DIR lesson 1

[Dominic]

Originally Posted by [b

Quote[/b] ]What you could do to start with is, dive with the manifold shut and practise openning then shutting it thoughout the dive.

But an open manifold is under no stress, whereas one that's closed is - opening and closing it continually will stress the manifold and make it more likely to fail.. in the same way as cylinder O-rings always seem to go when you switch on the gas, not when it's already on..

[Jay]

Originally Posted by [b

Quote[/b] (Mark Davies @ Sep. 02 2003,00:14)]Is it not possible to have a leak from a first stage O-ring that had no marked effect on the delivery of air to your regulator, but lost you gas all the same? Unless you heard it, you'd only notice it by your increased gas consumption. By that time you'd have lost a good bit of your supply.

Yes it is but if its only a minor leak then it'll be bubbling slightly. You won't notice it no matter which way your cylinders are until it goes bang. Besides, your buddy (hopefully) will have picked this up very soon in either case. Also, if the effects are noticeable then your guage will show the problem as you are checking it constantly.

[daz]

Inverted cylinders?

I would argue that inverted cylinders are less of a entanglement hazard.   Overall all I think the benefits of quicker shutdowns and less risk of entanglement outweigh the cons.

Anyway thats just my humble opinion.

Daz

[Mdemon]

Just attended a great talk on rebreathers and got to play with an Inspo.  Interestingly, AP Valves had the choice of putting the valves wherever they felt like - and they chose inverted.  

I think it probably is more streamlined Daz, but for me it's got to be the ease of reaching the valves which is the decider.  (Is streamlining  really that important for rec dives?)

[daz]

Originally Posted by [b

Quote[/b] (Mdemon @ Sep. 02 2003,22:20)]I think it probably is more streamlined Daz, but for me it's got to be the ease of reaching the valves which is the decider.  (Is streamlining  really that important for rec dives?)

Well must admit to not having been caught up in monofiliment which has to be considered a risk for rec divers but only yesterday I was doing a minor swim through of a sunk boat and despite a little knocking of cylinders to get through a small hatch it was ok.

Not sure I would have wanted my first stages banging against the hatch opening while trying to squeeze through.

Daz

[Mark Davies]

<font color='#000080'>Wasn't sure whether to put this here or on the &quot;Y-valve&quot; thread on Equipment, but this is more current.

For those that haven't followed the other thread, for various reasons I've recently put together a rig of a single cylinder (15) with a valve giving two take-offs, so that it works much like a manifolded twin-set.

I had originally intended to use it inverted (which is the reason why I've brought it up here) because initial indications were that I would struggle to reach my valves if upright.

When we got the rig together today we found that all was fine except that the hose for my secondary DV, which I had not replaced, was a little too short. As we're off to Mull tomorrow we had to find a set-up that would work so tried putting the tank upright and restoring the shorter hoses for BCD and primary DV as I had been using before with a normal valve.

On the basis of postings above I was hoping that once I got this into the water I would be able to reach the valves after all. The right valve was okay; left valve - no chance! And this was with the tank so high that I occaisionally banged my head on it.

We did notice that with the BCD that I am using the tank was a long way back, so that the top of the tank was a fair distance from my shoulder blades. I'm going to be buying a wing soon. Should a wing and harness (probably a Transpac II and Recwing) hold the tank closer to my back, or will it be much the same?