I am a recreational diver. My dives are typically between 70ft and 100ft in 75 degree seawater. I dive single, nitrox, +/-100 cu ft, steel tanks. I always dive with a backup regulator and a partner. Years ago my dives were made with a 30 cu ft pony strapped to my single tank. I have recently quit using the ponies and I have begun to rethink the desire for using the pony. I have been thinking a lot lately about air-delivery, failure modes, between the tank and my lungs. I have read that if one were to have a free flow, that one can fold the hose over and crimp it off. Somewhat like one does a garden hose.
I have heard that primary regulator failures (the one on top of the tank), under the conditions of which I dive, are practically unheard of.
Here are the questions: I have heard o-rings pop (fail) topside, but do o-rings ever fail during a dive? Do primary regulators ever just stop working? Do hoses suddenly rupture?
I am trying to build an argument for not carrying pony bottles around in my travels.
Lee, I could not bring myself to ever talk someone into not carrying a redundant gas delivery system (pony bottle). As a good diver I am sure you plan your dives and stick to those pre-set plans, I also wager you maintain your gear and diving skills. Regardless of how hard we try and avoid becoming complacent in our diving those dive gremlins do at times raise their heads and try to ruin our day. The effort of maintaining and carrying (slinging) a small pony bottle- say 19cf is of very little effort but can play into the happy results of so many various u/w incidents. I vote you again add the insurance coverage of a pony bottle to your gear configuration.