Talk:Aqua-Lung

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Emile Gagnan and Jacques Cousteau were not inventors of aqua lung, they just developed it. Aqua lung was invented much earlier by other gentlemen, I don't remember the names, but I'm certain. Please check this information. 20.27 & 20:28, 28 March 2007 User:4.68.249.1
 * A similar breathing set was developed in the 1860's by Rouquayrol and Denayrouze, and it had a demand valve, but it was later forgotten. Cousteau and Gagnan did (re-)invent it. Anthony Appleyard 21:29, 28 March 2007 (UTC)

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SCUBA is a trade mark for some forms of diving apparatus in the UK (see http://www.ipo.gov.uk). 20:50, 1 May 2007 User:Esthameian
 * I searched therre, and I found there many references to scuba diving but no uses of the word "scuba" as a tradename. Anthony Appleyard 04:49, 3 October 2007 (UTC)

misleading
in Aqua_Lung_America : "Aqua Lung America, along with Aqua Lung International, is a division of Air Liquide, which held the patent on the first "Aqua-Lung" until the patent expired." In this article, a trademark issue is mentionned between Cousteau/Gagnan and US Divers / Aqua Lung. However, as Gagnan worked for Air liquide which owned US Divers/owns Aqua Lung it seems a very legitimate use of the name.--70.95.119.176 (talk) 04:57, 12 April 2009 (UTC)

Trademark
Hi.

I saw this:

"Presumably, anyone who uses "aqualung" generically now can expect a polite but firm "cease and desist" letter from a law firm representing U.S. Divers."

Hmmph? I thought that a trade mark is only infringed when you market a product under it, not what words you use in your common speech -- does this mean the company is some sort of "language police" now? mike4ty4 (talk) 19:57, 10 May 2009 (UTC)

# marks
Are the # marks in the "See Also" incorrect? — Preceding unsigned comment added by Rb95403 (talk • contribs) 02:30, 7 July 2011 (UTC)
 * They are the correct way to link to a subsection of another article, but it is poor style to display them in the text. I've made them into piped links that should look better. --RexxS (talk) 15:40, 7 July 2011 (UTC)

strange word
in para 4 of Trademark section there's this: "Rge firm Voit provided most of the diving equipment used in this series" - what does Rge mean? Went to disambig page but no wiser. Also needs to be in full at first mention. Tks Manytexts (talk) 03:38, 29 September 2013 (UTC)
 * @Manytexts, Rge is most likely a typo of "The" - adjacent keys struck by accident and not checked. Often happens to me. I have made corrections.
 * After reading your talk page I think it will amuse you that it took me a Google search, reference to a book on vintage scuba equipment and about 15 minutes of research to spot the obvious... Cheers, &bull; &bull; &bull; Peter (Southwood) (talk): 08:53, 29 September 2013 (UTC)
 * it does amuse me – you're a champion searcher and spotter of my humour! Manytexts (talk) 11:40, 1 October 2013 (UTC)

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Reason for two hoses
The article states "...Aqua-Lung's patent on the double hose regulator. This patent involved the return of exhaust gas to the regulator to reduce the differential pressure and therefore reduce work of breathing." I'm pretty sure it has nothing to do with the work of breathing (exhaling), since there's no more work in exhaling from a single hose regulator, and the exhaust ports of a single hose regulator are positioned more or less exactly where the exhaust port of a one-stage regulator (which the original double hose regulator was) would be if it had only one hose, namely just outside the mouth. Rather, the reason for the return hose is so the exhaust port and the diaphragm regulating the first stage are at (almost) exactly the same position, thereby preventing free-flow in certain positions: if the exhaust port is significantly higher (like ten inches or so) in the water than the diaphragm, the resulting pressure difference will cause the regulator to continually dump all its air out the exhaust. One can demonstrate this principle with a two-hose regulator by removing the mouthpiece from ones mouth and holding it at a position above the regulator: the air starts to continually flow (free-flow) out the mouthpiece. Indeed, this was once a recommended way to "clear" (purge) a regulator that had become filled with water, before the use of one-way valves where the hoses connect to the mouthpiece essentially prevented the hoses from filling with water--the mouthpiece could flood, but is such a small volume that even a small amount of breath can clear it.

I seem to recall that Cousteau mentions this reason for having two hoses when he describes the invention of the aqua lung, probably in Silent World.

A single hose regulator will not free-flow, since the exhaust ports (and the mouthpiece) are exactly adjacent to the second stage diaphragm--which is why they used to (and for all I know still do) have a manual purge valve, in case you're *really* out of breath. Mcswell (talk) 02:21, 18 June 2020 (UTC)


 * Work of breathing has an inhalation component and an exhalation component. If there is a difference in pressure between the diaphragm (supply pressure) and the exhaust port (outlet pressure) this will either resist the flow (making it harder to breathe) or encourage it (and a free-flow will ensue). A regulator with the exhaust port significantly distant from the diaphragm, such as a twin hose with the exhaust hose removed, will be extremely sensitive to diver trim. Face down it will require significant effort to inhale, not much to exhale, so negative pressure inhalation, possibly slight positive pressure exhalation, with net positive work of breathing. With the mouthpiece above the diaphragm, it would provide positive pressure breathing if the exhaust valve did not open to free-flow, but the exhaust valve does open to allow free-flow, so the positive pressure just blows off the gas to the environment. In effect, having the diaphragm and exhaust valve separated makes work of breathing variable with posture, and the regulator is prone to freeflow when the exhaust valve is higher than the diaphragm. A completely consistent WoB requires the diaphragm and exhaust valve to remain at the same depth as the lungs, which is not physically feasible. Keeping them at the same depth as each other stabilises WoB as much as is reasonably practicable. and eliminates most free-flow problems. Most divers spend most of their underwater time with the regulator at much the same depth as the lungs, so WoB does not vary greatly. Without checking the wording of the patent, I cannot say what the claimed reason was, but either would be valid. Cheers, &middot; &middot; &middot; Peter Southwood (talk): 08:25, 18 June 2020 (UTC)

Copyright problem removed
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