Steel tank buying decision

[spectrum]

Some speckles are not uncommon. If they are anything but the lightest blemishes it's common practice to spin a cylinder brush in there to polish it up, maybe next year.

It does not sound remotely worthy of a tumble. I'm not familiar with any chemical rust removal process for scuba cylinders but it sounds scary.

Pete

 

[cricfanSD]

Thanks.
>>You mentioned the tanks were O2 cleaned before, but I get the impression you are not going to >> maintain their O2 clean status.
No I didn't want to maintain the O2 clean status. Most of the diveshops here do not use PP blending for Nitrox which helped my decision. Any pros and cons ?

 

[pescador775]

Here is a CON. Cleaning is likely the cause of the rust. Most of these O2 preps use water and detergent inside the tank.

 

[oxyhacker]

Speckling, if by that one means little scab like rust concentrations, can mean just very light rust, or that the rust is concentrating itself rather than spreading itself all over, and this can cause deep pitting. I get more nervous if someone says "there's just some spots" than if they say "the whole inside is covered with it".

Hard to say for sure without seeing it, but if it looks like little scabs one could (if they were scabs) pick off with one's fingernail, then think I would do something right away rather than waiting until next year.

Some speckles are not uncommon. If they are anything but the lightest blemishes it's common practice to spin a cylinder brush in there to polish it up, maybe next year.

It does not sound remotely worthy of a tumble.

 

[cummings66]

I don't know for sure about it without seeing the cylinder, but on mine when I do the vis on them I remove all rust before I close them up. Cleaning a cylinder to O2 standards does not mean you will have rust, that happens if you don't finish it right. N2 flush to dry it out usually keeps rust from happening, but if it does you can use Compound O or a blend of your own design to keep it from flashing.

IMO rust shouldn't be left in a cylinder if it's more than a very light surface flash. I think if it was mine I'd get them cleaned. In fact I did clean mine.

 

[Craig Baumann]

I have gone to LP steel tanks for open circuit technical - Worthington, double 108s. They are huge, AND heavy. I went LP so I could cross-fill from my steel HPs. I decided on 108s, again, because of a cross-fill consideration - the larger the tank, the more air I could transfer from my HPs to my LPs in the field. The other possibility was LP 95s which I have used in the past and enjoy, but again for various reasons I chose the 108's for purchase... (higher profile, and easier to climb into.)

For single tank dives there's really nothing I like better than steel HPs. They are compact, easy to carry and use and negatively buoyant, filled or empty. I would love to double them up and I may do so one day, but for now, LPs in the field, especially in double applications and in places where I will not be sure of getting good high pressure fills, are the answer.

CB

 

[SparticleBrane]

^
Let's say you were deciding between double 119s and double LP95s.

They're the same physical size, just rated to different pressures.

At identical pressures, they hold the same amount of gas. Kinda throws the idea of "more gas at lower pressures" like you mentioned in the last sentence, right out the window.