I believe they talk about the regs that screw directly into the bottle.
I'm confused by some of the responses I've gotten here.
I started this thread asking a question about a certain kind of pony regulator vs. using a standard 1st and 2nd, and I see there is some confusion about what I'm referring to. I tried to post a URL to a product on ebay, but the system wouldn't allow me to post the link. It can be found by going to ebay and running a search for the following title: 13-cf Pony Tank W/Regulator-Valve Combo & 2nd Stage
The seller said the reg is made by WMD and farmed out to Tilos. This reg is similar to the Razor product marketed by Zeagle. The shut off valve appears to be directly integrated with the first stage. There is a filling port on the side of the reg. So it seems that in order to remove the reg from the bottle, the whole valve must come off and innards of the bottle must be exposed, taking the psi to zero and requiring a new VIP. The + of this arrangement is that it's very streamlined, but I see some possible issues with maintaining it.
Two posters have responded questioning whether or not a pony is even necessary. I don't dive solo deliberately, but out of 30+ dives done so far in the caribbean I have found myself paired with "instabuddies" whose careless behavior may as well have made me a solo diver. Most of the second dives done with commercial shops on 2 tank dives are not divemaster lead, relying on buddy pairs to self navigate the area (in 50-60 ft or less). On 4 out of 10 recent dives, my "buddy" wandered off on his/her own. After surfacing and not finding them, I was faced with choice of aborting my dive, or continuing alone, since other buddy groups were elsewhere underwater and I couldn't immediately locate them.
I was never in danger of running OOA on those dives, but doesn't the phrase "redundant air source" imply back up security for a failure that is "unlikely to occur?" Yes, I have a good reg (Atomic Z1), but sudden free flow from a 2nd is not the main concern. That's what the octo is for. From my experience, the pressure gauge has proven to be the weakest link, not the 1st or 2nd stage.
On my 10th dive after cert, with a rented regulator in Jamaica last fall, I found myself having to do a CESA with no buddy in sight. I started sucking molasses at 50ft, and my gauge said I had 1500 psi left, but it was really 300. It means the gauge was wrong from the get go how much gas was in there, but I never knew.
I don't feel great about the thought of doing another CESA from 50-60ft if something suddenly goes wrong with my pressure gauge and my "buddy" is nowhere to be found. The CESA I did was from deep enough and fast enough that I put myself at risk for a ruptured lung or gas embolism if I didn't go exactly by the book. All this being said, I obviously would never use rental gear again, but do I really want to completely trust my life to a single regulator set, even if it is "well maintained?" I thought it was a given in this thread that the decision was already made to use a pony, But I'm still catching advice from people suggesting it's not necessary, and I don't get that.
