Redundancy on twin sets.

[JohnnyC]

Full open. Always.

 

[stuartv]

Actually Tbone's comment about diving with the manifold fully open go t me thinking.

Do all you boys in the New World dive with the manifold fully open?

I do and, as far as I know, everyone trained by my tech instructor does.

 

[Caveeagle]

The potential catastrophic failure is a failure of the manifold, which could potentially dump both cylinders. Although, if you shut the manifold you MAY potentially restrict to the one cylinder.
This why people get very pissed off if you lift their twinset via the manifold, you are adding a force to the manifold that it is not designed for. Potentially increasing the risk of damage to or failure of the manifold.

WTF? I've never heard anyone complain about lifting a set of doubles from the manifold. ...and I personally own three sets of double steel tanks, and am around a lot of other BM doubles divers. Seems like saying a manifold was not designed for lifting is like saying a single tank valve was not designed for the same purpose.

Actually Tbone's comment about diving with the manifold fully open go t me thinking.

Do all you boys in the New World dive with the manifold fully open?

Yes, fully open. And none of that "quarter turn back" stuff either.

 

[Gareth J]

I know of multiple people who died of hypoxia on rebreathers. I don't know of anyone who died due to suffering both the bizarre series of coincidences you postulate and then also refused to bail out when the loop became obviously nonviable.

Kevin

Hypoxia has certainly been an issue in a number of rebreather deaths.

However, if you talk to anyone diving rebreathers regularly, Hypercapnia is the thing that the majority of rebreathers fear the most. I only started diving CCR in 2003, so I was a late starter. A lot of the buddies I dived with on the deeper trips had been diving CCR for some time. So I had the advantage of learning from their experience/mistakes.

The one thing that was apparent by then, was that Hypercapnia was a major concern. A number of after market bailout valves had appeared on the market at the time, the Golom (I may have the spelling incorrect), seemed quite popular. It had become apparent by then, that the maxim, get off the loop for a sanity breath, was all well and good. But that was almost impossible once you realised that you had a CO2 issue. I remember saying that it wouldn't be long before the manufacturers had there own units as standard, a number already did. As had already happened with ADV's.

I have to be honest, I, despite my feeling that a bailout unit is one of the best accessories you can fit to a CCR, took a long time to fit one to my unit. I don't think it matters if you are a fan of eCCR or mCCR a bailout is a sensible accessory.

Gareth

My thanks to those who commented on the isolation valve being fully open.