Talk:Bailout bottle

Assessment
This article is unlikely to ever be expanded by much - it's a niche topic. As such it is probably better than Stub-class (which its present size may suggest). I'm inclined to assess it as Start-class because it is wikified, referenced and provides more than a definition of the topic. One of the principal differences between these classes is that a Start-class article should be in no danger of deletion (see WP:WikiProject SCUBA/Assessment). Unless there is a proposal to merge this article into Diving cylinder or Diving equipment, I see no likelihood of deletion. It would be nice to find a paper source (dive mag or similar) to establish notability beyond all doubt, but I don't think that is essential. Any other thoughts? --RexxS (talk) 01:31, 29 April 2010 (UTC)
 * I think this works well as a separate topic but should probably be expanded to discuss why we bailout more directly. My bailout bottles are not "significantly smaller" and do not really fit the current "focused" definition of the term. I put this reference in the rebreather article a year ago:
 * Pictures would help... (Maybe the shot of Simon and Trevor in the rebreather article) Thanks for all the assessments RexxS! --Gene Hobbs (talk) 04:03, 29 April 2010 (UTC)
 * Pictures would help... (Maybe the shot of Simon and Trevor in the rebreather article) Thanks for all the assessments RexxS! --Gene Hobbs (talk) 04:03, 29 April 2010 (UTC)


 * On the issue of definitions, I almost made the content here an expansion to pony bottle as there is a fair amount of confusion on the web between people who group together pony and bailout bottles, since they are both used to "bail out" of a dive, and those who draw a hard distinction between those with integrated regulators (bailout) and those that are basically small normal cylinders (ponies). As a rec diver who knows very little little about what he is talking about, a pony seems largely indistinguishable from a stage/deco cylinder, with the sole difference being that the pony is a reserve that, notionally, is not used except in emergencies.  I could easily see this and pony bottle grouped together either in a single article or under another article, but I couldn't think of a logical way to do it that didn't require far more effort than I want to put forth, so started a new article.
 * In any case, thanks for all the attention. I didn't expect anyone to notice it. - BanyanTree 07:58, 29 April 2010 (UTC)

Merge with Alternative air source and Pony bottle? and redirect
These three concepts are largely interchangeable, and at the least overlap to a very large extent. It is possible that a merged article will be more useful and less redundant, and will be easier to maintain. I suggest the article be called Alternative air source (diving), and that redirects be set up for all the synonyms. Peter (Southwood) (talk): 08:57, 2 August 2011 (UTC)
 * I also prefer to see larger, comprehensive articles, rather than numerous scattered stubs, so I'm sympathetic to this proposal. Off the top of my head, I'd suggest the following schemes could be covered:
 * "Air2" - demand valve on the BCD power inflator;
 * octopus, both traditional and long-hose;
 * Spare Air;
 * other bailout cylinders (used with open-circuit, with rebreather, with surface supply);
 * pony bottle;
 * independent twin set;
 * twins with isolating manifold (traditional regulators and Hogarthian).
 * Any more? As for the name, Alternative air source is the correct title (no parenthetical disambiguation needed). Secondary air supply is already a redirect. The redirects that are not synonyms can be pointed to the appropriate section of the new page if the page is organised by type of alternative air source, which I would recommend. The only problem I foresee is the acute lack of references, so I'd suggest making use of PADI Encyclopedia of Recreational Diving, BSAC Sport Diver Manual, GUE fundamentals of better diving, or similar training manuals as they are likely to cover the bulk of this topic. If you're short of references, I'd always recommend dropping a note to Gene Hobbs as he maintains one of the largest online sources of diving materials in the world (Rubicon Research Repository) and always knows where to find stuff! --RexxS (talk) 12:57, 2 August 2011 (UTC)


 * OK, I will tag the articles for merge and redirect as discussed. Peter (Southwood) (talk): 07:57, 11 October 2011 (UTC)


 * Don't think this merging would work at all. In diving usage the terms are very separate, even if the different systems may be attempting to solve similar problems.  Users looking up any of these separate system (eg spare air, pony bottle etc) will NOT think of them by the term "Alternative Air Source".  So for ordinary users referencing Wiki this common catagory is confusing.  Nor is the usage of All Alternative Air Sources the same.... A Pony is only used as a backup for carrying an emergency ascent, a twinset for use during the dive itself, the octopus is not a redundant air supply itself etc etc.  The more I think about it the more I see this restructuring as VERY confusing  — Preceding unsigned comment added by HowieKor (talk • contribs) 00:00, 31 October 2011 (UTC)


 * @HowieKor: The proposal includes redirects. Anyone searching for one of the separate systems by name would automatically find the merged page, where the leader paragraph would explain that there are several terms for variations on the concept. To me that deals with the nomenclature objection. You may not agree. The point is that we have the option of several small articles with very little useful information, or one with quite a lot of useful information, which, after reading, might leave the reader with a wider and deeper knowledge of the subject, including the various alternative terms and ways to solve the problem. It also reduces the maintenance load, as there will be less need for redundant content, whic would be neccessary if the pages stay separate. I do not share your view that the restructure would be confusing, perhaps you could be more specific about how and why? Peter (Southwood) (talk): 05:05, 31 October 2011 (UTC)
 * @HowieKor: An alternative would be to expand Alternative air source to what I think it should be, leaving the others as they are, and then you can re-assess the options. This would probably be more administrative work in the long run, but not so much as to make it a big problem. Cheers, Peter (Southwood) (talk): 05:30, 31 October 2011 (UTC)


 * @Peter: My concern about merging these areas is that divers do not deal with, or think about these various areas under the “banner heading” of alternative air sources, and such a treatment is not only incompatible with common practise,  it is actually confusing.  It is only the MERGING of the subjects I feel is wrong, not the provision of a separate Alternative Air general overview discussion.  Merging the subjects either creates information overload (if all areas treated comprehensively and properly) or it becomes superficial with respect to any particular subject if treated at an overview level.  Further confusion is created because different alternative air sources are also have different supplementary uses – eg Doubles.  As for the fact that there are several “little articles” I would say that this is not because these individual areas are superficial, it is become nobody on Wiki has yet treated them comprehensively enough.  I do accept that in the Pony Bottle subject the alternatives were mentioned in a rather scatter-gunned way, and I have now gone back and remedied that problem.  I would appreciate your view of the present version now.  Best Regards-  Howie Kornstein  —Preceding undated comment added 17:32, 31 October 2011 (UTC).

Invalid metric conversions
The metric conversions currently given in the "Bailout cylinders for use with scuba" section are invalid. By convention, when a cylinder size is expressed in ft3 it refers to the available gas, but when expressed in liters it refers to the actual volume of the cylinder. Thus the use of the "convert" template is inappropriate. See Scuba tank. The inappropriate conversions were added here by User:Lightmouse on 15:49, 14 September 2010. -- 180.251.9.172 (talk) 01:06, 22 September 2011 (UTC)


 * It's very interesting that there are two different measures of volume (breathable gas and bottle volume). One of the features of an international online encyclopedia is that ambiguity becomes important, where it might not matter so much in a local diving club or retailer. The solution would be to find a way of identifying which volume is being expressed. I'm sure the issue must have been discussed somewhere else. I look forward to reading more. Lightmouse (talk) 10:06, 22 September 2011 (UTC)
 * Thank you 180.251.9.172 for catching that. I reverted the insertion of convert templates in the and  articles, making the same points in the edit summaries as you make here. It seems I missed that change here amongst the other changes which were quite appropriate. I've now changed this article to reflect the conventions and left a note in an html comment for future editors. I almost left Lightmouse a note on his talk page a couple of days ago, but decided not to, as it seemed rather churlish considering all the good work he does. There's no easy way to determine programmatically the places where convert is inappropriate, and it's probably easier on the handful of occasions for us to just to put things right manually. Of course we'll still have to answer readers who say "But 6 cubic feet is not 0.8 litres", by explaining that a '6-cubic-foot dive cylinder' actually is a '0.8-litre dive cylinder'. --RexxS (talk) 17:35, 22 September 2011 (UTC)

Thanks for the further comments. Some sources including Diving cylinder use the term 'water capacity' for the internal volume of a cylinder. Although 'internal volume' seems self-explanatory. I've seen terms like 'free gas', 'free air', 'free gas volume', 'free gas capacity' for the alternative volume. I'd find it easier to understand if somebody wrote something like: Lightmouse (talk) 17:39, 23 September 2011 (UTC)
 * "the cylinder has a volume of 6 cubic feet (free gas), 0.8 L (internal)"
 * My cylinders are all stamped with their 'water capacity', e.g. "WC 12.0 L", so you could write "the cylinder has a volume of 0.8 L (internal)", but I'd be much more wary of writing "the cylinder has a volume of 6 cubic feet (free gas)" because the cylinder doesn't have that volume; it's actually a property of the gas inside and depends on the pressure that the cylinder is filled to. However, I would write "an 80-cubic-foot cylinder has an internal volume of 0.4 cubic feet". These designations are much more of a "label" that we use to refer to a particular cylinder as in "an 80-cubic-foot cylinder" or "a 10-litre cylinder" - obviously in the adjectival form. If you look at where these are used in the article, it's in the context of giving readers an idea of how useful different sized bailout cylinders are, and I'd say that it is most sensible to use the same designations that the reader would come across wherever they lived. I do agree that Diving cylinder should explain the different conventions: please let me know if you feel it doesn't and I'll try to improve the text there. I'm not sure that repeating the explanations here and in Pony bottle, for example, should be needed, but I'd be willing to be convinced otherwise. --RexxS (talk) 19:43, 23 September 2011 (UTC)

Yes. Apparently on an international encyclopedia, we have three requirements when describing the two volume types: make sense in regionA; make sense in regionB; make arithmetic sense. If 'internal' is an acceptable description for one volume type, we only need to find an acceptable description for the other. Disambiguation wouldn't need to be applied to every instance of volume, just those where ambiguity is possible for a reasonable reader. Now that I know a bit more about this issue, I can see it addressed within Diving cylinder, but it wasn't clear to me before this discussion. So I'd welcome more work on it. I may even have a go myself and I'll be happy to have it reverted or reworked by you guys. Incidentally, I see it uses the term "free air equivalent" and User:180.251.9.172 uses the term 'available gas'. Both those terms would work for me, although the latter has the gas type and pressure problems you (RexxS) referred to. Lightmouse (talk) 09:59, 24 September 2011 (UTC)
 * "The cylinder has a volume of x" or "A x cylinder" fails two requirements.
 * "A cylinder with a volume of y has a volume of y " fails two requirements.
 * "A cylinder with a volume of y has a volume of y " meets three requirements.
 * Is this something that should be noted for diving articles in the tabular appendix to MOSNUM? Tony   (talk)  13:41, 24 September 2011 (UTC)
 * @Lightmouse: I'd be most grateful for a fresh pair of eyes looking at the issues, particularly in Diving cylinder (as Bailout bottle and Pony bottle ought to sections within that article, IMHO). Quite often, I find I am too immersed in the jargon to be a good judge of what others will understand. "Internal volume" is fine for the metric case, as "water capacity" is probably part of the jargon. The commonest expression that I'm used to seeing in the literature for the USA convention is "free air", but it is more common today for diving cylinders to hold other breathing gases as well, so it may be considered a misnomer to the purists.
 * @Tony: That's a good point and I seem to remember mentioning it to you at MOSNUM before we all got distracted by the date-delinking saga. I'd certainly welcome documentation at MOSNUM of the different conventions for cylinder capacity between the USA and elsewhere. It's part of a wider problem related to diving, where nobody uses SI pressure units: it's normally psi in the USA and bar elsewhere, although older sources tended to use ATA (atmospheres absolute) for making calculations – you just don't see any literature using kPa. I suppose to meet our requirements as Lightmouse describes, we probably ought to provide 3 pressure values: in psi for the US audience; in bar for the worldwide diving audience; in kPa for non-divers worldwide. Or do you think that would be overkill? --RexxS (talk) 16:21, 24 September 2011 (UTC)

Lightmouse (talk) 18:44, 24 September 2011 (UTC)
 * I try to avoid 3 units in a conversion. In fact, I've been discussing that issue at the convert template talk page over the last few months. I haven't done much editing or investigating of units of pressure so I haven't formed an opinion. I'd like to know more about pressure terminology in other domains and other regions. For now, I'd say just add bar. I'll think about it more and we can revisit the issue later.
 * The term 'water capacity' is very clear when you know what it is but I got confused because I thought it was the capacity when the diver got into the water. So I'm happier with 'internal'. I suspect the term 'free air' refers to the air surrounding the cylinder rather than the contents of the cylinder. So purists should be able to accept that term. However, it might be better to have a term that refers to standard atmospheric pressure. I presume the industry uses the values in the International Standard Atmosphere...
 * When I was writing Oxygen toxicity, I tried to work in bar and provide kPa conversions because of the MOSNUM guidance. Older sources did use ATA and psi (particularly those related to the space industry). Perhaps I ought to revisit that and provide psi conversions, as everybody works in either bar or psi nowadays.
 * You would commonly hear a diver say "that cylinder holds 80 cu ft of free air", meaning that when the compressed air inside the cylinder is released ("freed") then the volume of air would amount to 80 cu ft at normal pressure, but I think any of the alternatives you've suggested would be fine.
 * As for international standards, the ambient pressure on divers increases by about 1 bar or 1 ATA for every 10 metres (33 ft) of water they descend, and divers have to breathe air at the same pressure as their surroundings, which means that air consumption increases quite rapidly with depth. As a result, when divers calculate how much air they will need for a particular dive, the differences in surface air pressure are negligible compared to the effect of depth. So the answer is no, nobody worries about the fine points of the International Standard Atmosphere in cylinder calculations – cylinders are pressurised to more than 200 times the surface air pressure and divers may well be breathing air at 5 bar on a deeper dive. Even small errors in measuring those will swamp the effect of surface pressure variations.
 * Thanks for your thoughts on these issues – it's rare for me to be able to bounce ideas off someone with a good grasp of the problems who isn't already immersed in diving jargon. --RexxS (talk) 22:32, 24 September 2011 (UTC)

Thanks for explaining that variation in atmospheric air pressure isn't an issue. I'm reluctant to pick a term myself. Can we look at specific examples: I'd prefer you guys to choose the non-internal term. But I edited that article to use "(free gas equivalent)". If that doesn't work, please try another term. Lightmouse (talk) 15:22, 28 September 2011 (UTC)
 * A steel 10 L (internal) cylinder rated to hold 72 cubic feet (free gas equivalent)


 * I have jumped in and added a section Diving cylinder, as this is clearly something that needs explanation. Check if it looks OK. If so then it can be used as an explanatory link for dive cylinder volume. Cheers, Peter (Southwood) (talk): 07:41, 11 October 2011 (UTC)

You're right, this issue is something that an encyclopedia can and should do for non-experts like me. I've edited the text based on my understanding gathered from you guys. Feel free to amend or revert it. Lightmouse (talk) 10:46, 11 October 2011 (UTC)


 * Nice prose, but a small amount of information has been lost. However I will leave it as amended and probably put the lost information in another section where it is more appropriate. Perhaps we should try to standardise on terms cylinder volume and cylinder storage capacity. Peter (Southwood) (talk): 11:31, 11 October 2011 (UTC)
 * You've made a good job of that, between you. I have no doubt that someone unaccustomed to diving conventions could read the section and come away with a proper understanding of the differing ways of presenting cylinder capacity. I agree, Peter, that we've lost the part about WP and CP, but I think that may be better in a section explaining cylinder markings. I'll take a close-up photo of the markings on one of my cylinders when I remember, and we can use that as an example of UK-style. --RexxS (talk) 12:57, 11 October 2011 (UTC)

B-Class review
Promoting to B-class. &bull; &bull; &bull; Peter (Southwood) (talk): 13:06, 8 April 2017 (UTC)

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