Question Bailout gas configs for tech/deep chestmount rebreathers

[PfcAJ]

LOL no its not. All those tanks on both sides, with suit gas, suit heat, and canister lights is a giant CF. And it is in BM too, just a slightly different kind of CF. Yes if the loop hose magically ruptures you might figure it slightly sooner in a CM but accessing the O2 valve in your belly buried under all the stuff? It's not somehow magically easier and likely more difficult.

And your profile is thicker with BM bailout and CM rebreather. Silly.

 

[mr_v]

Say that to the 1000s of people with a failed HP seat in their post 2019-ish DS4

Those issues, while serious, were an outlier given all regulators in use at the time. When you're on a board and hang our with people who do serious dives and hear these issues, you'd think the universe is coming to an end. But a base rate is a base rate.

Also, knowing that we know about DS4 issues. How many tech divers who do 100m dives will NOT bench test their regs?

Finally, if we want to chat about the leading causes of tech diver fatalities, what would they be? I doubt that it is reg failure.

 

[LFMarm]

LOL no its not. All those tanks on both sides, with suit gas, suit heat, and canister lights is a giant CF. And it is in BM too, just a slightly different kind of CF. Yes if the loop hose magically ruptures you might figure it slightly sooner in a CM but accessing the O2 valve in your belly buried under all the stuff? It's not somehow magically easier and likely more difficult.

You clearly have never tried valve drills on O2 in a CM unit.

 

[justinthedeeps]

Say that to the 1000s of people with a failed HP seat in their post 2019-ish DS4

knowing that we know about DS4 issues. How many tech divers who do 100m dives will NOT bench test their regs?

Is there another thread or link on this? Does it affect any particular serial number ranges? What is the bench test?

 

[Learner Diver]

You deleted the reasons when you wrote this post my dude.

I read what you had to say about100%. What interested me was your opinion on 80% as a decompression gas. There wasn't any...

 

[Underwater Tourist]

Is there another thread or link on this? Does it affect any particular serial number ranges? What is the bench test?

search around for "apeks hp seat failure" I think there were 2-3 threads on it

It seems that factory regs that were produced upto 2021-06 are affected (you can check the date when your reg was made by looking at the serial number on the body of the first stage, it will be YYMM XXXXX - where YY is year and MM is month when you reg was made). Regs made after that date suppose to have the problem fixed

And also some service kits were affected, they are colour coded, and you would have to dig up the threads to find out which service kits are good unless someone else remembers it and can post it

edit: found those two threads, not sure if they talk about service kits, you would have to read thru them

Apeks HP Seat failure: rumor or fact?

This thread was split off from the needle valve discussion in NEEDLE VALVES Just a side note. My wife and I have done quite a few dives on unblocked 1st stages with the fathom needle valve. Sadly the reason is we've been plagued with the dreaded HP seat issues on Apeks regs that Apeks seem to...

scubaboard.com

Apeks DS4 alternatives for rebreathers

Howdy folks, The stories about DS4 HP seat failures make me think about possible alternatives to DS4 regs in rebreather setups. If you swapped out DS4 for something else, what did you choose and why? Thank you!

scubaboard.com

 

[lermontov]

I read what you had to say about100%. What interested me was your opinion on 80% as a decompression gas. There wasn't any..t

someone mentioned it- 80% isnt as effective if needed to
a) offgas
b) feed your ccr if needed
c) provide a good gas if you haver a DCS problem

versus
making your gas cover a slightly wider range while carrying the disadvantages of abc

 

[justinthedeeps]

With the 80%, yes it might be less effective at nitrogen decompression versus 100%, however if your "leading tissues" and gradients are driven by helium, this doesn't matter. But when is that the case?

And the advantage is that you can switch to it sooner, starting better off-gassing sooner, and reducing how much of the prior gas you needed to get there. Could matter when your 9 metre/30 ft stop is long, unless you're the badass up in here who just switches to oxygen there already (but no course teaches that.....right?)

Once again for both reasons we need to open a planner.

Cio before did exactly that, and (if I am not mistaken?) reported significant reductions in deco time by considering deco gases like 32/XX and 80/00.

 

[kensuf]

Couldn't agree more. But this did make me think - for units like the Fathom Mk3, it seems the common practice is to use the onboard diluent cylinder for wing/suit inflation while using offboard gas to drive the unit (whether that's in the form of manifolded doubles or SM). Since the unit would be run in a dil-out configuration, I'm assuming you get around the issue by being able to use both bailout cylinders to drive the unit in the chance you lose one? Or would you sling an extra AL80 of the same gas as your bailout to drive the unit while keeping the primary bailout cylinders untouched?

Shocking how many people are comfortable with the idea / risk profile of just swimming up to the next gas in the case of a loss of bottom gas with no redundancy. But I guess there's a reason why the Darwin Awards exist.

With the Fathom, in the cave config there's a left and right SM bottle that both have the same gas. Left bottle typically drives the unit (DILout), right bottle is the redundant bailout.

In the "Tech" config, which is two smaller volume cylinders with a LOLA manifold and pretty analogous to the Chop with doubles, one post drives the unit (DILout), the other post is your redundant bailout.

 

[rddvet]

Say that to the 1000s of people with a failed HP seat in their post 2019-ish DS4

According to the internet that is a myth. My 7 of them were caused by me. Nothin to do with apeks and their service kits. I think Ken had more than my wife and I.
But I was the a-hole for saying why I despise apeks
I’ll take all the 30 year old mk25s that haven’t been serviced in 25 years over a new shiny apeks 1st all day.