Configuration Question

[Sharky1948]

I sometimes use a 30cf pony when diving solo, depending on the conditions and the dive profile. Typically these dives would be dry suit dives. I'm considering connecting my dry suit inflator to the pony. The logic is this: It uses a relatively small amount of air. It gives me redundancy on buoyancy, given that my BCD would inflated off of the main tank. Yes, I know I have an oral inflator on the BCD, but, in a catastrophic failure situation, who needs one more change in process to deal with? To me this minimizes the risk of task overload.

Thoughts?

Mike

 

[dannobee]

Do you have a contingency plan in place if the IP on your pony reg creeps up and the drysuit inflator cracks before the second stage does? Is there an OPV on that reg setup?

What kind of solo dives are you doing where you'd need two complete and totally separate bouyancy devices?

I dunno, it seems like it's more hassle than it's worth. Plus it requires the valve on the pony to always be on, which is something that I don't like to do.

 

[Sharky1948]

Do you have a contingency plan in place if the IP on your pony reg creeps up and the drysuit inflator cracks before the second stage does? Is there an OPV on that reg setup?

What kind of solo dives are you doing where you'd need two complete and totally separate bouyancy devices?

I dunno, it seems like it's more hassle than it's worth. Plus it requires the valve on the pony to always be on, which is something that I don't like to do.

Responding to the first question....that risk is no greater on the pony than on the main tank, so I don't see any additional risk from the rig.

Second question...any dive. While not the rig I was referring to, if you're diving double 120 steel, you need a buoyancy device to ascend...wings and/or drysuit.

Third point...you dive with the pony off???? OK...you have a catastrophic OOA situation. Now you not only have to switch second stages. You have to gain access to the pony and turn it on. That's not a situation I ever want to be in.

 

[dannobee]

The risk is there if you use a pony for drysuit inflation gas, just as it is if you use an argon setup without an OPV. The reason it doesn't happen with your primary first stage is because you're breathing from it and the IP can't normally creep fast enough. Or an IP creep could cause the LP hose to blow.

And yes, my pony is turned off, but charged (turn the valve on before going in, check the spg, turn the valve off). If you leave it on you run the risk of a freeflow causing the loss of all of your pony gas.

Gain access to your pony?? Mine is slung like a stage bottle on my left d-rings, not on my back. If I can't manage to crack the valve, purge the reg, and start breathing from the pony in less than about three seconds I probably shouldn't be diving. I think we've discussed this in the solo thread quite a number of times before and most of us dive with the valve off after charging the reg and the pony set up like a stage bottle.
I also scooter solo and there'd be no way you'd get me to keep the pony valve ON. I've seen way too many regs freeflow completely unnoticed with scooters to consider it even remotely safe.

You asked for thoughts. I'm telling you mine. Dive how you want.

 

[Fun Diver]

If the scenario you are concerned with is loss of gas in the primary tank, then you are going to the pony as bail-out and aborting the dive. Adding more air to the BC/suit appears unnecessary in that scenario assuming you are ascending. However.. an option could be to have an extra whip on the pony reg that is strapped to the pony & out of the way. If you are in a scenario where you need it then you can detach your normal whip & attach the one from the pony. I can't see any harm in it - just can't see a scenario that it will be useful. Perhaps consider simulating abort scenarios in whatever type of diving you do to feel comfortable in your gear config & relying exclusively on using the pony to get you out safely.

 

[wedivebc]

The risk is there if you use a pony for drysuit inflation gas, just as it is if you use an argon setup without an OPV. The reason it doesn't happen with your primary first stage is because you're breathing from it and the IP can't normally creep fast enough. Or an IP creep could cause the LP hose to blow.
.

This is not correct. If you have a downstream second stage attached to a 1st stage in the event of 1st stage creep (increase in IP) the 2nd will start to free flow long before the drysuit inflator lifts or the hose bursts.
I use a 30cuft as bailout all the time and my drysuit inflator comes off it. It has worked for me for years like this without any problems.

 

[bwh6]

This is not correct. If you have a downstream second stage attached to a 1st stage in the event of 1st stage creep (increase in IP) the 2nd will start to free flow long before the drysuit inflator lifts or the hose bursts.
I use a 30cuft as bailout all the time and my drysuit inflator comes off it. It has worked for me for years like this without any problems.

Hi, this is not *always* correct either. Here is an account from a diver last year whose 1st stage creeped and blew into his wing after switching to a deco gas @ 70', just about the worst possible timing.

http://groups.yahoo.com/group/ba_diving/message/23351

 

[dannobee]

Hi, this is not *always* correct either. Here is an account from a diver last year whose 1st stage creeped and blew into his wing after switching to a deco gas @ 70', just about the worst possible timing.

http://groups.yahoo.com/group/ba_diving/message/23351

That was EXACTLY the event that I remembered and why I brought it up.

Also, one of the techs here confirmed that some of the Apeks second stages won't freeflow until the IP creeps over something like 350 psi.

 

[wedivebc]

That was EXACTLY the event that I remembered and why I brought it up.

Also, one of the techs here confirmed that some of the Apeks second stages won't freeflow until the IP creeps over something like 350 psi.

Well what do you know. I still think if that did happen disconnecting the PL hose is taught as an immediate resopnse to such an event. Takes 2 seconds.
First time I have heard of this happening.

 

[SDAnderson]

I sometimes use a 30cf pony when diving solo, depending on the conditions and the dive profile. Typically these dives would be dry suit dives. I'm considering connecting my dry suit inflator to the pony. The logic is this: It uses a relatively small amount of air. It gives me redundancy on buoyancy, given that my BCD would inflated off of the main tank. Yes, I know I have an oral inflator on the BCD, but, in a catastrophic failure situation, who needs one more change in process to deal with? To me this minimizes the risk of task overload.

Thoughts?

Mike

Why not use a small set of doubles, instead?