hydro +

Do any shops in SoCal do + test on the tanks when they hydro them to keep the plus?
i never seen a tanks with a hydro with a plus after it except from the manufacture

pacific wilderness in san pedro

fishfood:

Do any shops in SoCal do + test on the tanks when they hydro them to keep the plus?
i never seen a tanks with a hydro with a plus after it except from the manufacture

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This is an issue that is a cross between not understood and political. Most dive shops will tell you it is illegal to perform a + hydro after the first one, quoting both federal law and service bulletins from the tank manufacturers.

Poppycock - the only thing many dive shops want is to move new merchandise, preferably stuff they have on the floor/in stock (at least where I live...).

Pulled the CFR they referred me to, and lo and behold, it contained the exact procedure for re-qualifying a tank for a + mark. Illegal my 6-O'clock! As far as manufacturers bulletins, well, there are many more hungry lawyers in the world than manufacturers so .....

All that said - I did my homework and started calling shops, and 'bout 4 weeks ago I had one of my steels hydro'd through a shop 4 hours from home and indeed it requalified and has a brand new + mark. Found some actual hydro shops closer to home since then that they can be taken directly to and eliminate the middle-man.

There are several threads that discuss this on the board, think most of them are in the tanks/bands section, but this is my personal experience with the issue.

Tom

Thanks Tom - do you still have that CFR cite handy?

If not, I'll search the other forums

Thanks

Chris

So what does the + mean?

Tamas:

So what does the + mean?

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Means the fill station can pump the tank to 10% over the pressure stamped on the tank. Interestingly, many folks don't realize that tanks volume, i.e AL80, only has 80 cu ft of air if overfilled by 10%. Tank volume is rated on the 10% over assumption.

....or so I have been told.

Terry

Good to know, I was not aware of that.

ChrisM:

Thanks Tom - do you still have that CFR cite handy?

If not, I'll search the other forums

Thanks

Chris

Click to expand...

Don't have it anymore but it's on a DOT website and google will probably bring it up. BTW - the + marking is only valid on "low pressure" steel tanks and it was/is used as a marketing ploy. For instance, a LP 95 is only 95 cu ft at the 10% overfill (2640 psi). The 2400 PSI rating stamped in the tank will get you high 80-something.

+ hydro stamping on aluminum tanks are grounds for immediately condemning the tank - they're not legal for further use. An AL 80 is usually 77-something depending on which manufacturer and which model.

High pressure steels are not victim to the marketing ploy and have the advertised volume at their rated pressure. For instance an E8-119 is 119 Cu Ft at 3442 PSI (it's rated pressure).

Tom

Everyone should have this webpage bookmarked:

http://www.huronscuba.com/equipment/scubaCylinderSpecification.html

It shows service pressure, tank capacity, buoyancy, etc.. Its also great for figuring out weight changes when changing tanks...

As you can see on the chart, and as skyking pointed out, the service pressure only applies if filled "+10%" for steel tanks rated under 3400 psi. There is no "+10%" for aluminum tanks as far as I know.

However, they allow rounding up when marketing, so as previously stated the service pressure for an Aluminum catalina S-80 is 3000psi, and holds 77.4 cubic feet of air.

I've never owned a LP steel tank, but I would be pretty peeved if I got it hydroed and then found out I lost that +10 percent!

Scott

Thanks for the correction skyking. I was on the right track, just off center a bit.