Double tank SPG question

[MidOH]

I did the indy route. Spg on each side. Full redundancy. No valve drill.

So its like diving two little rigs. No extra training required.

 

[tbone1004]

That's what I intend to do as well, as soon as my transmitter arrives.

don't bother, keep the SPG in your regulator bag just in case but having redundancy in pressure is unnecessary. Like Grant and AJ said, if you have to turn a bottle off, you either have enough to get out or you don't. If you don't, you weren't going to have enough to get out to begin with and should have had better gas planning and knowing that you don't will only make matters worse.
Hell once I have turned a dive whether it's in a cave or a deeper OC dive I don't check pressure on the way out unless I'm trying to record something specifically

 

[PfcAJ]

It’s been said but is worth reiterating, your SPG is the backup.

You need to know what your gas will be before you look at the gauge. That’s “primary”.

 

[Angelo Farina]

Yes, that's what seems obvious to me. Having to shut down one of the two tanks (and with that half of the remaining gas) would be a dive-ending event. For me at least.
I was just wandering about the redundancy principle, which apparently does not extend to the SPG.

Shutting down one of the two valves does not shut down the corresponding tank, You still have all the air, but just one reg and no SPG.
The case in which you loose one tank is when you are forced to close the separation manifold. Which in my experience I have never seen happening (and in fact I have no separation manifold because it is substantially useless, it is just another failure point, and the risk of having it closed by mistake is serious).

 

[azstinger11]

SPG on left post, AI on right post. SPG and AI validate each other for pre-dive check, then in the event of isolation have the ability to get pressure from the tank I’m breathing off of. That being said, dive is over and heading up, as soon as available after isolation.

 

[kierentec]

One of the reasons/advantages of having your SPG on the left is it will tell you the status of your left post/isolator. Most people that add a transmitter to their right post aren’t checking the SPG, so won’t notice when they roll off their left post until they need it.

No need for it, adds a failure point, creates bad habits.

 

[L13]

... No need for it, adds a failure point, creates bad habits.

How does it add a failure point? While a transmitter might fail to transmit, it is no more of a failure point with regard to air loss than the plug with o-ring that it replaces.

 

[kierentec]

I had one blow apart a ways back in the cave a couple months ago. I was trying out using them for O2 monitoring on CCR.

 

[stiebs]

How does it add a failure point? While a transmitter might fail to transmit, it is no more of a failure point with regard to air loss than the plug with o-ring that it replaces.

A plug with an o-ring is just that. A transmitter and SPG require that o-ring, plus a hose (with connections on each end) plus a spool.

I've never seen a HP hose fail at the first stage connection. I've often seen HP spools fail.

 

[ChuckP]

I was taught that the amount of remaining gas really means nothing and would potentially add stress to an already stressfull situation but as I dove more and more I thought of it in a different way..

What if a second diver had a problem, how much could you assist? I do not cave dive but do dive soft overheads and some restrictions and rarely dive doubles anymore but dive single backmount with slung 80's - everything has some way of knowing gas remaining.

In any failure, my first motion would be to eliminate the proble then exit/turn whatever, not look at a gauge.