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Can't agree with you on this one Art. I agree with Kevin that the use of a pony is better than the use of a single with a Y-valve. I've seen the first stage o-ring go and it's not necessarily a slow leak. What about a low or high pressure hose blowing or emptying the tank? I've never known anyone who dived a Y-valve so maybe I'm missing something. I dove singles for a long time, sometimes incurring a very long deco. I'll admit that this was stupid but air consumption was so low that the added weight and expense of doubles was prohibitive at the time. I only went to my pony once during a very long deco using a single. This was before I was diving Nitrox and stages. I didn't need to switch to the pony but since my main had hit 500 psi I opted to switch to the pony for the remaining 10 minutes knowing that my mains were working and I could always switch to that. Had a 40-cf. pony that is now a stage bottle. Not saying that diving singles is acceptable for deco, only that having a completely redundant air source is better than only a redundant reg. I wasn't going into wrecks with singles so snags on the valves weren't a problem. I don't think anyone diving anything but doubles (or a rebreather I guess) should be going inside a wreck. Art. -----Original Message----- From: Art Greenberg [SMTP:artg@ec*.ne*] Sent: Friday, January 15, 1999 3:16 PM To: Scaleworks@ao*.co*; cobber@ci*.co*; Rubrifolia@ao*.co*; Wahoojan@ao*.co*; techdiver@aquanaut.com Subject: Re: usefull pony bottles ( was which course& school) At 01:51 PM 1/15/99 EST, Scaleworks@ao*.co* wrote: >To suggest that a single with a y valve is a better setup is absurd. Where is >the redundant air source? Why is the single w/pony better than a single w/Y valve? (Let's say the diver owns his/her cylinders so employing a Y valve is an option). The only failure point advantage of the pony would be the burst disk and neck o-ring. Neither has a high failure rate. The failure mode for the o-ring, when it does fail, is usually a slow leak that in no way would require a bail-out. We all know how to make the risk of burst disk failure zero. If you're willing to discount these advantages of the pony because of the low likelihood of failure (the sort of calculated risk we take all the time), then all you're left with is more gas. Then I think gas management and dive planning are the proper tools, not the pony bottle. Art Greenberg artg@ec*.ne* -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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