How long does a steel tank usually retain its + rating in hydro?

[drummerc]

I'm considering buying some twin lp50s for shore diving (have twinned HP 100s but they're not light). As far as gas, they're supposedly 50cft at 2640 which includes the + stamp. That's plenty for a single dive for me, but got me thinking about if I were to buy older tanks or keep new ones for a long time, if they'd likely lose their + rating at some point in the future and if so, how long if kept in good condition until they usually no longer earn it in hydro? Also, it I were to find some older tanks that were originally + rated, but hadn't received the stamp in the last cycle or two or something, would most shops have any issue trying to get the + rating back, or once they fail to stamp + is that it for future hydros/fills? The loss in gas capacity wouldn't necessarily be a deal-breaker for me, I would just prefer to know what I'm getting into beforehand since the rated volume seems to rely on this stamp.

Also, if I were to use a transfil whip to top up the (mostly empty after first dive) LP50 tanks from my (full) HP100 doubles, it looks like I could probably close the manifold on the lp50s and juice the first tank up into the 2800s if I have 850+psi left, and then the second to a bit less, and then open the manifold to equalize them, ending something near 2640 or even over if my first dive is shorter. I've heard of cave fills on these tanks and was wondering what experience people had with overfilling these (slightly or massively, all data is useful) and then subsequently trying to get them hydro'd with a + stamp (or at all) again.

 

[Scared Silly]

The plus rating can be renewed with each requalification (aka hydro). It doesn't matter if the previous requalification stamp does not have the plus. What matters is the current test.

 

[inquis]

if I were to use a transfil whip to top up the (mostly empty after first dive) LP50 tanks from my (full) HP100 doubles, it looks like I could probably close the manifold on the lp50s and juice the first tank up into the 2800s if I have 850+psi left

Close the HP100 manifold and cascade from each in sequence. Should take an 850 psi LP50 to nearly 3100 psi and the second to ~2600.

If the REE value is stamped on the 50s, you should be able to get a +, even if it was missed in the past.

 

[drummerc]

Awesome, thank you very much guys

 

[drummerc]

Close the HP100 manifold and cascade from each in sequence. Should take an 850 psi LP50 to nearly 3100 psi and the second to ~2600.

If the REE value is stamped on the 50s, you should be able to get a +, even if it was missed in the past.

Sequence being completely equalize HP #1 with both LPs (independently) and then redo with the next HP and both LPs? (opening both manifolds at the end)

Edit: Did the math, and yes, this is ideal. I get 3038 and 2550 for final pressure of 2793 in the LPs and 2175 in the HPs (which might mean I don't get charged for 2 tanks to refil the HPs...)

 

[boulderjohn]

Before you get your tanks hydroed, check with the people doing the test.

I started a thread on this about 1.5 years ago. Here is a quick summary. I had my tanks hydroed at Force E Scuba in Florida, and the company said they did it in-house. It took a couple of weeks to get it back, and when they came back, there was no + mark. I asked about it, and they said they would take them back to get the + mark. A couple weeks later, the tanks were back, and they said they couldn't put on the + mark because their tester was not certified to give a + mark. Other people in the thread said that was pure BS--no such thing as an extra certification needed for a +.

At any rate, my tanks do not have + marks now because... because... I have no idea. It might be because the guy who inspected them didn't own a + stamp. So far it hasn't been a problem. People generally look to see if it has a current visual inspection sticker and then assume it has the full + value.

 

[drummerc]

Before you get your tanks hydroed, check with the people doing the test.

I started a thread on this about 1.5 years ago. Here is a quick summary. I had my tanks hydroed at Force E Scuba in Florida, and the company said they did it in-house. It took a couple of weeks to get it back, and when they came back, there was no + mark. I asked about it, and they said they would take them back to get the + mark. A couple weeks later, the tanks were back, and they said they couldn't put on the + mark because their tester was not certified to give a + mark. Other people in the thread said that was pure BS--no such thing as an extra certification needed for a +.

At any rate, my tanks do not have + marks now because... because... I have no idea. It might be because the guy who inspected them didn't own a + stamp. So far it hasn't been a problem. People generally look to see if it has a current visual inspection sticker and then assume it has the full + value.

Good idea. I'll double check with San Diego Divers as I believe they do hydro in-house from what their website says. They also sell the tanks, but their pricing is literally worse than anywhere else for gear/tanks, so probably would just use them for hydros.

 

[grantmac]

In Canada once anyone doesn't + rate it they never will again. I had a local shop forget the + on a tank which was having its very first hydro, needless to say I was very unimpressed.

 

[Tracy]

In Canada once anyone doesn't + rate it they never will again. I had a local shop forget the + on a tank which was having its very first hydro, needless to say I was very unimpressed.

That isn't true, that is just the line you were fed.
I hear the same thing from dive shops here in the states. They just regurgitate what they were told.

 

[grantmac]

That isn't true, that is just the line you were fed.
I hear the same thing from dive shops here in the states. They just regurgitate what they were told.

It's been consistent across 3 separate hydro facilities in Canada. Doesn't bug me much after getting a compressor.