Spare Air & Pony Tank

[eandiver]

needless to say we both use 19cf ponys now and the spare air is gone.

Of course the steel tanks and DIN valves are much better for showing off on the boat deck than a spare air.......

 

[ArcticDiver]

I've really enjoyed this thread and the discussion on Pony vs. Spare Air and the stories that help me understand each person't viewpoint.

But, I haven't seen much on just using doubles. I've met a few folks who travel a lot, as I do, and who have adopted doubles. They travel with their regulators, except they have an extra reg and the piping and strapping to make a double. I've seen this on a liveaboard and on day charter boats.

So, how about it? Pros and Cons on just solving the problem by using doubles.

 

[bluemagoo]

I have an older SpareAir (1800psi, 2.0cuft model, no required inspections) and it nearly always leaked air. The single-stage regulator valve is a very basic upstream design with a plastic cone-shaped plunger against a orifice disk with a sharp-edged metal seat. The plunger is easily scored by the seat and eventually, the plastic gets scraped or misshapen enough that the seal isn't perfect. The problem never went away, even after rebuilds. The regulator valve assembly itself frequently leaked because it couldn't be tightened very much; it took absolutely zero effort to turn it side-to-side almost a 1/4-turn -- further tightening was prevented by a cutout to provide clearance for the central hollow screw holding the burst disk. It was annoyingly common to have a small leak from the valve assembly because the o-ring couldn't be seated firmly. Moreover, if the main valve is turned closed too tightly, its nylon seat can also get scored and spring a leak; or, if opened too aggressively, the entire main assembly could be loosened and unscrewed. I took to diving it with the main valve shut (which was reported to be SOP with the helicopter crews who were issued the SA). But after some time, I decided that I dove conservatively enough that the SA was more trouble than it was worth and quit strapping it on regularly. I don't know anything about whether these problems still exist with the newer 3000psi models.

I also would be interested in how travelers manage to use doubles. The double regs are fine but what about the manifold? I don't imagine that rental rigs with dual ports and isolator valves are that commonly available, except maybe where cavers and deep wreckers are frequent customers.

 

[ArcticDiver]

...I also would be interested in how travelers manage to use doubles. The double regs are fine but what about the manifold? I don't imagine that rental rigs with dual ports and isolator valves are that commonly available, except maybe where cavers and deep wreckers are frequent customers.

I don't know how everyone does it. But what I saw in BC was typical of my experience. The traveling diver had everything with him except the tanks themselves. The dive operator furnished the AL80s. The first time he put them together as doubles it took a fair amount of time; maybe 15 minutes or so. After that he changed tanks just as fast as any of us using singles.

Assuming that is typical; why not travel with the manifolds and regs? A couple tanks from the diver operator and your in business. Everything is on your back and out of the way and you always have twice the gas supply you have planned to need. Initial impression is that doubles would be a much easier, neater and safer way to carry spare/emergency gas.

 

[Mandy3206]

I don't have a manifold or the regs for the double tanks setup, but I think that all quality gear for doubles, use DIN configuration instead of Yoke valves. Am I right?

If so, I think it may present a problem since most rental tanks are in the Yoke configuration.

Any coments on this would clarify thing for me.