Mscdex
Contributor
With all this pony talk, I was wondering how people store a 19cf pony. Since you hopefully will not use it any time soon, do you keep it full or bleed it after a dive?
How to store a pony....stable
- Thread starter Mscdex
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Always full, same with most of my tanks. But then again I go diving a couple times/month.
Dr. Lecter
Contributor
Keep them filled with a caveat: pony tanks tend to be AL, so there's the SLC issue. Probably draining it down once a year is fine, but I'd tell the shop doing the viz to pay attention to the tank neck threads because it was stored at full pressure for the last X months. Ponies by definition tend to be filled with cheap gas like air, so using them every once in a while is probably good for your skills and the tank without harming your wallet.
OP
Mscdex
Contributor
Great. Thanks for the info.
I keep mine full, but I also breath it on my safety stop for a bit on my last dive of the day just to practice using it. Then I also clean both regs under pressure and then breath the reg for a few puffs after , so I usually get pony topped off at beginning of every boat dive, and or every few trips to dive shop. (Dive shops fill ponies for free typically)
on a similar note I'm going to start breathing my pony reg even more on my last dive at safety stop, I probably had it down on about its 100th dive , in saltwater with very limited use, and it was sucking water, and when I cleaned it and turned off my gas it's diaphragm wouldn't lock up and just breathed straight through (but not air from tank), i chalk it up to being dipped in saltwater continually but not being breathed very often....this is a hog regulator which has a great reputation. I had Robert from Scubatude service it, and he was surprised I think at level of corrosion in a fairly short time. I think there is something to be said for equipment being used to keep it functional, and a pony regulator gets very little use but gets put into pretty harsh conditions!
on a similar note I'm going to start breathing my pony reg even more on my last dive at safety stop, I probably had it down on about its 100th dive , in saltwater with very limited use, and it was sucking water, and when I cleaned it and turned off my gas it's diaphragm wouldn't lock up and just breathed straight through (but not air from tank), i chalk it up to being dipped in saltwater continually but not being breathed very often....this is a hog regulator which has a great reputation. I had Robert from Scubatude service it, and he was surprised I think at level of corrosion in a fairly short time. I think there is something to be said for equipment being used to keep it functional, and a pony regulator gets very little use but gets put into pretty harsh conditions!
OP
Mscdex
Contributor
Did not realize that dive shops were so generous with the refills. Practicing with it sounds like a good idea. In a stressful moment, you want that automatic reflex.
Dr. Lecter
Contributor
Not all shops will be so generous, best to check in advance. That said, even if it's $5 or $10 to fill the pony, it's a good investment to practice your ascents on it every so often.
Mscdex,
If you have a tank equalizing whip, you can use this solution: The Luxfer Web site (L6X® aluminum cylinder specifications - Luxfer: Setting The Standard Worldwide) lists the following:
A Luxfer Al 80 contains 77.4 cu ft at 3,000 psig, and has an internal volume of 687 cu in.
A Luxfer Al 19 contains 19.9 cu ft at 3,000 psig, and has an internal volume of 175 cu in.
So, at the end of your diving season drain both your Al 80 and your Al 19 pony to 300 psig, and store them away (standing and chained/roped/bungeed).
At the beginning of your next diving season, have your Al 80 filled completely. Then use your equalizing whip to *slowly* equalize your Al 19 pony with your Al 80. If my back-of-the-envelope calculations are correct, both tanks will equalize out to ~2,400 psig! Go diving with these tanks. The first dive of the new season will be relatively shallow, correct? So 2,400 psig in your Al 80 and Al 19 should suffice.
Next time you fill your Al 80, equalize your Al 19 pony again. Now your pony and your Al 80 are both full (essentially) and are ready for your second dive of the new season.
Safe Diving,
rx7diver
P.S. Um, check my quick calculations, though! Might be better to drain only to 500 psig.
P.P.S. Of course, if you're using a HP 80 or HP 100 (instead of an Al 80), you will be able to completely fill your Al 19 pony the first time you equalize.
Kharon
Contributor
Yeah - that works with aluminum at 3000 or higher. I dive LP steel (2640) recreationally. I pay my dive shop the full shot for a pony because it's as much trouble for them to fill it as an 80. It's a small price ($6-$7) and it's only once or twice a year. It needs a vis once a year anyway and that's usually the only time it needs a full fill.
I regularly practice switching to the pony on rec dives and do what you suggest (top it off) when I'm working (milfoil remediation). There we are using al-80's and topping my 13cf from 2500 to 3000 doesn't take much gas from the 80 and we always have more tanks than we'll use for the day anyway.
The only other times I need a full fill is when traveling (empty and open). I've never been charged for a fill at my destination. I try to get my vis (and hydro's when needed) in late winter, after I get back from where ever I've wandered to.
So my tanks, pony included are full almost all the time. With a vis every year I don't believe they need to be drained over the winter. Neither does my dive shop. They suggest storing on the side and rotating them an eighth to a quarter turn each month, just in case.
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