How is this possible?

[boulderjohn]

A friend of mine was diving with a group using steel tanks in Cozumel. They were at the beginning of a dive, and one of the group signaled OOA. At the surface, they took the valve off and found what my friend described as about a liter of water in the tank, and he is not the type to exaggerate. Not only that, the dip tube was GONE. As soon as the diver had gone head down, he was breathing water.

Now, you know that is not a gradual buildup over time. With no dip tube, even a fraction of that much water would have caused a problem for a previous diver at some point, unless everyone for a long period of time did nothing but head up diving. It was a complete mystery to everyone, and I cannot even venture a guess as to how it could have happened.

In case you are wanting a warning on the operator, that operator quit using the local fill station soon after that and now fills its own tanks.

 

[divezonescuba]

The top of the tank had some visual corrosion when it was brought in. Paint was bubbling off of the top where the valve sits. I would hazard to quess that the o ring was not able to seal properly because of the bubbling. The valve was very difficult to remove. If it was leaking air from the neck o ring could that somehow allow water in if the tank pressure / depth combination was just right?

I am questioning whether the tank actually always had at least 500 psi and whether it was only taken down to recreational depths.

 

[Stoo]

Air fills on dive boats are a common source of water in tanks. If the tank is kept under pressure >500 PSI at all times the source of the moisture is most likely the fill station. Filling in high humidity and/or not changing out the desiccant and filters on routine schedule would be my guess.

That's my thinking, assuming the tank has truly never been sucked dry...

Or the Masons. They're bad for this sort of thing.

 

[duckbill]

If it was leaking air from the neck o ring could that somehow allow water in if the tank pressure / depth combination was just right?

I am questioning whether the tank actually always had at least 500 psi and whether it was only taken down to recreational depths.

The cylinder would have to be down to at least 45 psig at 100 feet for water to enter. You'd have to be down near 225 feet for water to enter at 100 psig tank pressure. Not likely, eh?

And, in ANY case, for water to be able to enter your cylinder at depth the ambient pressure would have to above your supply pressure, and you wouldn't be able to breathe!

No, this was not the cause.

 

[redacted]

To get water in a tank during a dive, you would have to suck it "dry" and then descend. Not impossible but very unlikely. It almost surely entered during the filling process.

 

[divezonescuba]

Could an oilless compressor that does not use desicant material in the filter be responsible for that much water after some number of fills?

 

[halocline]

Could an oilless compressor that does not use desicant material in the filter be responsible for that much water after some number of fills?

I'm not sure, but I would think a non-drying compressor (like a shop compressor) would also produce air that's toxic enough to cause CO problems at any sort of depth. Plus I don't know of any compressors capable of pumping the kind of pressures in scuba tanks that are not breathing air compressors.

2 cups of seawater in a tank means that the tank was empty and submerged with the valve open, end of story. A significant amount of fresh water could get in from wet fills, I don't really know what constitutes 'significant' and there could be some small amount of salt dissolved in it from sloppy valve/fill whip/regulator handling, but 2 full cups of actual seawater-I doubt it.

 

[duckbill]

Could an oilless compressor that does not use desicant material in the filter be responsible for that much water after some number of fills?

If the system depends entirely on a dessicant (which it shouldn't), then maybe.
If the system has an adequate coalescer that is properly drained, then no.
If the system has a coalescer that is inadequate or improperly drained, then, again, maybe.
Even a wet whip won't entrain enough water to account for this.

 

[yardpro]

yoke or din?

din can trap water in the threads...

 

[redacted]

yoke or din?

din can trap water in the threads...

But, how would that water then move into the tank?