I found was an article that described a 3x10^-13 Torr, but they didn't claim it as a record. I changed the statement to Torrs until we find better info.--Yannick 06:10, 15 March 2006 (UTC)

suggestion

How airtight is the vaccum in a thermos?

Pretty tight I would say!--Light current 18:30, 14 January 2006 (UTC)

Definition of vacuum

The first sentence of the article should define what vacuum is, rather than what it is not. An note that perfect vacuum is impossible does belong in the first paragraph since it is a common misunderstanding, but not before the definition of vacuum. The etymology of the word is also relevant to the first paragraph, but not more important than the actual definition of the word.--Yannick 04:50, 19 January 2006 (UTC)

The temperature of outer space

Bowlhover stated:

outer space has no temperature

Of course it has a temperature. Everything with any atoms or molecules vibrating or zipping around has a temperature. In fact, the atoms and molecules in space are zipping around pretty rapidly so its temperature is probably pretty high. What outer space doesn't have much of is heat; this is due to the fact that there are so few atoms and molecules out there.

Please note that I didn't revert your deletion because the statement you deleted (that space "is cold") isn't too technically accurate either.

Atlant 02:10, 14 February 2006 (UTC)

Types of Gauges

I put in a section with types of gauges for whoever was too tired. Most of this stuff is from BSA, especially the ranges of effectiveness, which seem a little conservative for my experience, so comments on them would be appreciated. Does anybody have any pretty pictures or graphs to go with this section? Because it could definitely use some.--UltraHighVacuum 02:40, 23 February 2006 (UTC)

"Quality of Vacuum" section

I don't want to trigger a revert war over this, so I'm curious how various other fields break down the lists of vacuum. In MBE, UHVCVD, and most physics labs I've toured, UHV always meant baking the chamber, i.e. 10^-9 Torr (100nPa). But at higher pressures? According to the definitions provided, high vacuum would start at 10^-4 Torr for a large MBE chamber. Perhaps we could leave gaps as disputed territory? Also, does anyone have a definition or good reason to add Extremely High Vacuum below 10^-12 Torr (100 pPa)? Mwistey 17:48, 26 February 2006 (UTC)

I can reference a couple of texts with different numbers, but they wouldn't resolve the issue. There is no agreement on the numerical thresholds, and dispute gaps would have to be pretty large. I stand by my high vacuum definition based on MFP, but note that it's not always the chamber size that matters. Sometimes the ion gauge size or the microchip size is more relevant. I disagree with your revised definition of ultrahigh vacuum. I have worked with low vacuum systems that were baked and UHV systems that were not. I've generally found "ultrahigh" to be a marketing term, and I don't remember seeing a reference to EHV. If it was just up to me, I'd delete everything but the low/high categories. This section first came into existance because of an unreferenced graphic chart that people accepted as authoritative.--Yannick 04:08, 27 February 2006 (UTC)

As have I (baked/unbaked), but I think it's as good a rule of thumb as the rest. If outside references are helpful, MDC claims (http://www.mdcvacuum.com/searchs/doc/Glossary.htm): "Ultrahigh vacuum; defined by the American Vacuum Society as the pressure range between 7.5E-10 to 7.5E-13 Torr; British and German standards define UHV as 1E-8 Torr or better." I could not find the primary sources for these statements, though. Mwistey 13:55, 27 February 2006 (UTC)

I'd say that's more authoritative than much of the material on Wikipedia, even without primary sources, and it's compatible with my favorite textbooks. Good find; that belongs in the article. --Yannick 03:05, 28 February 2006 (UTC)

I finally found a source at AVS (via AIP): see Vacuum at http://www.aip.org/avsguide/refguide/glossary.html, including VHV and defining UHV as 10^-9 to 10^-12 Torr. It's not a primary source (official standard) AFAIK, but better than nothing Mwistey 04:11, 12 March 2006 (UTC)

Oh, and I modified "Outer Space" to "Deep Space" in two places, to be consistent with Outer Space. If someone mods it back, please fix both statements that it's more empty than "artificial vacuum." Low earth orbit is about 10^-6 Torr, which is easy to reach in the lab or industry. Mwistey 17:48, 26 February 2006 (UTC)

LEO is a broad range of altitudes, and the pressure varies by orders of magnitude depending on altitude and weather. And 10^-6 Torr is not easy for everyone; many auto shops use vacuum but have trouble conceiving of vacuums that low. It is almost always correct to say that the vacuum of space is more empty than artificial vacuum.--Yannick 04:08, 27 February 2006 (UTC)

You're not going to hit 10^-6 Torr by sucking on a Coke bottle. :-) But I've used an evaporator (i.e. a dirty system) that hits low -7's within 3 hours after air exposure, 3-5 times a day. That's better than what the space shuttle sees. Not hard. Mwistey 13:55, 27 February 2006 (UTC)

To Do List

Great job, everybody! This article is in very good shape, and with a few more fixes we should be ready to start the featured article submission process. To help focus that effort, I've started a to do list at the top of this page explaining improvements that I think the article still needs before peer review. Please feel free to add/subtract to this list or debate my ideas.--Yannick 04:40, 23 February 2006 (UTC)

"Vacuum lines" are sometimes used by chemists and most likely other scientists. I think it would be a good idea to have a practical section or article somewhere in Wikipedia on vacuum lines (manifolds), cold traps, vacuum distillations, etc. as used by chemists and similar scientists. However, this article has become rather long. Maybe a shorter section on vacuum lines can be written up for starters to be eventually separated into a new article on vacuum lines? Any thoughts? H Padleckas 11:00, 24 February 2006 (UTC)

This sounds to me like a good idea, and I agree that it should probably be a free-standing article with a brief reference in this article. Don't forget that vacuum lines are also extensively used in hospitals and other medical environments where suction is required. So, yes, be bold and have a go at it!

Atlant 16:25, 24 February 2006 (UTC)

I added a similar item to the To-do list at the top of the page calling for a new section which may be called something like "Practical application of full or partial vacuum". Maybe I should have added it to the "Requests" section further down instead. Some day, I may develop the ambition to write this section, like hopefully within a month or two. I think I'll let you know when I start writing it. H Padleckas 11:44, 26 February 2006 (UTC)