H-Valves & config for single tank or doubles

[lowviz]

(This is split from another thread to avoid a hijack.)

I use an H-valve on my single tanks just so that I can swap between doubles and a single without changing the hose configuration on my regulators. Post your compatible H-valve / doubles configs here for your brand of regulator. I'm starting off with Scuba Pro MK17s and MK25s. BTW, if you have found a better config for MK25 or 17 regs please share! Interesting to note that even though MK25's have a swivel base they don't dress as neatly as MK17's :shocked2:

 

[Blackwood]

Just a couple questions:

How much do you have to fuss with the hoses with the wing and backplate attached? Doesn't seem like there's much room back there (and in my experience it was a CF).



And does your wing inflator really go to the right?

 

[PfcAJ]

I would ditch the SPG on your right post (left, in the photo). You don't really need it.

 

[lowviz]

Just a couple questions:

How much do you have to fuss with the hoses with the wing and backplate attached? Doesn't seem like there's much room back there (and in my experience it was a CF).



And does your wing inflator really go to the right?

I would ditch the SPG on your right post (left, in the photo). You don't really need it.

Blackwood:
No fuss for the 17's, yes the 25's require a bit of work each time.

No, the wing inflator does an 'S' bend over the wing for the 25's, again the 17's are easy.

PfcAJ:
(I'm not DIR) if anything goes wrong in a wreck I immediately isolate and begin breathing the offending tank on my exit, never change, stupidly simple even when narced. -always have a working SPG.

 

[PfcAJ]

Good, thats the whole point. Having two spg's effectively doubles your chance of having an spg failure, thus making you go home. If you like calling dives, then leave it on there.

 

[Michael Kazma]

There is a much more important reason to only have one SPG! When diving doubles, if you have a HP failure etc. then you simply close the isolation valve, then look at your SPG and see it it holds or is dropping. The answer will tell you on which regulator the failure is and you will know which tank valve to close. If you are using 2 SPGs then you cannot figure this out in a "safe" time. If you are diving doubles then you must have done isolation drills in your class(s) and know this.

 

[lowviz]

[DIR warning: continuing to read this post will violate "don't talk to strokes"]

First, I greatly respect and admire every DIR practitioner that I can claim to know. I borrow heavily from them and my central principle is rock bottom gas management. I dive a simplified near-DIR rig that is complicated by a second SPG.

Imagine facing forward in a wreck and having a problem. I need to attend to the immediate problem, get turned around, check I'm still clear of my penetration line, identify the hazards in my exit path, and begin my exit before my only chance of a clean escape becomes completely obscured in a silt cloud from the rapid loss of gas.

My SPG's run under my arms and are clipped off to R&L D rings so I can see both SPG's just by looking down.

So it goes like this: Problem, thumb dive to buddy, turn isolation knob while watching both gauges, immediately switch breathing reg to whichever SPG is seen to drop, make mental note that you are heading OOA, identify exit hazards, BOTH GET THE HELL OUT.

Michael Kazma, you have a rebreather in your avatar and you are taking an electrical engineer to task for doubling the failure rate of a basic SPG. Secondly, how does the additional hazard of a second SPG compare to the hazards of a wreck's interior? If you are as careful as it seems, I would suggest DIR training. (As I understand it, DIR still considers rebreathers as tools of necessity, not choice, due to excessive risk)

And finally, I don't have any 'tank valves', I have a valve for each post and one isolation valve.

 

[lowviz]

Rather than edit my last post and lose context, consider this the edit:

I owe Michael Kazma an apology. I see that you weren't taking issue with failure rate, you were talking response speed. Very important in this case, completely different issue. I'm not willing to use a procedure that requires first having to close off a post, assess the result, and then possibly close the isolation valve. I'd rather just isolate, breathe whatever gas the failing side has to offer and have a working SPG for my ascent. I dive rock bottom rules so I know I'm OK with this plan. This overall procedure is not DIR procedure and thus the "DIR warning".

PfcAJ is calling me on doubling the failure rate. Based on personal experience, not an issue.

And finally, using the word 'stroke' (on myself) was considered by a DIR friend of mine as being needlessly devisive. -not my intent to widen any divisions, I'm actually very happy to be generally accepted in a predominantly DIR environment.

Lost my focus and combined the points from the last two posters, -poor form.

 

[Michael Kazma]

Did not even realize that it would still work with 2 SPGs. Better put down the beer

But I still think only on SPG is better

I also just want to point out that with one SPG you still isolate first and then look at the SPG to figure out which side to close.

 

[DaleC]

I dive with two SPG's also and would rather accept the slight risk of a SPG failure (which would happen in a non emergency situation) than diving a tank blind (as to its volume) in an emergency situation.
I have heard it said that knowing the contents in a tank doesn't really matter as you are going up anyways and you "have what you have" but I would rather base my ascent profile by knowing the volume I have.
I would like to know if I could do any deco I might have, have to alter the stops I am making or if I have to blow all my stops in order to make the surface.

I also respect the fact that others assess their risks differently.