Regulator sets for double tanks

[sgl308]

I'm looking to slowly purchase gear for diving doubles, and was curious how the techies are setting up their regs. What I'm looking to get into is cave diving, wreck diving, and deep diving into wrecks and/or caves.

My big question is how each of the two regulators are set up. How many 2nd stages are used? Which side does the dry suit inflator hose come from (if I'm not using a separate bottle specifically for the suit)? Are their SPG's off each 1st stage?

Any advise will be appreciated, any bickering or "my reg is better than your reg" will be ignored. Thanks.

 

[DevonDiver]

Here is a regulator set-up using Apeks regs...

Here is a set-up using Scubapro Mk25s.....

On the RIGHT HAND post you have:
Yellow: Primary Long Hose
Blue: LPI Inflator

On the LEFT HAND post you have:
Red: Secondary Regulator (bungeed around neck)
Silver: Drysuit Inflator (if reqd)
Black: SPG

More details and instructions on this (very good) site: FKD - Doubles Regulator Config

 

[sgl308]

So why only one SPG on the ScubaPro setup? What happens if the left side fails and you have to isolate that side? How do you know how much pressure you have left in the right tank?

And I'll check out that link.

 

[DevonDiver]

Any advise will be appreciated, any bickering or "my reg is better than your reg" will be ignored. Thanks.

This is tech diving, not a holiday camp PADI world of 'high fives' in poodle jackets Experienced tech divers do tend to be more forthcoming with strong opinions... it's worth developing a thick skin to that... but also keeping your mind open to the value of those opinions.

 

[Wookie]

So why only one SPG on the ScubaPro setup? What happens if the left side fails and you have to isolate that side? How do you know how much pressure you have left in the right tank?

And I'll check out that link.

Doesn't really matter how much gas you have left, the dive is over and you pray to god you have enough left to get out/up. Watching a gauge creep to zero isn't going to help your well being.

 

[DevonDiver]

So why only one SPG on the ScubaPro setup? What happens if the left side fails and you have to isolate that side?

There's only one SPG on either/any of the rigs.

If you have to isolate, then there's only one direction you will be going.... UP.

If you're going up, then you won't need an SPG for the other tank. You'll be well aware of how much gas you had... and how much you need... because you'll have planned your contingencies long before getting into the water....

How do you know how much pressure you have left in the right tank?

If they are manifolded, then they function as 'one big tank', so one SPG is sufficient. If you have to shut down the isolated manifold, then you're dive is over. Your gas planning has ensured that you have sufficient in your remaining tank for your ascent to surface or 1st deco gas (whichever is relevant).

 

[sgl308]

And if my wing has a dual bladder, I'm guessing the second lpi hose would come off the left side...

Thanks for the info so far. It has cleared up a lot!!

 

[Wookie]

I wear a dual wing, and I actually don't cross hoses. Left post reg has main inflator, Right post reg has backup inflator. I just have to find wee inflator hoses. Interestingly, I use the exact same reg setup when I dive single, only I put the right post reg on my pony, which I wear on my left side, and my left post reg on my main cylinder.

 

[DevonDiver]

Yes, if you had a dual bladder wing, then you would configure a second LPI from the left side post.

Some consider it 'best practice' to not actually connect the second LPI to the inflator though... as the risk of air accidentally leaking into the redundant bladder could post a dangerous runaway buoyancy threat on ascent. Other will argue that a buoyancy emergency demands quicker response from the redundant bladder. Either way, using a redundant bladder necessitates a lot more practice and instinctive reaction...

Others consider it 'best practice' to not even use a dual/redundant bladder wing. This is especially true of GUE divers, who prefer a 'balanced rig' (GUE 'Balanced Rig' video link)...

Balanced Rig
The DIR rig is a carefully weighted rig; one that ensures that while a diver is not overweight, s/he is able to hold a decompression stop in the face of a catastrophic gas loss. This requires a careful assessment of the component parts of one's configuration, and how these each impact-statically and dynamically-on the buoyancy characteristics of the configuration as a whole.

Whilst I am not a GUE diver, I was 'converted' to this mindset by speaking to one of their instructors (Gideon Lieu) after several years of diving with a dual bladder wing (Custom Divers TDB). I now dive a Halcyon Evolve. When I used a dual bladder wing, I had one hose feeding the LPI... and my drysuit hose could be transfered onto the redundant LPI/bladder if needed. Basically... I had 2 LPI hoses that could run either of the inflators and my drysuit.

 

[Ste Wart]

Some consider it 'best practice' to not actually connect the second LPI to the inflator though... as the risk of air accidentally leaking into the redundant bladder could post a dangerous runaway buoyancy threat on ascent. Other will argue that a buoyancy emergency demands quicker response from the redundant bladder. Either way, using a redundant bladder necessitates a lot more practice and instinctive reaction...

A few years back Don Shirley was visiting the dive centre I was working at. He spied a friends DIR rig i.e Single Bladder and Drysuit. He enquired as to why he dived that Rig and the usual answer was given. Don then he replied that he always dived a twin bladder regardless as he like to come back from his dives alive. A bit harsh on my friend, but right up my IANTD alley.