SparticleBrane
Contributor
You pretty much don't have the slightest idea what you're talking about.
Tapered thread DIN valve?
- Thread starter Anticarus
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Faber Dude
Guest
Ok, there's no need for rude comments here! If you disagree with me, simply present your argument. Don't be childish and tell me that my remark is "a crock-o-shiite."
captain
Contributor
1. A steel cylinder has an indefinite life with proper care. Keep fire away from the outside and water away from the inside. I have several 50+ year old 1/2" thread tanks that I use. They will out live me and probably every one here if the next owner takes care of them.
2. A yoke valve is a yoke valve, doesn't matter how it screws into the tank. If the valve operates easily and doesn't leak, use it. A valve is about the most reliable piece of scuba equipment there is. Of course they aren't fool proof as some fools forget to open them before jumping in. Do replace the bust disc with new one.
Scared Silly
Contributor
You might also want to do the same - present your argument rather making statements such as:
Faber Dude:
Which some would consider a crock-of-excrement. As several have posted, there are steel cylinders out there that were made well before you and probably most people on this board could wipe their own butt, myself included. Old does not mean unusable.
FD, there some folks on this board that really have a huge amount of knowledge when it comes equipment. If you really want to learn sit back and read posts from folks like DA Aquamaster, LuisH, da Captain, OxyHacker, and others. These guys post regularly and are always happy to share their knowledge.
Oh yeah, just because your not paranoid does not mean that they are not after you
.
I concur completely SS! I feel lucky that ScubaBoard has such a wealth of knowledge here with our members. There are so many members that have so much to share, though sometimes things come across a little harsh on the internet (especially when you are new here and just getting your feet wet). Unless you are 100% sure your answer is correct it shouldn't be posted as fact; we wouldn't want to propagate any myths or anything that we've been told that wasn't quite correct.
We're not in the PUB boys, play nice and be friendly.
:kiss2:
Next Guinness is on me (who's going to ITK?)!
Faber Dude
Guest
I agree with Ann Marie on the "harsh" comment. I got this nice "welcome to SB" warm and fuzzy feel when I signed up. Suddenly, soon as I open my mouth to express an OPINION, I get the whole "******* off, newbie!!!" treatment!
BTW, I do have reasons that back up my argument...
I agree completely that steel cylinders will last for centuries if they fall into the right hands. Theoretically, any cylinder can last you your entire diving career. However, you could also say that if you were to manufacture a cylinder, place a titanium cap on it, and throw it into a dark closet, it will out-live God! Sounds a bit crazy, but that is simply a slightly extreme form of what you guys are saying here. A new cylinder that is never used will still be "new" forty years later. But the "typical" SCUBA cylinder will get used quite a bit over forty years. Age is simply a rough estimate of how many uses a cylinder has been through. Every time it gets filled, used, and filled again, the metal gets stressed. After so many thousands of times a steel cylinder endures 2200-2400 pounds of added pressure, the metal will fatigue. That is not a myth, that is FACT! Otherwise, why would hydrostatic tests even be necessary? EVENTUALLY, all cylinders will fail. You COULD say that the best way to care for a cylinder is not to use it but... yeah... that's ridiculous!
It is also true that different cylinders are made differently. Some are simply more well-made than others (and will last longer). For instance, I've popped open about a hundred Fabers that were over a decade old that were prestine inside (phosphatized interior coating... I guess it works pretty well)!! However, I have also seen the XS SCUBA hp steels (the ones we sell at sport chalet) that need a tumble even before they fall off the truck!! So, in that regard, you could say that they "just don't make 'em like they used to."
Quick note: Yes, I do work at Sport Chalet. But I am also an AAUS Scientific diver... I hope you will take that for what it's worth. SS, along with the mentioned "SB veterans"... you have my respect, so long as I have yours. Remember, it is not how much knowledge you have, it is how you present it that counts!
Dive well,
FD
BTW, I do have reasons that back up my argument...
I agree completely that steel cylinders will last for centuries if they fall into the right hands. Theoretically, any cylinder can last you your entire diving career. However, you could also say that if you were to manufacture a cylinder, place a titanium cap on it, and throw it into a dark closet, it will out-live God! Sounds a bit crazy, but that is simply a slightly extreme form of what you guys are saying here. A new cylinder that is never used will still be "new" forty years later. But the "typical" SCUBA cylinder will get used quite a bit over forty years. Age is simply a rough estimate of how many uses a cylinder has been through. Every time it gets filled, used, and filled again, the metal gets stressed. After so many thousands of times a steel cylinder endures 2200-2400 pounds of added pressure, the metal will fatigue. That is not a myth, that is FACT! Otherwise, why would hydrostatic tests even be necessary? EVENTUALLY, all cylinders will fail. You COULD say that the best way to care for a cylinder is not to use it but... yeah... that's ridiculous!
It is also true that different cylinders are made differently. Some are simply more well-made than others (and will last longer). For instance, I've popped open about a hundred Fabers that were over a decade old that were prestine inside (phosphatized interior coating... I guess it works pretty well)!! However, I have also seen the XS SCUBA hp steels (the ones we sell at sport chalet) that need a tumble even before they fall off the truck!! So, in that regard, you could say that they "just don't make 'em like they used to."
Quick note: Yes, I do work at Sport Chalet. But I am also an AAUS Scientific diver... I hope you will take that for what it's worth. SS, along with the mentioned "SB veterans"... you have my respect, so long as I have yours. Remember, it is not how much knowledge you have, it is how you present it that counts!
Dive well,
FD
FD
Welcome to ScubaBoard.
As you mentioned, it is important how we post information, but IMHO, it is even more important that we don't spread wrong information.
Your statements on your last post about metal fatigue are incorrect. The number of pressure cycles a tank receive even if they are filled daily are very small and the design stress level (if they are not overfilled) is low enough that a cylinder will endure many... many decades. This is not just theoretical these are also facts based on observations of cylinders that are many decades old.
The stress cycles are also none reversing (the stress is only positive) so the fatigue life is much higher than in reversing loads.
You ought to read Pete Johnson (Gilldiver) post number 24 on the thread below:
http://www.scubaboard.com/forums/tanks-valves-bands/277122-life-aluminum-age-cycles-based.html
What kills most tanks is corrosion, not pressure cycles. Heat, as in a fire, will also destroy the heat treatment of most cylinder alloys. This is the case for aluminum or steel, but aluminum is affected by much lower temperatures.
The reason hydro test are performed is because it is an easy inexpensive way of doing non-destructive testing that indirectly checks material condition and material stress (as a function of deformation/ strain). Since corrosion (a.k.a. rust in the case of steel) is the major destructive cause of steel cylinders, visual inspections can be in many ways more important than hydro tests.
BTW, since we are posting credentials:
I stated working in a dive shop almost 40 years ago. I did regulator repairs, tank inspections, and hydro tests shortly after I started at that shop. Since then I have helped on many other shops, most recently only as a technical consultant.
I have over 30 years of engineering experience with a couple of engineering degrees, one in mechanical engineering. In part of my career, I have design many pressure vessels including ASME code pressure cylinders.
Only recently I took some of PSI/PCI tank inspection certification courses (as I mentioned I have been doing VIP for almost 40 years), in exchange for some engineering consulting I have done for PSI.
If you read through my post, I hope you can notice that I always try to make it clear when I am posting my opinion versus a fact. If I am posting a fact (unless I make a mistake, which I have done and I am sure to do again) it means that I can back it up with printed information or my own calculations. In some of my posts I try to include references when it is convenient.
Welcome to ScubaBoard.
As you mentioned, it is important how we post information, but IMHO, it is even more important that we don't spread wrong information.
Your statements on your last post about metal fatigue are incorrect. The number of pressure cycles a tank receive even if they are filled daily are very small and the design stress level (if they are not overfilled) is low enough that a cylinder will endure many... many decades. This is not just theoretical these are also facts based on observations of cylinders that are many decades old.
The stress cycles are also none reversing (the stress is only positive) so the fatigue life is much higher than in reversing loads.
You ought to read Pete Johnson (Gilldiver) post number 24 on the thread below:
http://www.scubaboard.com/forums/tanks-valves-bands/277122-life-aluminum-age-cycles-based.html
What kills most tanks is corrosion, not pressure cycles. Heat, as in a fire, will also destroy the heat treatment of most cylinder alloys. This is the case for aluminum or steel, but aluminum is affected by much lower temperatures.
The reason hydro test are performed is because it is an easy inexpensive way of doing non-destructive testing that indirectly checks material condition and material stress (as a function of deformation/ strain). Since corrosion (a.k.a. rust in the case of steel) is the major destructive cause of steel cylinders, visual inspections can be in many ways more important than hydro tests.
BTW, since we are posting credentials:
I stated working in a dive shop almost 40 years ago. I did regulator repairs, tank inspections, and hydro tests shortly after I started at that shop. Since then I have helped on many other shops, most recently only as a technical consultant.
I have over 30 years of engineering experience with a couple of engineering degrees, one in mechanical engineering. In part of my career, I have design many pressure vessels including ASME code pressure cylinders.
Only recently I took some of PSI/PCI tank inspection certification courses (as I mentioned I have been doing VIP for almost 40 years), in exchange for some engineering consulting I have done for PSI.
If you read through my post, I hope you can notice that I always try to make it clear when I am posting my opinion versus a fact. If I am posting a fact (unless I make a mistake, which I have done and I am sure to do again) it means that I can back it up with printed information or my own calculations. In some of my posts I try to include references when it is convenient.
Last edited:
Rick Christ
Contributor
Here you go again,
1. What codes are you referring to?
2. a Din valve has a higher burst disk then the old 2250 psi, you can not put a wrong pressure disk on a cylinder per "code"
3. These European cylinders, Do they have DOT stampings on them? If not, they can only be hydroed by a DOT retester if the cylinders are leaving the country. The cylinders cannot be refilled in this country unless they are leaving the country, if they are not a DOT cylinder.
A DOT retester could hydrotest a piece of pipe with a cap on one end and a reducer on the other and tell you what the elastic expansion and permanent expansion was. The DOT only can control how it is transported while filled (and somewhat how it is stamped).
Hydrotesting of non DOT stamped items is a common engineering practice.
Hydrotesting of non DOT stamped items is a common engineering practice.
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