OP
MasterGoa
Contributor
Nope...
100% Free flow at 135Ft and 41F water
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Nope...
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Yep.
The answer you received indicates that the tech doesn't understand hose construction or failure modes.
You can do whatever you want, but whoever thought up that answer wouldn't be working on my stuff.
Terry
charlesml3
Contributor
What? I've read that reply now three time and can't make any sense of it. Are you suggesting that using your buddy's Octo is a bad idea because doing so would cause a freeflow there?
-Charles
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Yes. Most non-cold water regs are very close to their freezing limits (or in this case, beyond) when used by one diver in very cold water.
Adding a second diver to the same first stage (sharing air) stands an excellent chance of causing a freeflow on the donor's equipment.
Terry
Even breathing off the reg while inflating a BCD or drysuit at the same time can cause a freeflow. Of course a stressed diver sharing air is definitely even harder on it. My understanding is that as the air comes out of the tank and goes through the reg there is a significant temperature drop due to the change in pressure (the reverse of when you get your tanks filled and they are warm). So this cold air combined with cold water causes ice crystals to form. The more air going through the reg the more potential for this ice crystals to form and cause the freeflow. Keep in mind that we are talking very cold water - I noticed you are in North Carolina so the warmer water you dive is likely to act as a heat sink to keep this problem from occuring.
Ahh the joys of cold water diving ... take home msg is to have the proper equipment for the dive you are doing.
elan
Contributor
Yes that's exactly what I was trying to say. The load on the 1 st stage of the buddy's reg will be even more than 2 times as much as the out of air person in most cases will be breathing harder. 2 persons one of which will be stressed will cool down the buddy's first stage much quicker thus the probability of his reg to start free flowing rises. If one has a pony bottle with her one should switch to the pony, and forget about the buddy octo.
Charles,
I think the point you are missing here is that the primary second stage isn't the device that has failed. It is the first stage. Both second stages are attached to the failing first stage. If you switch to your octo (redundant second stage) and breathe from it, most likely you will now have two 2nd stages blasting gas from them, making the gas in your tank go away faster and causing more of an issue.
Assuming we are talking about high performance regs - two freeflowing second stages will not empty your tank any faster. The reason being is that the limiting factor for air escaping from a freeflowing first stage is the opening in the tank valve and not the second stage. That said - I do agree that if you have one free flowing second stage and make the switch thinking that you are going to make things better and it starts blasting air out of it too, your stress load is going to go through the roof and a person could easily think they are going through their air twice as fast.
ChangeAgent
Contributor
Here is what I did, as it happened to me a long time before. Switched to octopus, and took hose of first free flowing reg and nicked it so it stopped blowing. Made my way to the top.
With a second stage in free-flow you also have the risk of your first stage freezing in cold water. So to stop it running free is important for your own safety.
Glad to hear you managed though. Suggest you run the incident through your mind a few more times, but this time doing all the right things. This is a great way to train your self. I was a S&R diver for years and we did scenarios all the time in the dry. Just to get it in to your brain as a sequence that needs no thinking. I still do all kinds of things on every dive, like find knobs, SMB, etc. Just let my hands wander there so ÁÕhey know where it is.
With a second stage in free-flow you also have the risk of your first stage freezing in cold water. So to stop it running free is important for your own safety.
Glad to hear you managed though. Suggest you run the incident through your mind a few more times, but this time doing all the right things. This is a great way to train your self. I was a S&R diver for years and we did scenarios all the time in the dry. Just to get it in to your brain as a sequence that needs no thinking. I still do all kinds of things on every dive, like find knobs, SMB, etc. Just let my hands wander there so ÁÕhey know where it is.
mpgunner
Contributor
This is a great thread. I'm also looking at a pony for my deep diving in the puget sound. My group regularly dives to 120+ with temps down to 42. Having a complete alternate system would be good.
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