High Pressure Plus Hydro?

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wxboy911

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Messages
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Location
New York
# of dives
25 - 49
So I dropped my Faber FX 80 off at the test facility last week. Few days later I get a call saying its done...When I go to pick it up the tech tells me it passed the "+" test. He went on to say that any tank with an REE number could get the "+". I never asked for the "+" figuring 3442psi was high enough.

Now onto the problem...the LDS wont fill it till they check with DOT and make sure getting a "+" on an HP tank is OK. Anyone ever run into this?
 
It sounds like the hydro guy doesn't know what he is doing. As far as I know a HP tank does not get a + rating. If that is the case, I think it is time to find someone else for hydro testing, if they don't know these things who knows what they are actually doing with your tanks.
 
Does the tank has a + next to the original hydro date?
Is the tank a DOT-3AA?
Or is the tank a Special Permit (next to the DOT it reads SP or E and then a number)?

If the tank did not have a + next to the original date it does not get a +.
If it has a "+", it most likely is a 3AA tank and not a Special Permit tank.

Most high pressure tanks are Special Permit (which do not get a +), but not all.

What is the stamped pressure of your tank?
 
Brought my wife's two HP80's into the LDS for a hydro last year. They sent them to the local hydro shop. Shop noted that one wouldn't require hydro for another 6 months and wanted to know whether to hold on the hydro - trying to save me money. I wanted them done at the same time so that I could get them done together in the future, so I told them to hydro both. Unfortunately it seems that by separating them, someone at the hydro shop screwed up and one came back with a + and one without. Pluses are not valid for exception tanks. Spoke to the LDS and they had a discussion with the hydro shop. So far I haven't had a problem getting it filled, but I do most of the fills myself. Same shop also broke an I valve on one of my ponies and substituted a straight thread medical O2 valve for my taper thread "I" post... Another discussion with the LDS and another teaching opportunity... I hear the operator in question is no longer employed..

Another Hydro shop up here was sold recently and it seems the new operator decided to not bother getting registered. They were caught using a stamp registered to a hydro company in another state. A different LDS that used their services ended up eating a lot of hydros.

Re the REL I am of the understanding that the reason it is found on newer tanks is that in the past operators tended not to bother looking it up and without it they can not calculate if the tank passes well enough to get a plus. Historically, the + goes back to WW2 when tanks were in short supply and DOT engineers took another look at their requirements and determined that it would be safe to over fill the normal tank by 10%. Thus immediately increasing the gas storage capacity of the country by 10% without making any new tanks. If anyone has a better/more detailed grasp of historical events concerning the Plus I would like to know more.
 
I had some Faber 3,180 + clyinders. Could fill to 3,500 psi with the ( + ), or 3,180 without it.
I have never seen a ( + ) in a 3,442 cylinder. I think the hydro shop messed up on your cylinders.

Jim Breslin
 
Brought my wife's two HP80's into the LDS for a hydro last year. They sent them to the local hydro shop. Shop noted that one wouldn't require hydro for another 6 months and wanted to know whether to hold on the hydro - trying to save me money. I wanted them done at the same time so that I could get them done together in the future, so I told them to hydro both. Unfortunately it seems that by separating them, someone at the hydro shop screwed up and one came back with a + and one without. Pluses are not valid for exception tanks. Spoke to the LDS and they had a discussion with the hydro shop. So far I haven't had a problem getting it filled, but I do most of the fills myself. Same shop also broke an I valve on one of my ponies and substituted a straight thread medical O2 valve for my taper thread "I" post... Another discussion with the LDS and another teaching opportunity... I hear the operator in question is no longer employed..

Another Hydro shop up here was sold recently and it seems the new operator decided to not bother getting registered. They were caught using a stamp registered to a hydro company in another state. A different LDS that used their services ended up eating a lot of hydros.

Re the REL I am of the understanding that the reason it is found on newer tanks is that in the past operators tended not to bother looking it up and without it they can not calculate if the tank passes well enough to get a plus. Historically, the + goes back to WW2 when tanks were in short supply and DOT engineers took another look at their requirements and determined that it would be safe to over fill the normal tank by 10%. Thus immediately increasing the gas storage capacity of the country by 10% without making any new tanks. If anyone has a better/more detailed grasp of historical events concerning the Plus I would like to know more.

You got the history right. It also saved on steel for makings weapons of war rather than more tanks.
 
Not DOT engineers, of course, but ICC. An awful lot of cylinders were making one-way trips then, so it made a lot of sense. After the war, the DOT analyzed results, and found there had been no reliability or safety problems at the higher pressure, so they decided to continue the "+".

There's an interesting postscript to this story that sort of explains why we are still stuck with the nutty and much misunderstood (though the gas industry seems to have no problem with it, the confusion is mostly in the dive world) "+" all these years later. The DOT has on several occasions made attempts to eliminate it, but never quite finished. Some years ago the plan was to, best I can recall, eliminate the plus and make the service pressure of the tanks that now qualify for the plus (3A and 3AA mostly, as far as we are concerned) 2/3s of the test pressure. That is to say, a 2400 psi LP tank which now has a test pressure of 3/5ths of its service pressure, or 4000 psi , and a "+" fill pressure of 2640 would have had a new service pressure of 2667 psi). Tanks would be stamped with both fill and test pressures, as Canadian and Euro tanks mostly are now.
After they'd been working on this for a few years someone pointed out that if they were going to come up with a new specification they really ought to go metric. So they switched to working on a metric version. After they'd been working on the metric version for a few more years someone noticed that the UN had a committee trying to come up with an international "model law" specification, and it occurred to the DOT that maybe it would make more sense to join in with that, rather than come up with another spec that would be good only in the US. Hence the new UN tanks. However, the gas industry turned out to be perfectly happy with things as they were, "+" and all, and not terribly excited about the new UN tanks (which are "high performance" designs, like current SP/exemption tanks), so the DOT allowed them to go on using the old DOT specs . So we still have the plus. I asked the DOT a few years ago if they were every likely to go back and do something about the plus, and was told it was very unlikely as it was pretty much a dead issue.


Historically, the + goes back to WW2 when tanks were in short supply and DOT engineers took another look at their requirements and determined that it would be safe to over fill the normal tank by 10%. Thus immediately increasing the gas storage capacity of the country by 10% without making any new tanks. If anyone has a better/more detailed grasp of historical events concerning the Plus I would like to know more.
 
3442 tanks are Exemption tanks and therefore should NOT be plus stamped. The hydro shop is obviously not trained very well.
 
https://www.shearwater.com/products/teric/

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