Help with tank sizing (math)

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Hey guys,

This is a great forum! You guys have been really helpful. I really appreciate the facts you pointed out and I only have one more question: Have you ever dived a Mexican cenote? They are a gas. I used to cave when I was in college and being able to float through a warm water cave is my idea of heaven.
 
Fats, depending on your location in Missouri, I have contact info for a guy that has AL80's and AL100's with fresh hydro's. When I last spoke to him, he wanted $120 for 80's and $150 for 100's.

Let me know if you would like his info. He is located in the KC area.

Lobo
 
First, you say the cylinder just passed hydro. Sounds like he is also willing to document it passes a visual inspection - but then he does want to sell the thing, so even if he is qualified/trained on the visual inspections, one can question whether he performed an unbiased inspection evaluation.
Having said that, unless really abused I doubt an aluminum cylinder from 1999 would fail a visual. I would expect worse case to be that it needs a tumble/cleaning. But you are not using it for breathing air, so that is less significant. And yes, aluminum can oxidize, but it generally just forms a very thin oxidized layer and stops, not like steel than can rust deep pits in the metal once it starts. So it is unlikely that he "doesn't trust" it. He just may not run his compressor over 3000psi, if the plan discussed is to get fills from him.

Valves: here are examples of the two basic valve types
Yoke: XS Scuba Deluxe K
Convertible (DIN w/screw in yoke adapter): XS Scuba PRO
That $100 valve sounds high, although that is the MSRP for a less common DIN/yoke convertible with a hard PVD finish.
The $150 + $30 price is not unreasonable, but also not a great bargain. If you have a local dive shop, you may just want to get aquote on a new cylinder set up the same, for comparison. The major variable is whether they are able to meet free shipping minimums or if they need to pass along freight costs. There is not a lot of margin in tanks, and it is difficult to set a price on a used tank that makes both parties happy.

I'll leave it to others to comment on carbon cylinders from China.
 
Fats, depending on your location in Missouri, I have contact info for a guy that has AL80's and AL100's with fresh hydro's. When I last spoke to him, he wanted $120 for 80's and $150 for 100's.

Let me know if you would like his info. He is located in the KC area.

Lobo
Asking for fats: Can he assume those prices include K-valves?
 
BTW: I have a local high school range instructor that brings me his scuba tanks for service. So he is fine running a high school airgun program off of scuba and adapters. No, I don't know more details on his other gear. But his tanks are all 3000, so he gets along without needing 3300 to do the job - although it is certainly more convenient to have the higher volume/pressure cylinder in your case.
 
Thanks Bob!
I was worried when I saw the Chinese tanks had metric threads. So DOT means only US threads? Or could there be a DOT certified metric tank?
(Air Rifle use 86 cu ft 4500psi Scuba Tank 2018 Gas Cylinder 300bar Carbon Fiber | eBay)

On the link you gave, there is a section about their other tanks and some of them are DOT certified.
I don't know if DOT requires US threads, but it is a US department.

If you get a 4500# pressure tank you need fills that high to be effective.


Bob
 
On the link you gave, there is a section about their other tanks and some of them are DOT certified.
I don't know if DOT requires US threads, but it is a US department.

If you get a 4500# pressure tank you need fills that high to be effective.


Bob
Bob's point is that it might be tougher to get the 4500psi fills.
 
That's the gadget! Oh, so two because you have a pony tank to take with you?

No, I use them to transfer the gas from on tank to the other....
 
Asking for fats: Can he assume those prices include K-valves?

Yes, they include k valve. Sorry, at work and didn't think to include that info.
 
https://www.shearwater.com/products/peregrine/

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