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Dannobee...
Good points on the IP creep. I appreciate the input.
Hope you didn't think I was questioning your response...just getting clarification.

Safe diving!
Mike
 
dannobee:
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.
This is the first I have heard about such a thing and I service Apeks regs. The article above did not mention what reg was involved.
 
I am not an Apeks fan by any means, but I'd be shocked if an Apeks second stage did not freeflow until 300-350 psi. A well designed "balanced" second stage is still biased to the downstream side and will begin freeflowing when the IP creep reaches 170-190 psi. Anything more than that is unsafe and is cause to install an OPV on one of the LP ports.

Of course most balanced inflators are a balanced center valve design with no bias and no tendnecy to go full auto. So it was apparently a really cheap inflator that was also poorly maintained. I have seen some generic models that incorporate a spring under the button that returns the valve to the closed position and if you lose the button the spring departs with it and you find yourself with a runaway inflator as soon as the inflator button is pushed.

The most effective immediate action in that event, at least in my opinion and experience, is to disconnect the QD fitting on the quick release while holding the inflator elevated with the dump open as it in all cases reduces, and in most cases totally eliminates, gas entering the wing. It's one of those emergencies where messing with the posts is overkill and unecessarily complicated.

-----

As for tapping a pony for dry suit inflation gas, it's a bad idea in my opinion to plan to use your reserve gas for any purpose during a dive.

I do agree if you feel you have to have redundancy for dry suit inflation you can use another LP inflator hose off the pony. Although to be honest I don't see the need as if you have a failure, the dive is over, you will be headed up, and after ascending a reasonably short distance, you are going to be neutral and dumping gas anyway to stay that way. And if you are dving deep enough where the distance to swim up your drysuit to get neutral is excessive, you need to be diving doubles anyway instead of a single and a pony.
 
From Pete's article previously posted:

...I took a look at my right post reg last night - its screwed, IP gauge pegs
at 300+ psi. Looks like it was probably creeping and after switching to
my deco bottle and no longer relieving the pressure by breathing from
the reg, it blew out into my wing.

Later in the article:

...I've had a few intermittent IP creep issues with all 3 of my Apeks ATX
200's. Several other local divers have had issues with them. Its been my
own irresponsible fault for continuing to dive them. All of my TX50's
have been solid with no issues. I actually had the 200's serviced just 3
months ago and had said to myself if they crept again I'd replace them.
I should have never kept them as long as I did, they're history.

Here's the link to a later post where somebody screwed the adjustment knob on the second stage (TX50) to reduce freeflow (as I would on my necklace reg or on a pony setup), then adjusted the IP up until a freeflow occurred.

http://groups.yahoo.com/group/ba_diving/message/23493

I think those of us with Apeks ATX 200's went out and bought IP gauges after that if we didn't already have them.

Hey, don't believe it and dive however you want. I could care less. Keep believing that you can "just" disconnect the inflator in two seconds, dump your BCD/Drysuit and recover. Pete's ascent was 65 feet in ten seconds. If you can recognize, diagnose, and correct the problem in the two or three seconds before the ascent becomes a runaway, more power to ya. You'd be a better diver than I'd ever hope to be.

There were at least 50 posts on ba_diving after Pete's incident occurred. Sign up to the group and read them if you want. Look in the Feb 2005 folder.
 
I've had a runaway inflator on a wing and a frozen inlet valve on a dry suit.

With regard to the inflator problem, gas flows up underwater and will seek the path of least resistance so if the inflator is held overhead with the dump open most of the air never makes it to the wing. Plus the gas in the dry suit naturally vents out the shoulder or cuff dump as well with your arms raised so you won't have much if any net gain in bouyancy. That gives you a lot more than a couple seconds to disconnect the inflator hose (or even reach back and close the valve).

Detecting the problem is also easy as you hear the inflator several times per dive so the sound should automatically key you to what's "leaking" by both the sound and it's proximity. It's much easier than, for example, identifying a leaky post behind your head.

A little pre-planning helps as well in terms of ensuring the QD's on the LPI's for both the wing and dry suit have large enough knurled knobs to be able to pull them off in dry gloves, heavy wet suit gloves, etc. Most of the current crop of QD fittings are pretty minimal in the grip department with a smooth profile and very anemic knurling and that can cause problems in an emergency. You can get aftermarket cone shaped plastic sleeves that fit over them and provide a very nice lip to pull the collar back on the QD fitting. Trident also sells LP hoses and QD fittings with the same general trunicated cone shape made of solid brass much like the old Posiden inflator fittings. Either of those options makes it much easier to undue the fitting in an emergency with whatever gloves you are wearing.

This is particularly important on the dry suit fitting as disconnecting it is critical as many inflator valves will inflate the suit a lot faster than the exhaust valve will dump it. That leaves you pulling a wrist or neck seal loose to prevent the pillsbury dough boy imitation and that leaves you flooded and cold for the rest of the dive.

As for the dump-from-the-left-rear-wing-dump-while-closing-the-right-post thing...I don't know anyone who is a good enough diver to actually pull that off in a real world out of control inflator emergency. The fixation on solving the problem by shutting off the post sounds quite technically appropriate and appeals to fans of valve drills, but it is neither the fastest nor most direct way to resolve a runaway inflator problem.
 
Dannobee...
I think I owe you an apology. I was re-reading this thread and realized that my response to you might have come across as antagonistic, which was not my intention. I appreciate your thoughts and input and am always willing to learn or consider new ideas.

Thanks for the input! And, safe diving!

Mike
 
DA Aquamaster:
As for the dump-from-the-left-rear-wing-dump-while-closing-the-right-post thing...I don't know anyone who is a good enough diver to actually pull that off in a real world out of control inflator emergency. The fixation on solving the problem by shutting off the post sounds quite technically appropriate and appeals to fans of valve drills, but it is neither the fastest nor most direct way to resolve a runaway inflator problem.

Now, if I'm not mistaken, I have my inflator running off my left post, so doing the left dump and crankin' the ol' right post would be kind of pointless. In that situation, kill the left post, grab the right shoulder dump, and hope I don't become a trident missle.

As for the original post, I'd definitely encourage going with a set of doubles. Then run your drysuit inflator off the right post, then the BC off the left... And keep that pony charged but off, so you don't get an OOA, then magically realize that your 3000 psi fill managed to leak itself down to 1200 and you've got some ascent and stop time before you can hit the surface.
 
Mike Samsen:
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.

A lot of divers (including myself) dive with their pony off. What are you talking about when you say "catastrophic OOA"? You're tank exploding on your back? Maybe you need to do some drills if you have a problem with..
1- crap, my air supply is gone for some reason
2- damn, octos dead too
3- turn valve on pony
4- purge and breath.
5- surface.

This is also why I sling my pony. It's close at hand, it cant leak down if it's off, it's close at hand.

Breathing from your pony should be a drill you run often (as in the end of the last dive of the trip). Plan for the best, prepare for the worst.

FD
 
fire_diver:
A lot of divers (including myself) dive with their pony off.
If the second is burped while the valve is off, the resulting loss of line pressure can result in water penetrating the first stage. Aside from the mess this can create inside the first, water in the line can also result in a mouthful of water and a nearly instantaneous freeze, should you take a breath off the reg. If you use DIN valves, lack of line pressure can also take some of the compression off the valve connection and allow the first to unscrew a bit, creating a rather exciting whoosh of gas, should you turn the gas on.

Keeping the valve open will maintain ambient+ pressure in the line and help keep things dry and secure. If you're worried about gas loss, it isn't necessary to open the valve any more than a crack.

Works for me, at least.
 

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