Talk:Scuba set

Queries
If an image belongs with a paragraph, I put the image description line before the paragraph's title line so that the image comes as high as possible within the paragraph, to cut down the amount that the image intrudes into the next paragraph. Anthony Appleyard 07:33, 23 Dec 2004 (UTC)
 * I think that concise style implies, that images and text belong under a heading, in fact, no content in a structured article should be outside hierarchically nested headings. By the way -- why is the title of this article in plural? AtonX 10:31, 23 Dec 2004 (UTC)

Sorry to keep re-editing the text, but:- Both types of scuba sets consist of

i) a breathing gas supply stored in a high pressure diving cylinder , Not true with potassium superoxide rebreathers. Arguably not true with liquid-air scuba.

ii) a diving regulator attached to the diving cylinder Not true with constant-flow open-circuit sets or with some rebreathers. We must cover old sets as well as modern sets.

Rebreathers also employ advanced electronics to monitor and regulate the composition of the breathing gas. Not all rebreathers, and not old-type rebreathers. I have been in scuba diving from before divers' lifejackets were heard of. Pony cylinders and stage cylinders are an important feature and should be mentioned. Anthony Appleyard 00:00, 24 Dec 2004 (UTC)

Cylinders, regulators and stages

 * Firstly, in potassium superoxide rebreathers the scrubber filling also produces oxygen, but these rebreathers, too, contain a high pressure cylinder to top up the loop with breathing gas, which gets compressed with the depth! In liquid air scuba, the liquified breathing gas is also stored in a high-pressure cylinder. Thus, I argue, a high pressure cylinder is a general part of both types of scuba sets - aqualungs and rebreathers.
 * Secondly, old constant-flow open-circuit sets as well as some rebreathers contain a constant flow regulator (more correctly - a constant mass flow regulator), whereas the aqualungs and the rest of the rebreathers contain a constant pressure regulator. Hence, generally it is a regulator which is a general part of scuba sets. The term demand regulator is -- in my opinion -- highly misleading. It is technically a constant gas pressure regulator combined with a demand valve.
 * Thirdly, pony cylinders and stage cylinders are an important feature of a diver's equipment, I agree. However, they are just independent aqualung-type scuba sets attached to the diver to enhance his/her safety or gas supply, they are not parts of what this article describes - a scuba set. Logically, you can't say a scuba set is a part of a scuba set. They belong to articles on diving equipment or configuring cylinders, otherwise it is just duplicate information in the encyclopaedia. Similarly, wings and/or jackets are not a part of the breathing apparatus. They are attached to the harness, but so is the knife, the light canister, the weights etc.  Here, they are misplaced - for the sake of logic and clarity, they belong to different articles! AtonX
 * 14:30, 27 December 2004 User:AtonX
 * Whether we call pony cylinders part of the same set or another set, is a matter of definition. Anthony Appleyard 23:35, 10 Jan 2005 (UTC)
 * True, and I dont remember seeing a definition stating that they are part of the same set, so can you provide a reference? Peter (Southwood) (talk): 07:44, 18 June 2012 (UTC)

Duplicate sections
An edit note: there were sections of this page that were exact duplicates of previous sections. A copy-n-paste gone wrong? I'm not sure. In any case, I've removed them. Thayvian 19:57, 11 Mar 2005 (UTC)

Spearfishing?
Should we be encouraging spearfishing (by including it in the links) amongst scuba divers, esp given how many organisations dissaprove of it.


 * I agree with you that some divers oppose spear fishing (personally, it's not something I do, and I prefer it not be done when I'm near it in the water), but I don't think it belongs as an italicized comment to the link. My suggestion would be to add a spear fishing segment to SCUBA to bring it up there and cite concerns.  It just doesn't belong as a comment on the link.  Wikibofh 6 July 2005 21:04 (UTC)
 * Perhaps instead we should be linking to the spear-fishing article and debates about ethics could be brought up there? Justin 16:59, 3 January 2006 (UTC)

Nitrox
Would a bit about nitrox be ok here? Justin 17:03, 3 January 2006 (UTC)


 * Why not put it in Enriched_Air_Nitrox? Mark.murphy 19:27, 4 January 2006 (UTC)

Please be careful with the need for an "oxygen cylinder" for mixing Nitrox. The way this is worded makes it appear that the diver has an O2 tank in addition to the "air" tank. Also, most dive shops I know no longer use the O2 mixing method to produce enriched air. The are now "de-nitrifying" air to produce "oxygen enriched air". It is safer and does not require an O2 cleaned cylinder for the diver. I also believe that the author intended the questioned phrase to be something like, "an O2 cleaned cylinder is needed to store the Nitrox". Then a rationale could be given. In fact, an entire section just on production of oxygen enriched air might be in order. 199.244.214.30 (talk) 17:08, 24 February 2009 (UTC)--Reader:dmgambs
 * I've re-written the last paragraph of the section "Open circuit scuba sets" to try to remove the ambiguity. My usual dive shops still use partial pressure blending, so I suspect the phrase "common method" may vary regionally. I've changed it to reflect the lack of consensus for "the most common". Have a look at the article Gas blending as that is the most appropriate place for the section on production of oxygen enriched air (if you think the content already there could be usefully improved). --RexxS (talk) 20:17, 24 February 2009 (UTC)
 * I added the think about valve, I'm not happy with the wording. The point is that the grease and rubber are part of the tank valve, the problem is that our cousins cross-the-pond insist on calling a regulator a "valve" and I'm not sure the best way to bridge our problem of having a common language that isn't.  Suggestions are welcome.  — Preceding unsigned comment added by Wiki4Thal (talk • contribs) 03:01, 18 June 2012 (UTC)

Circular window
"Captain Trevor Hampton in the 1950's or 1960's designed an early single-hose aqualung with a fullface mask with a circular window which was a very big and thus very sensitive demand regulator diaphragm."

Did the circular window somehow act as the diaphragm? --Gbleem 06:53, 26 January 2006 (UTC)

The first 4 sentences of this article
It seems quite odd to me that the first 3 sentences of this article are about the origins of the name. Only in the fourth sentence is the name defined.

Is it really necessary to note the origins of foreign language words at all in this article? It does not seem relevant to this article - this is an English language article on a technical subject. I would probably find this information interesting if I chose to read an article about loan words, acronyms or the origins of words used in Welsh - not here. Even if it is justified, I don't think the origin of a word in any foreign language deserves such prominence on the third sentence in this article. Mark.murphy 22:45, 1 July 2007 (UTC)


 * Hi, all & Mark, yes, it's an oddly oblique start, and then it hit me: the intro does not say what a SCUBA does! The main function is to keep changing the delivered air pressure so that the diver can breath at a changed water depth; for example 44 psi 66 feet down in sea water and 59 psi at 100 feet. I'll change the intro; I hope the community will accept the change and make it better and briefer than I can write it.
 * Jerry-va (talk) 23:15, 15 June 2012 (UTC)


 * I have had a go at revising the whole lead section to be more accurate, and with luck more grammatically correct. Take a look and see if you agree. Peter (Southwood) (talk): 10:59, 16 June 2012 (UTC)


 * I've tweaked the bit about "stored gas is provided through regulators as required" because SCCRs tend to use fixed-rate injectors, not a demand system. Conventionally, we don't normally use guillemets, so I've replaced them with normal quotation marks. It's acceptable to use italics to delineate a definition term (), and for when a word is used as a word, but shouldn't be overused, and I generally prefer quotation marks - see WP:WORDSASWORDS. The point of putting "self-contained underwater breathing apparatus" in the first sentence is that it's a common alternative title, and needs to be bold per our convention on bolding article titles and their plausible alternates - see WP:BOLDTITLE. HTH, --RexxS (talk) 14:20, 16 June 2012 (UTC)


 * I like your changes, but injector nees explanation. You are not referring to a manual addition valve, because you state fixed rate, which suggeste sonic orifice to me. Peter (Southwood) (talk): 09:07, 17 June 2012 (UTC)


 * I'm torn between explaining WP:JARGON and respecting the convention that the WP:LEAD of an article just gives an overview without going into too much detail. The detail really belongs in the body of the article (or in daughter articles). For the moment, I've wikilinked to Rebreather and Rebreather, although I'm aware that CCR rebreathers may also "inject" gas into the loop. The SCCR system I am most familiar with is described here: http://www.halcyon.net/node/49 in the Semi Closed Active Addition section, but I accept that other mechanisms exist. The Draeger Dolphin has been quite popular in the UK as well. --RexxS (talk) 12:29, 17 June 2012 (UTC)


 * A link is good. I think the explanation is more appropriate in Rebreather, as long as there is one there. There has been a lot of creep in 'Scuba set' with a tendency to put in stuff that is more appropriate in other articles. I have had a bash at cleaning it up. Apologies for inadvertant errors, but I think it is now tighter and more consistent, with less waffle than before, and probably a new outbreak of typos.
 * The semi-closed active addition system is usually a sonic orifice, either a fixed orifice or a needle valve. I am fairly familiar with the theory and practical examples, including the Dolphin, and it does seem like these are commonly referred to by divers as injectors.Peter (Southwood) (talk): 10:45, 18 June 2012 (UTC)

FDA
Regarding this sentence: Exotic gas mixtures presently used in scuba are intended to prevent decompression illness in diving, but officially, the FDA appears to continue to believe that scuba divers all use compressed air.

Either the FDA "officially" recognizes something or they only appear to recognize something because it isn't official policy. Instead of conjecturing as to what their policy may or may not be, how about finding a reference? Mojodaddy (talk) 14:50, 20 November 2007 (UTC)


 * Added a "citation needed" to this claim. —Preceding unsigned comment added by 71.16.78.252 (talk) 14:13, 11 June 2010 (UTC)


 * Agreed. I can't find a source saying that the FDA appears to believe that all scuba divers use compressed air (officially or otherwise). The sentence seems to be editorial comment based on (i) The FDA designates non-air gas mixtures intended to prevent or treat diseases as drugs (sourceable); (ii) The FDA does not regulate the use of other gases in scuba diving to avoid DCI (may be sourceable, but more likely an inference from the lack of FDA regulation). That is a kind of synthesis and is WP:OR without a reliable source which states that conclusion. --RexxS (talk) 17:47, 11 June 2010 (UTC)
 * You can modify the wording, but you cannot escape logic. If the FDA has no regulation on scuba breathing gases intended to prevent DCI (as it certainly does on the oxygen to TREAT DCI-- look at those dive boat kits), then that MEANS it does not regulate these gases for this purpose. Lack of regulation = does not regulate. This is not a synthesis; this is a restatement of plain English. If you can't do that much, you're going to have hard time writing an encyclopedia. As for the rest, if the FDA regulates all exotic gases for the purpose of preventing diseases (as they state they do), and DCI is a disease (do you need a reference), and the FDA does not regulate exotic scuba gases for the prevention of DCA, it is a matter of simple logic to determine that the FDA either does not know about exotic scuba gases (unintentially ignoring them), or is intentionally ignoring them, or else is making a erroneous statement in its initial regulatory claims of coverage. There are no other possiblities. WP:SYN does not include arithmetic, and it does not include logical syllogism. If all men are mortal {citation provided} and Mr. X is a man {citation provided} then I can write in his bio that he is mortal and don't need a cite for that. S B Harris 18:46, 11 June 2010 (UTC)
 * One of the problems for a minority sport such as ours, Steve, is that we have a lack of recognised pundits and very few researchers – Peter Bennett & the folks at DAN, our own Gene Hobbs and the team at Duke come to mind; but then who? Even so a lot of the real research is a spin-off from projects on human spaceflight or aviation – there's little funding for scuba research. The result is that we don't fit Jimbo's idea of sourcing – the "if it's worthy of inclusion, somebody reliable will have said it" kind of view. That's what our policies are built around, and with the best will in the world, your chain of logic doesn't fit that scheme. All that you say is logical, and my personal view is that I'd agree 100% with the truth of it. Unfortunately, I still can't find anybody more eminent than you or I who has published the point about the FDA and breathing gases. No matter what we think, as soon as any of us put together two sources and draw a conclusion, we fall foul of the OR policy, even if it's logical (the directly and explicitly supported by the source phrase in WP:OR). We might be able to argue the exception for something being obvious (we don't need a source for "the sky is blue"), but I doubt it would hold up in this case. I've no intention of modifying the wording, but I couldn't honestly object if someone else chose to. --RexxS (talk) 23:44, 11 June 2010 (UTC)
 * Yes, but Wales is simply wrong, if you take him at his literal word, and the policy illustrates this. The policy WP:CALC, which is cited within WP:NOR actually proves he's wrong; is an admission that he's wrong. If he were right, there would be no reason to have the WP:CALC policy at all-- any calculation answer which is true, should be easy to find a citation for, according to what Wales says. But it isn't. S  B Harris 01:30, 12 June 2010 (UTC)

Ambiguous
"Still, most semi-closed systems allow at least twice the duration of open circuit systems (around 2 hours)."

Which lasts 2 hours, the semi-closed or the open circuit? —Preceding unsigned comment added by 172.132.129.187 (talk) 00:17, 7 January 2008 (UTC)


 * The semi-closed. The preceding paragraph illustrated a 40 minute duration for open circuit. RexxS (talk) 01:32, 12 January 2008 (UTC)

Air Cylinders section
As this article has been around for some time, I thought I should flag up a revision I'm about to make. The article states "The drawback is that aluminium cylinders are neutrally buoyant when full, and positively buoyant when nearing empty. This results in having to monitor buoyancy during the dive more closely..." Why should a correctly weighted diver need to monitor more closely? The change in buoyancy as a cylinder empties is precisely the weight of air lost (about 1 lb for each 14 cubic foot of free air). It simply doesn't matter what the cylinder is made of. The real drawback of Al cylinders compared to steel is that they tend to be much thicker (and heavier despite the lower density of Al). This increases the total volume of the diver+set, which equates to a greater total weight to carry out of the water. RexxS (talk) 01:45, 12 January 2008 (UTC)

First and second stage, automat and dry suit
The first stage: is the section between the air bottle (using an INT or DIN-connection) and the pillar valve and serves to lower the bottle pressure to a lower (medium ? or breathing (low)?) pressure. The second stage: runs from the pillar valve to the mouthpiece (breathing/low pressure ?)

The pillar valve thus contains the valves required to reduce the air pressure.

A automat (not mentioned in article), is thus simply an air hose with a attached component.

The above needs to be integrated to the article/clarified.

Another question: there is a connection of the bottle to the dry suit (if one is used), but does this actually consume air, or is it simply hermeticly sealed. Also, I'm wondering whether air from the dry suit and from the buoyancy regulator (trimjacket) can actually be reused (to increase available air).

KVDP (talk) 14:29, 8 January 2010 (UTC)


 * The pillar valve is the top part of the diving cylinder. It contains a screw-valve operated by a knob which turns the supply on or off. It does not otherwise regulate the pressure. The pillar valve has a connector allowing the first stage of the diving regulator to be attached to it.
 * The connection between the diving cylinder and the diving regulator is an 'A' clamp or DIN screw fitting (either 5 or 7 thread for 232 bar or 300 bar equipment respectively).
 * The first stage is the first part of the regulator and is the part attached to the cylinder. Its purpose is to reduce the high pressure of the cylinder to an intermediate pressure (about 10 bar above ambient pressure).
 * The second stage is connected via a flexible hose between the first stage and the diver's mouth. The second stage (also called 'demand valve') allows air to be delivered to the diver at ambient pressure when the diver breathes in (i.e. 'on demand') and that valve is inside a casing with a mouthpiece that the diver places in his mouth.
 * An 'automat' is a vending machine (see the article you linked) - I know of no use of the word in a diving context.
 * I agree that many of these articles need to be tidied up. But read the articles I linked on diving cylinders and regulators. I think you'll find all the information in there (somewhere).
 * There is an hose connection to both the BCD and the drysuit. The air supplied in each case is vented on ascent and is not really reusable, other than in absolutely dire emergency. We used to teach how to breathe from a BCD or ABLJ, but the risk of microbial infection from organisms growing inside the BCD made training inadvisable. --RexxS (talk) 22:23, 8 January 2010 (UTC)


 * made this image File:Diving cilinder schematic.JPG
 * If there are any mistakes, ... let me know
 * 81.243.183.37 (talk) 16:03, 9 January 2010 (UTC)


 * Thanks for the schematic. There are a few things that you could improve on the legend:
 * 1 = Breathing gas cylinder
 * 3 = Pillar valve knob
 * 4 = Regulator first stage
 * 5 = Primary second stage
 * 6 = Submersible pressure gauge
 * 7 = Secondary second stage (octopus)
 * 8 = BCD hose
 * A isn't needed (already labelled 4)
 * B is wrong and not needed (second stages are 5 and 7)


 * And on the image:
 * The first stage is larger and is fitted at 90 degrees to the pillar valve - look at File:Diving regulator DIN first stage.jpg and File:Pillar valve DIN 232.jpg for close-ups


 * Do you use Inkscape or another vector graphics program? Any image is much better than none, but an .svg would allow others to modify (and translate into other languages) much easier.
 * When you decide on the size of the thumbnail on the page, keep in mind that the page may be printed out, so the image is most useful if it can be read. In this case I'd recommend 400px or thereabouts.
 * Finally, wouldn't the schematic be more appropriate here at 'Scuba set', rather than using it at 'Diving cylinder' (which of course is only a part of the set). Hope that helps. --RexxS (talk) 17:36, 9 January 2010 (UTC)

Quality rating
Per User:Sbharris in this edit, it is not a stub and needs re-rating. I suggest the options are: I would say that it meets C class, but does it achieve B?
 * B: Readers are not left wanting, although the content may not be complete enough to satisfy a serious student or researcher
 * C: Useful to a casual reader, but would not provide a complete picture for even a moderately detailed study.

Detailed B-class criteria state:

Peter (Southwood) (talk): 09:31, 17 June 2012 (UTC)
 * 1 Quite a lot of uncited statements, some dubious, but now mostly tagged. Peter (Southwood) (talk): 10:37, 17 June 2012 (UTC)
 * Somewhat improved by now, but still some way to go. Peter (Southwood) (talk): 12:24, 18 June 2012 (UTC)
 * 2 Complies for coverage, bit shaky on accuracy in several places.Peter (Southwood) (talk): 10:37, 17 June 2012 (UTC)


 * 3 Looks OK Peter (Southwood) (talk): 10:37, 17 June 2012 (UTC)
 * Now better.Peter (Southwood) (talk): 12:24, 18 June 2012 (UTC)
 * 4 Can use some work, but not too bad. Good enough? Peter (Southwood) (talk): 10:37, 17 June 2012 (UTC)
 * Better than it was I hope. Always room for improvement, but I think good enough as it stands.Peter (Southwood) (talk): 12:24, 18 June 2012 (UTC)
 * 5 Seems adequate to me. Peter (Southwood) (talk): 10:37, 17 June 2012 (UTC)


 * 6 Looks OK to me. Certainly not over-technical in general. Peter (Southwood) (talk): 10:37, 17 June 2012 (UTC)

Overall I think it needs more work for B class. I will temporarily uprate to C. Input requested. Peter (Southwood) (talk): 10:37, 17 June 2012 (UTC)


 * It's certainly C-class - see WikiProject Scuba diving/Assessment, but the lack of references for many sections and multiple cn tags leave it short of B-class because of B1. It's well on its way against criteria B2-B6, and it may be that as more references are found the structure could be improved and other supporting materials added. This is, of course, an overview article and a balance needs to be struck between summarising articles such as Diving regulator, Diving cylinder, Rebreather, etc. and leaving it to the reader to visit those articles for the detail. --RexxS (talk) 12:56, 17 June 2012 (UTC)
 * It may be up to B by now. There is a citation needed for the last paragraph of the Rebreather section which eludes me, and that paragraph could be more elegantly phrased. Also a collection of unreferenced trivia and a small number of fairly uncontroversial points that would be better properly referenced. Peter (Southwood) (talk): 12:24, 18 June 2012 (UTC)

Still short on citations, &bull; &bull; &bull; Peter (Southwood) (talk): 15:14, 16 December 2016 (UTC)

Merger proposal
(Discussion copied from Talk:Rebreather)

I suggest that Diffuser (breathing set part) should be merged into this article as for most purposes it is a part of the structure of a diving rebreather and is hardly ever found on open circuit diving equipment. &bull; &bull; &bull; Peter (Southwood) (talk): 17:19, 1 March 2017 (UTC)
 * I think that we might have to follow the sources here, . Although I agree that Rebreather would be the obvious choice to us, at least two of the four sources in Diffuser (breathing set part) discuss the use of specialised diffusers in conjunction with open-circuit scuba. That indicates to me that we ought to also consider the possibility of merging Diffuser into Scuba set, where all four sources would be relevant. What do others think? --RexxS (talk) 20:33, 1 March 2017 (UTC)
 * Good point . I quite agree to merging any parts that are useful into the appropriate articles. My objection to the current article is that it is a subset of diffusers that just happen to be used in diving equipment, and a subset of component parts of diving equipment that happen to be diffusers. This is not a particularly notable way of distinguishing between diffusers, and unlikely to become a significant article anytime soon. We may as well have an article on bolts used in the construction industry. I would be quite happy with merging into a more inclusive destination. I have not heard of diffusers used on SSDE, so scuba set may well be the best place available. I will revise the notices accordingly. &bull; &bull; &bull; (Peter (Southwood) (talk): 06:47, 2 March 2017 (UTC)
 * Good point . I quite agree to merging any parts that are useful into the appropriate articles. My objection to the current article is that it is a subset of diffusers that just happen to be used in diving equipment, and a subset of component parts of diving equipment that happen to be diffusers. This is not a particularly notable way of distinguishing between diffusers, and unlikely to become a significant article anytime soon. We may as well have an article on bolts used in the construction industry. I would be quite happy with merging into a more inclusive destination. I have not heard of diffusers used on SSDE, so scuba set may well be the best place available. I will revise the notices accordingly. &bull; &bull; &bull; (Peter (Southwood) (talk): 06:47, 2 March 2017 (UTC)
 * Good point . I quite agree to merging any parts that are useful into the appropriate articles. My objection to the current article is that it is a subset of diffusers that just happen to be used in diving equipment, and a subset of component parts of diving equipment that happen to be diffusers. This is not a particularly notable way of distinguishing between diffusers, and unlikely to become a significant article anytime soon. We may as well have an article on bolts used in the construction industry. I would be quite happy with merging into a more inclusive destination. I have not heard of diffusers used on SSDE, so scuba set may well be the best place available. I will revise the notices accordingly. &bull; &bull; &bull; (Peter (Southwood) (talk): 06:47, 2 March 2017 (UTC)

(end copied discussion - continue from here) Notices revised. &bull; &bull; &bull; Peter (Southwood) (talk): 12:49, 2 March 2017 (UTC)

Breathing gasses section
All,

Reading through this, it feels pretty comprehensive on the mechanical side, but the breathing gas piece feels a bit cursory by comparison, especially since the rest of the article makes reference to using pure oxygen, trimix and other 'exotics' ... so spending a bit of space on what people breathing and how it has evolved feels as important as the equivalent technical side. I've had a go at a replacement block for that section, but since this is a high importance page, and I'd need to suss out sourcing and links before putting it in, I've put proposed text below rather than directly editing the article at this stage. Its longer, but not more so than the other sections. I've tried to give some basic information on what factors matter, then how they have impacted recreational, technical and open & closed circuit over time. Thoughts? Greg (talk) 20:48, 8 July 2017 (UTC)

Proposed text :-

Whilst common, compressed air is not the only gas used in scuba sets. As depth increases the pressure of each component of the gas (known as the partial pressure of that gas) also rises, bringing five effects that need managing, and may justify the use of different breathing gasses in the scuba set to safely support the goals of the dive effectively.
 * If the partial pressure of oxygen rises above 1.6 Bar, there is a risk of a dangerous toxic reaction that cause convulsions, which in turn makes it improbable that the breathing apparatus will stay in the mouth
 * If the proportion of oxygen in the breathing gas is reduced to avoid the toxic effects that come from depth, it may no longer be safely breathable at shallow depths, with 16% at the surface taken as a minimum below which there is an excessive risk
 * Inert gases, such as the nitrogen that makes up 79% of air, dissolve in the body at a rate the depend their partial pressures, and vary for different tissues. As the diver surfaces this dissolved gas needs to leave the body, and surfacing too fast risks this dissolved gas forming bubbles in the body, producing Decompression Sickness, also known as the bends
 * Too high a partial pressure of nitrogen creates nitrogen narcosis which has symptoms similar to drunkenness, that reduce the abilities of the diver to manage their dive safely. The severity of this effect varies between divers, though if using air, many experience some mild symptoms below 30m and it is often severe enough that most agencies today limit its use below 40-45m
 * Carbon dioxide forms a tiny part of normal air, so the dangerous effects of an excess (called hypercapnia) are not experienced. But, where the breathing gas is recycled as it is in closed circuit sets, the carbon dioxide needs to be removed

Early closed circuit scuba sets used gasses with high percentages of oxygen which restricted the depth at which they could be used. When open circuit scuba was invented it used compressed and filtered air which was the only economically available gas, but did allow use deeper than possible with closed circuit scuba of the time. Care was still required, particularly to avoid carbon monoxide from engine exhausts being drawn into the air inlet, as the increased partial pressures at depth makes even very small amounts of carbon monoxide dangerous.

Within recreational open circuit diving the main limit experienced is from the dissolved inert gases. To help extend such dives, some divers began using breathing gas mixtures known as Nitrox that replace some of the nitrogen with oxygen. But, using Nitrox does increase the risk of oxygen toxicity at depth, so using Nitrox also means the diver needs to be closely aware of the maximum operating depth (MOD) for their breathing gas. Concerns about these risks meant initial adoption was fairly slow. But by the late 1990s the use of Nitrox in recreational diving became widely spread, with Nitrox course become some of the most common post Open Water qualifications. Typical Nitrox mixes used recreationally are EAN32 (32% oxygen), and EAN36 (36% oxygen)

For diving deeper than recreational levels, the level of nitrogen narcosis can be reduced by using some helium in the breathing gas - a mix known as Trimix if there is still some nitrogen, or Heliox it is just a mix of oxygen and helium. In open circuit scuba the cost of this helium can become a material part of the overall costs. In addition, the level of oxygen in breathing gasses required at the various depths may range from a ‘bottom mix’ that has too little oxygen to be breathable on the surface (known as hypoxic mixes), through to high levels used to reduce the decompression time taken for inert gasses to leave the body, but which have quite shallow Maximum Operating Depths. In open circuit diving these high oxygen percentage decompression / shallow mixes are in separate independent scuba sets, known as stages, that the diver carries along with their main set. Safe use of these types of gas mixes is one of the reasons that substantially more experience, skill and training is required to be able to safely conduct technical dives, whether open or closed circuit.

The mix of breathing gas in a closed circuit (rebreather) scuba set is not fixed as it is in open circuit. The system is filled from a cylinder of gas, known as the diluent, that is similar to the found in open circuit systems used at a similar depth. But, whilst some diluent needs to be added to offset pressure as depth increases, unlike open circuit the bulk of this gas is recycled. As the diver breathes, the carbon dioxide they exhale is removed, and the oxygen they have used is replaced from a separate pure oxygen cylinder. Early rebreathers used a continuous slow feed of oxygen that approximately matched the rate the resting usage rate of the diver. If they had to work harder they could manually add more. Modern closed circuit rebreather scuba sets maintain a set partial pressure of oxygen automatically, though some divers still prefer to use a manual system. A diver using a rebreather for a technical dive would typically still carry one or more independent scuba sets (stages) for safety in the event that there is an issue with their rebreather.


 * , There is a separate article on breathing gas linked from the section. Most of it is about breathing gases for diving, which includes scuba, and goes into much more detail than this article, which is about scuba sets, which are the equipment used to deliver the breathing gas. When a scuba set is empty, it does nor stop being a scuba set, so the gas it contains is peripheral information. Do you think that it is really useful to expand this article to include that peripheral information, when a more extensive coverage is a click away? It is necessary to mention the breathing gas, as it is necessary to the function of the equipment, and to understanding this function, but the details of the gases used are beyond the scope of the article. Whenever there is sufficient information to justify a specific article, it is split off and replaced by a link and a summary, to keep the original article at a readable and manageable length. You are welcome to provide reasons why you may think I am mistaken in this case.  &bull; &bull; &bull; Peter (Southwood) (talk): 07:42, 9 July 2017 (UTC)


 * It's a fair point. But if the section is worth including then I still think it a bit unbalanced to omit the range of fairly commonly used Scuba gasses in favour of extra detail on recreational Nitrox.  Maybe a compromise would be something like "Until nitrox, which contains more oxygen than air, was widely accepted in the late 1990s, almost all recreational scuba used simple compressed and filtered air. Other gas mixtures, typically used for deeper dives, may substitute helium for some or all of the nitrogen (called trimix, or heliox if there is no nitrogen), or use lower proportions of oxygen than that found in air.  In these situations divers often carry separate scuba sets, called stages, with gas mixtures with higher levels of oxygen that are primarily used to reduce decompression time.  These gas mixes allow longer dives, better management of the risks of decompression sickness, oxygen toxicity or lack of oxygen (hypoxia), and the severity of nitrogen narcosis.  Closed circuit scuba sets have a gas mix that is controlled dynamically to best optimise the mix for the actual depth at that point in time." Greg (talk) 08:06, 9 July 2017 (UTC)


 * , Nice summary. It should not take long to reference it, then go ahead and make the change. &bull; &bull; &bull; Peter (Southwood) (talk): 05:40, 10 July 2017 (UTC)


 * Your more comprehensive explanation above may be worth considering for addition to the Breathing gas article as an introduction to the section on breathing gases for diving and other hyperbaric use. Some work would be necessary to blend it in with the existing content. &bull; &bull; &bull; Peter (Southwood) (talk): 05:53, 10 July 2017 (UTC)


 * Done inc, references which now covers all of the items in the 'See also' piece in the same section, so I took that out. Also sorted citation for the adoption of Nitrox for recreational use which was missing in the original.  Will have a look at the intro in the Breathing gas article when I get a chance, but prob not for a week or two. Greg (talk) 08:23, 10 July 2017 (UTC)

NOT reverting unrelated, GOOD editions while correcting bad ones!
Okay, for some reason you guys think that when you repair damage, such as breaking links, you have to go in and undo improvements that were made at about the same time as the damage. Fine, undo the damage; that makes sense. But while you do it, it's your responsibility to make ONLY those fixes; not to undo changes that are actually GOOD to go along with them. Why can't you just make your changes that fix broken things like links while leaving actual improvements alone?

I already explained on your talk pages why those other changes should exist. So be responsible enough to make your repairs and leave the unrelated edits--improvements as I demonstrated in your talk pages, including orders by MOS:HYPHEN}] and [[WP:TENSE--alone.

97.117.54.205 (talk) 17:28, 26 August 2017 (UTC)


 * Just how long have you been editing on Wikipedia? I ask so that I have a better idea of what I should expect you to know, and so that I do not react too strongly to someone who has not been here long enough to learn the ropes. Cheers, &bull; &bull; &bull; Peter (Southwood) (talk): 17:42, 26 August 2017 (UTC)
 * Reply to 97.117.54.205/185: You made over 20 changes in a single edit. That causes problems for other editors reviewing the changes. In one paragraph, you changed the tense describing a 1990s prototype from past to present. I disagree with that as there is no evidence that the prototype still exists 25 years later. In the same paragraph you also broke the link to Diving regulator, so I reverted those changes to that paragraph alone. I have no problem with your other changes. You have now reverted to your version, breaking the link, three more times. The onus is on you to make a case for your changes when challenged, not to edit-war to try to force your broken version back into the article. --RexxS (talk) 18:03, 26 August 2017 (UTC)
 * Reply to 97.117.54.205/185: You made over 20 changes in a single edit. That causes problems for other editors reviewing the changes. In one paragraph, you changed the tense describing a 1990s prototype from past to present. I disagree with that as there is no evidence that the prototype still exists 25 years later. In the same paragraph you also broke the link to Diving regulator, so I reverted those changes to that paragraph alone. I have no problem with your other changes. You have now reverted to your version, breaking the link, three more times. The onus is on you to make a case for your changes when challenged, not to edit-war to try to force your broken version back into the article. --RexxS (talk) 18:03, 26 August 2017 (UTC)


 * I see that the individual improvements have been made back now, so that's good, but I still have these concerns for you to address:
 * I've been here on the site for a long time, but some people--like you and rexxs--still seem to think that you have no responsibility to leave unrelated edits alone while reverting the things that you have your specific gripes about. So I'm doing that same thing in reverse: undoing all the edits, and then having you redo ONLY those edits that you have concerns with. Why can't you just leave the other ones alone like you're supposed to do?
 * I refer you to WP:POINT - Do not disrupt Wikipedia to make a point.
 * If you have been here for a long time you should know better than to edit war. If you were new I would have more sympathy. As you claim to have been editing here for a long time, you will be held responsible for any disruptive and uncivil behaviour and must take the consequences. You should also know that all caps (shouting) is considered impolite. &bull; &bull; &bull; Peter (Southwood) (talk): 19:48, 26 August 2017 (UTC)

, where do you keep getting the oddball idea that I was supposedly editing the 'Pedia to "make a point"? What supposed "point" could I have been trying to make? And why is it that you put all the blame on me for disruptive editing, when it was really rexx and YOU who kept on insisting that you destroy unrelated edits while making the ones that you really had the concern about? If you can destroy my good edits to revert yours back in, then why is it supposedly so "wrong" for me to destroy edits to redo my good edits? Why is it supposedly "my fault" that you and rexx can't have the decency to make ONLY the edits that you're really concerned about instead of throwing out ALL my edits in that session just because they were made by the editor who made the ones that you were concerned about? All-caps aren't shouting unless you do it for more than one word or term in a row. Let me show you what shouting is NOT: <--That. THIS IS AN EXAMPLE OF SHOUTING, THOUGH, BECAUSE IT'S A WHOLE STRING OF WORDS IN A ROW! You see the difference? When you do it with just one word or term at a time then all it is is just another form of EMPHASIS when you don't feel like using Italics or boldness.

Now before we reply here, let's just go down to the bottom, because you may have already answered at least one of my questions down there.

97.117.54.205 (talk) 05:14, 27 August 2017 (UTC)


 * , I see that the individual improvements have been made back now, so that's good, but I still have these concerns for you to address:
 * I wasn't trying to force my broken version back into the article. I was just using the same tactic you were using to redo the GOOD edits, which happened to redo the bad ones, which is the same irresponsible tactic you were using on me to undo the bad edits, so that you can see that you were making the mistake of ruining good edits while fixing bad ones. So if you have no problem with my other changes (adding the needed hyphens and removing the stray quotation marks), then why do you keep reverting them along with your reversion of the broken links? How do you figure that the onus is not on you to make the repairs and then leave the edits you have no problem with ALONE?


 * And then where did you get the idea to report me even though I had NOT made any new edits to the article since the time that you said you would report me IF I did, which I had not done?


 * 97.117.54.205 (talk) 19:17, 26 August 2017 (UTC)


 * As I mentioned above, you reap the consequences of your actions. When you make a series of edits of which the overall balance is bad, you can reasonably expect them to be reverted wholesale. The other editors are not here to carefully salvage those parts of your edits which might be slight improvements. They too are volunteers, and must make a reasoned decision as to whether the time spent is worthwhile. Fixing damage comes first. Minor adjustments to spelling and grammar may be worthwhile in the long run, and are generally welcome, but are not urgent, and do not justify disrupting the work of other editors who may have several options of better things to do waiting in line for their attention. When you add uncivil behaviour it does not improve your case.&bull; &bull; &bull; Peter (Southwood) (talk): 19:48, 26 August 2017 (UTC)
 * One more thing, Please read and understand WP:VANDALISM before accusing other editors of vandalism. It has a specific meaning here and inappropriate use is not suffered gladly. &bull; &bull; &bull; Peter (Southwood) (talk): 21:32, 26 August 2017 (UTC)

Okay, Petey, I get that they might not want to go through and remake my edits for me. That's not what I was expecting. But reversions can be done without undoing everything from one editing session. Look: what you two reverted was more UNRELATED stuff (not shouting; just choosing that as my method of emphasis for that word) than it was of your real concern, the correcting of links. What would have been "so hard," according to you, about just retyping the capital letters to correct the links, which would not be the same thing as having to go back through and redoing my edits?

And how do you figure that my behavior of doing exactly what you two were doing--including unwanted changes in a reversion while adding my changes back, which IS what you two were doing--is supposedly any more "uncivil" for me to have done it than when you two did it?

And how about you tell rexxs to read the vandalism essay instead of me, since he was first at falsely accusing my posts to his page of being "vandalism" by saying "rvv" (a common wiki-dumb way of saying "re-vert vandalism") in his edit summaries of deleting my posts without having any decency to reply to them?

97.117.54.205 (talk) 05:14, 27 August 2017 (UTC)


 * The horse is dead, you can stop beating it now, pack up your soapbox and move on. If you are here to build the encyclopedia, do it, but I have wasted enough time on what now appears to be simple trolling behind the shelter of anonymity. If you want further discussion from me, move on to something more constructive and less about yourself. &bull; &bull; &bull; Peter (Southwood) (talk): 07:18, 27 August 2017 (UTC)


 * Been awhile since I've been able to contribute (apologies), but on the narrow point of present-vs-past tense Edit Wars, in reading the WP:TENSE, I find: Generally, do not use past tense except for deceased subjects, past events, and subjects that no longer meaningfully exist as such.  Given that the product in question dates from a quarter century ago and was known to have only been a prototype, not an ongoing product available still today for sale, I find the use of the past tense to be consistant with this guidance.  Therefore, Peter's editorial change to employ past tense is AFAIC correct and 100% appropriate.  -hh (talk) 20:54, 30 August 2017 (UTC)

Move discussion in progress
There is a move discussion in progress on Talk:Scuba which affects this page. Please participate on that page and not in this talk page section. Thank you. —RMCD bot 19:00, 16 October 2017 (UTC)

Merge proposal
I propose to merge Camstrap into Scuba set as it is a component part. There are other uses of similar items, but they are not the same and can best be mentioned where they are relevant. Current article Camstrap has been tagged as unsourced since December 2009, it is very small with little chance of much expansion. &middot; &middot; &middot; Peter (Southwood) (talk): 19:04, 3 November 2017 (UTC)
 * Discuss:
 * No objections, so will do the merge.&middot; &middot; &middot; Peter (Southwood) (talk): 07:07, 1 December 2017 (UTC)
 * ✅ &middot; &middot; &middot; Peter (Southwood) (talk): 07:34, 1 December 2017 (UTC)

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SCUBA
This is an acronym. SCUBA. It even says this in the article. 79.106.209.51 (talk) 23:50, 29 December 2022 (UTC)