Talk:Diving cylinder

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12/14/06 Discussion regarding the phrase copied below:

A diving cylinder (the term which tends to be used by divers) or SCUBA tank (more often used colloquially by non-divers)

As a NOWI Certified Diver and a PADI Certified Diver for more than twenty-five years, I can attest to the fact that I have never heard an American diver or American Oceanographer refer to our "Dive Tanks" as anything other than "Tanks." Therefore, the author's statment as prefaced above in parenthesis may be not be valid.

In any case, the reference to "non-divers" seems a bit unnecessary and sounds more like personal opinion rather than an actual fact. I recently, reviewed my old dive manuals whereby, the official terminology used here in the USA is "Tank" and not "Cylinder." The only exception I found was at a PADI web site tonight. However, I noticed the date of birth on the registration page of the website is European I.e. day/month/year as opposed to American month/day/year. Therefore,the term cylinder would be more appropriate coming from European divers. There is also a dive master video on the NOWI website regarding equipment. The term tank is being frequently used by the dive master when referring to the breathing unit.

European divers would generally refer to them as "tanks" - the proper name being a "cylinder" however, its not used in general speaking. Perhaps non-english speakers translate as cylinder? —Preceding unsigned comment added by 89.168.72.84 (talk) 23:05, 9 December 2007 (UTC)

I have seen the same (idiotic) argumnet over the term skeg or fin on a surfboard and have heard some say that only a non-surfer would say skeg. I simply believe this type of commentary detracts from the article in general and is therefore, may not necessary.

PEACE (LCrockett 04:16, 15 December 2006 (UTC))hope I did this correctly :-(?

You don't have to indent paragraphs (screws things up if you do). Otherwise you did fine.

I get three times as many Google hits on scuba tank as scuba cylinder. But I do notice that makers and engineers tend to call them cylinders. Perhaps this filters down to those who want to sound like the people who make (and service and hydrotest) the stuff, rather than just use it. SBHarris 08:23, 15 December 2006 (UTC)

Should Diving tank be added as a redirect to this article? --ArmadilloFromHellGateBridge 08:36, 15 December 2006 (UTC)

Yes, I think so, and have done so. Along the way I fixed the definitions so that I think everyone will be happy and satisfied. "Gas cylinder" is the generic term used by engineers and the ACGA people who use all kinds of sizes of compressed gas containers, not just the ones for scuba. Even the big H cylinders get called tanks by the non-cognoscenti, but never by people who work on them for a living. The same kind of distinction carries over to scuba. SBHarris 18:27, 15 December 2006 (UTC)

[edit] Diving Oxygen

"Breathing industrial compressed gases can be lethal because the high pressure increases the effect of any impurities in them.". I breath welding oxygen on a regular basis and so do a lot of other people. My research says it's the same oxygen used for both applications. Maybe that should be clarified. 142.165.246.187 16:13, 10 February 2007 (UTC)

I would wish to take issue that welding and breathing oxygen can be regarded as the same product. In the UK, USA and Europe there are both civilian and military specifications for welding oxygen and for diving quality oxygen (and medical oxygen). I would suggest that you could safely use diving oxygen and medical oxygen, if you wished, for welding but it would not be sensible to do so as these products are more expensive than welding oxygen. Likewise, you could use industrial grade oxygen (welding oxygen) for diving, however it is not sold (in the UK and Europe) as a breathing gas; and that it would be safer to use one that is sold for that purpose. Perhaps, that partially answers your point.Pyrotec 18:29, 10 February 2007 (UTC)

My anecdotal experience comes from talking to someone who worked for BOC (British Oxygen Company) some years ago. He maintained that all of the oxygen sold came from the same source, i.e. there was only only one process used. The only exception being "Aviation grade" oxygen which had an extra stage of processing to remove any remaining water vapour because of the low temperatures that this oxygen may be exposed to. So medical, breathing and welding oxygen all came out of the same pipe. The catch was that BOC rented large cylinders to the end-user to hold the oxygen; when empty, these would simply be swapped for a full one. There was no procedure for ensuring that the cylinder was clean for customers who purchased welding oxygen, while the "higher" grades had the cylinders cleaned regularly. All of this seems to make commercial sense to me, so I have no reason to dispute his claims. Bottom line: you have a good chance of getting the same oxygen when breathing "welding grade", but no guarantees. RexxS (talk) 20:09, 6 January 2008 (UTC)

"The pipe bit" is not the whole story; as you say an important part of the filling process is ensuring that the cylinder is clean before it is filled. Any hospital or dive shop that "plugs" a patient or diver into a cylinder of welding grade oxygen is going to get a large legal bill if someone suffers as a consequence. If its a proper medical or diving cylinder, then BOC or its competitors carry the consequences of "dirty" product being supplied. Pyrotec (talk) 20:26, 6 January 2008 (UTC)

[edit] Gas quantity calculations

To calculate the quantity of gas:

 quantity of gas = volume x pressure

But:

3 litres * 200 bar = 60 kilojoules

Should the article clear this up? Also we might want to include some mention of the energy content (compressed air) of scuba tanks. —Preceding unsigned comment added by Glueball (talk • contribs) 11:55, 12 July 2007(UTC)

The formula only works in metric units - it's just Boyle's Law (and subject to the same limitations). Should be

"Volume of gas at atmospheric pressure = (cylinder volume) x (cylinder pressure) / (atmospheric pressure)"

I'll change it. And it would be of interest to show the energy stored in a cylinder - maybe with some comparisons to TNT, etc.? RexxS (talk) 20:29, 6 January 2008 (UTC)

[edit] Breathing Time

The formula and example are wrong, imho. They miss the point that ambient pressure should include the contribution of the weight of air above the water. In metric terms, you need to add 1 bar (or atmosphere - I know they're strictly not the same). The current formula leads to the conclusion that you can breathe off the cylinder for an infinite time at a depth of 0 metres! I would suggest:

AP = D * g * rho + atmospheric pressure

in proper units. However, gravity and water density are near constant compared to other variables, so this approximates to:

AP = D / 10 + 1

for all practical purposes. Remember that analogue depth gauges and analogue pressure gauges have errors both in linearity and readability, so there's little point in trying for absolute accuracy here when other variables can easily be out by 5% or more. Not forgetting of course that "depth gauges" work by measuring ambient pressure anyway, so correcting for water pressure is pointless as you really ought to correct the depth read by the same factor in the opposite direction - unless somebody has invented a dive computer that knows if it's diving in fresh or salt water. And of course, the biggest variable is breathing rate, which is difficult to keep within +/- 10% even for the most experienced divers.

Finally, there's no point in using the term (CP-AP) when CP is much greater than AP in all practical circumstances. If the purpose of this section is an illustration of how dives may be planned (rather than a sterile demonstration of how long before a cylinder becomes unusable), may I suggest that (CP-RP), where RP is the reserve pressure, would give more real-life information to the beginner and non-diver alike?

RexxS (talk) 21:40, 6 January 2008 (UTC)