Northwest Dive Club

The shop I use over fills my tanks if I'm not monitoring them. This was my last fill on one of my AL 80s. I've had over 3500# in both of my Fe 72s. What is the chance that my tanks will fail their next hydro if they keep getting over filled like this?

Aluminum will fatigue with repeated overfills and loose its elasticity (fail hydro). Steel tanks are good for any pressure that won't blow the burst disk. Steel alloys are tested for 5000 cycles, probably more than a couple lifetimes of use.
All the same, you might have a word with the shop. No point in abusing those Aluminum tanks like that.


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hydro test pressure for a lp72 is 2250 * 5 / 3 = 3750psi, they will fail with repeated pressurization like that.

fill al80s to 3800 regularly and yes they will fail their next hydro if not before. Unlike USDOT, australian requires annual hydros and their tanks just don't last because of it.

Another thought, have you checked the pressure against a second guage?

Gdog wrote:Another thought, have you checked the pressure against a second guage?

Yes, I only get fills like that from one shop

Curiosity, what do they read when you walk into the water?

The same. I know, first thought is it's a hot day in my car, but this is a normal read year 'round

Mine always drop when I get in the water. I wonder how high they are filling them to before cooling? First really good fill I ever saw at a dive shop! Be better in steels though. I pumped my AL80's about 3500 so they would be a little overfull when they cooled.

It drops, but not significantly enough to warrant heat being the factor of a high reading. I have to remind them with my 72s that they are indeed 72s not 80s and that they need to be filled accordingly. I don't breathe enough air to want a 'good fill'. A rated fill is just fine.

and you DID use another gauge to assure yours I not faulty?

Norris wrote:and you DID use another gauge to assure yours I not faulty?

yup. I find myself checking it with both gauges to make sure I am seeing what I think i'm seeing. Last night I even had Ken look at it to reassure myself my eyes were working properly.

Wow then that is just plain sloppy filling.