Talk:Vacuum/Archive 1

message: 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: ?
--8472 17:23, 3 September 2005 (UTC)
replies: text: 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)
thread_title: Units

message: 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)
thread_title:  Perfect Vacuum 

message: 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)
replies: text: 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)
thread_title:  Historical interpretation 

message: 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)
thread_title: Comments

message: 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)
thread_title: Requests

message: In this section, the term "conflat flanges" is used. "ConFlat Flange" is a registered trademark of Varian, Inc (  ). 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)
thread_title:  Ultra-High Vacuum 

message: 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)
thread_title: Human body in space Vacuum

message: 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)
thread_title:  Record vacuum 

message: How airtight is the vaccum in a thermos?
Pretty tight I would say!--Light current 18:30, 14 January 2006 (UTC)
thread_title:  suggestion 

message: 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)
thread_title:  Definition of vacuum 

message: 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)
thread_title:  The temperature of outer space 

message: 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)
thread_title: Types of Gauges

message: 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)
replies: text: 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)
replies: text: 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)
replies: text: 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)

text: 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)

text: 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)
replies: text: 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)
thread_title: "Quality of Vacuum" section