Cave fills?

[CaveSloth]

Any reason why a steel cylinder from the 1970s can't be overfilled same as a new steel cylinder if it passes hydro?

 

[Superlyte27]

Any reason why a steel cylinder from the 1970s can't be overfilled same as a new steel cylinder if it passes hydro?

Steel 72's aren't the same as lp85's

 

[CaveSloth]

Steel 72's aren't the same as lp85's

Oh? So it isn't just like an "LP72"? Unsafe to overfill?

 

[BRT]

Oh? So it isn't just like an "LP72"? Unsafe to overfill?

I'm certainly not comfortable pumping old steel 72's to 3800. But some do. Nobody has yet come up with a failure of a steel scuba tank in hydro and viz.

 

[Superlyte27]

Oh? So it isn't just like an "LP72"? Unsafe to overfill?

I won't do it, if you cut one in half those tanks are thin as hell.

 

[SandyRobinson]

I'm certainly not comfortable pumping old steel 72's to 3800. But some do. Nobody has yet come up with a failure of a steel scuba tank in hydro and viz.

I limit mine to 2500 and have written that across the neck of the tank as a reminder to the fill station.

 

[Dark Wolf]

I cant help with the shops in your area. Sorry.

I regularly fill my LP95 doubles to 4k. My LP85 doubles also get overfilled to 3500 or so.

As stated upthread, when I get my LP72 sets assembled they will be overfilled, though not as high.

DW

 

[Caveeagle]

Also yes, I agree that 108's would be nice. Taking a look at the cylinder specs, they seem to be about the same size, weight, and buoyancy characteristics as my HP100's.

LP108 and HP100 are totally different tanks and sizes. The 108s are 8” diameter and significantly fatter tanks.

From an internal volume standpoint, your HP100 tanks are pretty much the same as LP85s. The 100s have a bit thicker steel and are a tad heavier. If you are diving salt water, and possibly dry-suit, you are far better off staying with the HP100 tanks.

one of the only reasons LP85 / LP108 type tanks work well for cave diving is that they rarely get breathed down more than 2/3rds of the initial fill. So even at the end of a typical cave dive, they are still a little negative.

Does cave filling a lp steel tank reduce it's lifespan?

no evidence to support this.

like CaveSloth, I have a set of LP104s that have born on dates from the early 70s that were purchased from a well known Florida cave explorer. I am quite certain these babies were hydro’d far more often than the required 5yr interval. They past their last “official” hydro in 2018.

I also have 3 pair of old LP72s that are all in use. I will fill these up to around 2600, which makes them great for single tank, or SM cavern diving. As has been stated, they are thin, and there is no way I would pump them up as high as modern LP tanks.

 

[broncobowsher]

And if you are in a place that doesn't have over fills, does it really matter?
Yes, in Florida you can get cave fills. The rest of the world that would be a shop that accidently filled an LP tank thinking it was another AL80.
I have had one boat (that is no longer in business) in California that gave me a 3800 fill, once. I think the deckhand was distracted or the gauge was broken.

 

[NAM001]

These threads always seem to come down to cave divers saying "We don't have any problems despite filling it like this over the years," while people outside of cave country saying "You shouldn't overfill tanks, it is dangerous."

Which is right? That is for each person to decide, but I have a set of LP85s in my trunk that are at 3,800psi the last time I checked them.

One opinion is based on experience and the other is based on what they have been told to believe.