Comment about your "Comment": I AGREE WITH YOU ABOUT THE VIP STICKERS! Get to know your local air provider and ask if they would go for placing their VIP sticker in your logbook with a notation of the cylinder's serial number. They might be willing to accept that in lieu of one on the cylinder... I would. I am lucky enough to have my own compressors, but a quarry dive site that I frequent accepts my VIP records in my log instead of on my cylinders.SurfLung wrote:I have some questions and I'd sure appreciate some comments or suggestions...
Question #1 I have a couple of small tanks with tapered thread valves on them. I'm wondering if I can bring them for hydro testing with the valves loose and get them back that way? I'm trying to avoid somebody buggering them up any more than they are.
Answer #1: I have the same concerns, so I take my cylinders for testing with the opening covered with a plastic plug or tape so there will be no problems like you mention. You are right, don't give them a chance to screw up your valves!
Question #2 It has always rubbed me the wrong way that a DOT 5 year hydro test is good enough for every other industry but every year I have to subject my tanks to getting the valves wrenched off and on and then another ugly sticker pasted on them. Is the VIP program really necessary or just another profit string for the dive shop?
Answer #2: My reasoning for thinking that Scuba tanks need inspections more often is that they are used in and around the water and sometimes even filled in the water. Most non-Scuba high pressure cylinders don't have the plethora of opportunities for getting water into them. I have also seen instances where the fill operator carelessly dunked the valve or even dropped the fill hose end in the water before filling, giving an opportunity for small amounts of water to be introduced when the valve was opened and air flowed in. It doesn't take a whole lot to cause some corrosion. I service compressors for fire departments, dive shops and other breathing air uses, and it is not uncommon to find air filters that have not been changed often enough, with the result that moisture has entered their storage cylinders and/or breathing air tanks.
In another example of cylinders being around and in the water, I recently bought a nice 1955 Scott Hydropac with a 2 year old hydro date on the cylinder. Every component including the cylinder and valve looked almost perfect. Being very particular about the internal condition of my tanks, I pulled the valve. There was about 8 ounces of water inside, so I had to clean it up and dry it. Had I waited too long it probably would have corroded to an unsafe condition. I looked into a lot of cylinders during 31 years in the diving business, and the great majority of them were fine, but there were occasions that we found moisture that had already caused significant damage, and occasions where it was discovered early enough to save the cylinder
Question #3 (related to #2) I read about the Luxfer 6351 tanks and how there have been 12 ruptures since the early 70's attributed to SLC. That's 12 out of an awful lot of tanks over many years and several of those 12 were considered abused... Over filled, out-of-hydro, etc. I wonder what the rupture stats are for tanks used in other industries in comparison to the Scuba industry with their VIP. In other words, has VIP actually accomplished anything that hydro testing wasn't already doing?
Answer #3: Surflung, I hope you don't think that I am arguing with you or that I don't respect your views on the subject. I do want all of us to be as safe as possible. I base many of my thoughts about this on the experience of 31 years owning a dive shop, and the past 10 years still involved in the compressor and high pressure cylinder business. I'm not saying that I am an expert... there are many more knowledgeable on this subject than I... I just believe in doing this thing safely, because the consequences of a cylinder failure are so severe. I can't help but wonder how I would feel if I owned one of those 12 cylinders that failed... somebody did. I absolutely believe in carefully inspecting all aluminum cylinders thoroughly for neck cracks annually. Luxfer says their 6351's must be checked twice a year. Steels should be checked annually, or sooner if there is reason to believe moisture has had a chance to enter.
Comment: I like my tanks to look nice and I resent the VIP messing them up.
Pucker factor is off the charts in the above scenariocaptain wrote:To quote Luis,"Stories of aluminum tanks leaking from a crack during the filling process are not uncommon. Some I have heard first hand from people that were present. Having to stop a fill mid-track, close valves, disconnect a fill whip, and empty a tank leaking from a crack is an experience that would probably a life changing experience… It is an experience I totally want to avoid."
I also don't want to become a one man bomb disposal squad technician.
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