Choosing a steel tank to purchase

[Divin'Papaw]

I fill mine at home to 3800. Problem is many ow shops refuse to fill any tank beyond 3000 and often less.

I live in South FL. My HP100s are consistently filled to 3600-3900 psi. Since moving here, I've NEVER had them returned to me with anything less than 3500 psi. When I lived in Indiana I regularly had them returned to me with 3200-3300 psi, sometimes less. If I got a solid 3442 fill it was an exception.

 

[rob.mwpropane]

I fill mine at home to 3800.

The LP's or HP's?

 

[rob.mwpropane]

I regularly had them returned to me with 3200-3300 psi, sometimes less. If I got a solid 3442 fill it was an exception.

This is the norm in MD. Between the drive, the wait, the sales pitch everytime I walked in the door I did the irresponsible thing and bought a compressor.

 

[boulderjohn]

It also may depend upon the individual filling your tanks.

I used to use a dive shop in Florida whose manager and most staff refused to fill my LP tanks TO their rated capacity, let alone above it. They said it was too dangerous. Upon getting a fill to 2500 rather than the rated 2640, I was told I was "splitting hairs." In contrast, they filled all their rental AL 80s to 3300.

However, one of their employees, knowing I used those LP tanks in caves, routinely filled them well above 3000.

I switched to another shop, and they regularly filled those LP tanks to the 3200 range.

 

[marginwalker]

Thanks to everybody for all the great information about tank choices and dive shop fill expectations! It sounds like the HP100 is a good choice according to most, so that is what I am going to be looking at.

 

[rx7diver]

I bought a set of HP100 doubles that are 3500, but it's fine as they came with the manifold. They are painted, I take them in salt, I'm just a lot more careful about giving them a good rinse. I have asspirations of one day stripping them down and using cold galvanic paint.

@rob.mwpropane ,

Your PST HP100's (3,500 psig) are galvanized beneath the paint, so no need for you to worry. Leave the paint in place, but continue to wash them thoroughly (with boot removed) after a salt water dive--like you're doing.

Attached pic is of my HP80's fresh from a new hydro a couple of months ago. These are my first cylinders ever, purchased new in 1988. Perfect with my Scubapro Stab jacket (and my FD RX-7!). Too short (for me) for my SS Freedom Plate. I really, really wish I still owned the two (unpainted) HP100's that I replaced with HP120's (unpainted, too, and currently being hydro'd).

rx7diver

 

[rob.mwpropane]

@rob.mwpropane ,

Your PST HP100's (3,500 psig) are galvanized beneath the paint, so no need for you to worry. Leave the paint in place, but continue to wash them thoroughly (with boot removed) after a salt water dive--like you're doing.

View attachment 683321

Is that an unknown-to-me fact? I have 2 sets of painted 100's, the chips that I see do not show galvanized underneath, but I could be wrong (this is always a possibility)

 

[rx7diver]

Is that an unknown-to-me fact? I have 2 sets of painted 100's, the chips that I see do not show galvanized underneath, but I could be wrong (this is always a possibility)

Well, I have always understood that the "Sherwood Genesis HP" cylinders are hot-dip galvanized (like many other of the PST cylinders).

I just googled. Conventional internet wisdom seems to corroborate this.

P.S.: My personal HP cylinders have only ever been in fresh water, so my personal experience is no real help here.

rx7diver

 

[Eric Sedletzky]

Yes, it depends upon your location.

My LP 85s are routinely filled above their rated capacity, sometimes well above it, and I am not talking about cave country.

In contrast, since I have owned my HP 120s, I have never had them filled to their rated capacity.

Just go to a dive shop with a new fill monkey. Chances are good they’ll think it’s an aluminum 80 and fill it to 3000 psi.
That can also be a downside to hp100’s, the same fill monkey will fill that to 3000 thinking it’s an aluminum 80.
They think everything’s an aluminum 80, until you say something.

 

[Eric Sedletzky]

Every painted tank I’ve seen that had the normal little chips with some spot rust, or ones I’ve stripped and/or repainted were all bare steel under either light grey or white primer with a topcoat. Both most likely two part urethanes. I’ve never seen hot dipped galvanizing or sprayed zinc rich primer under paint.
Also, I just completely stripped a vinyl coated 1969 steel 72 that was a freebie. I striped off all the thick rubbery vinyl. A lot of areas had hidden rust under the vinyl coating. After it was completely clean and blasted I primed it with a two part epoxy primer, and now it’s ready for paint, then it will go to hydro. There was no galvanizing underneath, just bare steel.
I have another Faber painted steel 85 that was a freebie because of bad rust and pitting under the
Boot. All the rust got sand blasted and primed with epoxy two part and it passed hydro no problem. No galvanizing under the paint, it was bare steel under a white primer and charcoal grey metallic topcoat.
It wouldn’t make any sense for companies to paint over hot dipped galvanized tanks. That would add labor and added material expense, not to mention special primer to get anything to stick to zinc.

Hot dipped galvanizing is the premium finish for scuba tanks…….unless the tanks are free then paint is OK. But I would never spend money on a brand new painted tank.