How much fill do you get?

[jonnythan]

Just for everyone's info, the rated psi of the tanks is at room temperature (or something close to it.. might be 70F). The cylinders are designed to hold the increased psi of increased temperature. You're not violating the cylinder design rating if you fill it to 3442 psi at 70F, but it sits outside in the heat and goes to say 3600 psi at 95F.

So I would say it's perfectly acceptable for a dive shop to pump my tanks right up to 3600-3700 psi with the understanding that they will cool to ~ 3450 psi at 70F.

If I'm wrong about the pressure guidelines and what's acceptable I hope someone will correct me.

 

[dlndavid]

Thanks all for the input, at least I'll be a little more aware when I get them filled next time. I do plan on leaving them, as the first fills (2 tanks) took an hour. But I could just hang out and talk scuba.

 

[dannobee]

Thanks all for the input, at least I'll be a little more aware when I get them filled next time. I do plan on leaving them, as the first fills (2 tanks) took an hour. But I could just hang out and talk scuba.

I've had really good luck with MBDC. Nearly always very fast turnaround and right at the top, with the tank in water.

 

[ShakaZulu]

I dove a HP120 the other day that read 4500psi, geeeezuz!!!!!!!!!

 

[KrisB]

I dove a HP120 the other day that read 4500psi, geeeezuz!!!!!!!!!

4500psi... isn't that beyond the yoke's ability? Or do you have DIN valves/reg?

If it was yoke, I'd personally be scared that the thing would break, resulting in blunt force trauma to the back of my head!

 

[jonnythan]

An HP120 would have a DIN valve, not a yoke.

 

[KrisB]

sorry... all I saw was "4500psi" ... oops!

 

[pgdive]

One thing I would say from a shops point of view is be prepared to wait if you want a good fill. To fill a tank from 500psi to 3500 at a rate that is safe and will not cause too much heat to be generated takes some time. I would love to have every customer get to the water with a fill very close to the working pressure of the tank. However a lot of time people want to be out the door in 10 minutes, there is no way to make this happen safely.

Obviously if you can leave them overnight that is the best option.

Paul

 

[redrover]

I’m a new diver and went thru this recently myself. I was getting as low as 2400 with 3000psi tanks. The shops here seem to be a bit cranky about topping off, it’s another fill off my card (both cards/shops). Now I drop them off and have them check when picking up so they have a chance to cool and haven’t had a problem since, but only 10 dives/tanks so far.
A friend has the steel higher pressure tanks and made a little sign saying something like; HP tank - Please fill to 3400 COOL - and says it solved the problem for him. (Ah, The Kraken beat me to it. I was writing when a buddy called and I had to drop and run – just got back, lousy vis for here and still pretty heavy surge.)
I don’t have a specific pressure gauge like they use at the shops to check the fill and check with my regulator via my computer. One thing – for me at least – If I don’t turn on the valve all the way as if I was going to dive with it, I will get a lower read.
I like Rick’s solution, happy to see it took someone else a lot more effort than I needed to get them to fill full, just three times making an issue.

 

[Doc Intrepid]

Had the same problem. Solved it this way. Sat down with the owner of the shop, and said "if I sign up for your blender courses, how 'bout you let me fill my own tanks?" I'd spent quite a bit of money with in his shop, and had taken trimix and some cave courses there, so he knew me pretty well. He agreed. I fill my own now, and - as some have noted - you pay for it with your time...it takes quite a bit of time to get it right for multiple sets of doubles, deco tanks, etc. I also help out by doing air fills for the shop rental tanks when they get behind. (Plus still pay for the nitrox/trimix, whatever.) Still, its a better solution than I had going previously. Something like this might work for you, if you have a good relationship with an LDS owner.