Regulator and Air Integration Question for Doubles/Twinsets

[mikecotrone]

Hi,

I am learning and honing my skills on my single rig setup at this time, however I am academically still learning from your experiences on double/twin-set kit setup. I have two questions if you could shed some light on for me.

1. Do you use Octo's with Doubles? I assume no since you have a built in redundant first stage off of your isolator manifold along with your other second stage. If you got into a 1st/second stage failure on the one side then you could isolate it off to only use your working 1st/2nd. Are Octo's even used in Doubles?

2. Air Integration - Currently I have two dive computers that are both air integrated and I have one transmitted on my singles kit. It works great transmitting to both computers no issues. If you move to doubles then you now have two 1st stages to deal with. Does that mean you double up on transmitters and then now having two live computers (one for one transmitter and the other for the second transmitter) vs. a redundant pair? Or do you only use one transmitter on one 1st and thumb the dive if something happens on the transmitter? Or do you not use Air Integration with doubles?

Sorry for the possible dumb questions, but I began to think about this during lunch and figured I would ask vs. guessing.

Thanks!

 

[Jimmer]

I have 4 hoses total on my doubles regs.

Right Post:
First stage with 7 foot hose to my primary second stage.
Wing inflator hose.

Left Post:
Short hose with backup second stage bungeed under my chin.
24" HP hose to a single brass and glass pressure gauge.

If my buddy needs an "octo" I remove the one in my mouth, pass it to him, and place the one under my chin in my own mouth. No electronic pressure gauges for me, but I dont see a problem with it if someone wanted to use one as a backup. I would put the transmitter on the right post reg in that case.

Jim

 

[DevonDiver]

1. Do you use Octo's with Doubles? I assume no since you have a built in redundant first stage off of your isolator manifold along with your other second stage. If you got into a 1st/second stage failure on the one side then you could isolate it off to only use your working 1st/2nd. Are Octo's even used in Doubles?

There are no 'rules' about configuration - but most tech divers opt for a Hogarthian set-up. This is under-pinned by a risk assessment to determine the need for redundancy.

They don't use octos because there is very little chance of both divers developing simultaneous faults. One diver would need to have no available gas and the other diver would need to have a simultaneous failure on one of their hoses, for an extra octo to be required. Given the redundancy that already exists (manifold doubles) and the level of training that the divers should possess, then this is a very remote likelihood.

To balance that (and retort any possible 'more is better' debate), the divers' configuration choice also takes account of the increased chance of failure by adding complexity and 'failure points' into the system. An extra regulator/octo would constitute a major 'failure point'.

On balance, it is agreed that the likelihood of the need for an extra octo is hugely outweighed by the likelihood that the octo could cause problems by its inclusion within the system.

2. Air Integration - Currently I have two dive computers that are both air integrated and I have one transmitted on my singles kit. It works great transmitting to both computers no issues. If you move to doubles then you now have two 1st stages to deal with. Does that mean you double up on transmitters and then now having two live computers (one for one transmitter and the other for the second transmitter) vs. a redundant pair? Or do you only use one transmitter on one 1st and thumb the dive if something happens on the transmitter? Or do you not use Air Integration with doubles?

It depends. If you are diving a manifolded set of doubles, then there is no real benefit from having that redundancy. You are essentially breathing from 'one big tank' unless you had a tank valve failure that required you to shut-down the manifold. As before, the risk inherent with adding a further HP hose and gauge/computer to your rig will outweigh any benefit of having that integrated gauge redundancy.

On balance of risk vs benefit, the typical tech diver will use a single, basic SPG attached to their left 1st stage.

Alternatively, if you were diving independant doubles, then you would require a dedicated SPG/computer for each cylinder/1st stage.

Most technical divers don't opt for AI gauges, but again, there is no 'rule' against it (outside of the DIR fraternity).

 

[mikecotrone]

There are no 'rules' about configuration - but most tech divers opt for a Hogarthian set-up. This is under-pinned by a risk assessment to determine the need for redundancy.

They don't use octos because there is very little chance of both divers developing simultaneous faults. One diver would need to have no available gas and the other diver would need to have a simultaneous failure on one of their hoses, for an extra octo to be required. Given the redundancy that already exists (manifold doubles) and the level of training that the divers should possess, then this is a very remote likelihood.

To balance that (and retort any possible 'more is better' debate), the divers' configuration choice also takes account of the increased chance of failure by adding complexity and 'failure points' into the system. An extra regulator/octo would constitute a major 'failure point'.

On balance, it is agreed that the likelihood of the need for an extra octo is hugely outweighed by the likelihood that the octo could cause problems by its inclusion within the system.




It depends. If you are diving a manifolded set of doubles, then there is no real benefit from having that redundancy. You are essentially breathing from 'one big tank' unless you had a tank valve failure that required you to shut-down the manifold. As before, the risk inherent with adding a further HP hose and gauge/computer to your rig will outweigh any benefit of having that integrated gauge redundancy.

On balance of risk vs benefit, the typical tech diver will use a single, basic SPG attached to their left 1st stage.

Alternatively, if you were diving independant doubles, then you would require a dedicated SPG/computer for each cylinder/1st stage.

Most technical divers don't opt for AI gauges, but again, there is no 'rule' against it (outside of the DIR fraternity).

Thanks for clarifying Andy. I myself will be diving using the Dive Rite 300 bar DIN Isolator Manifold and I will not be diving independent doubles at this stage of the game. However I do love the redundancy options this setup provides you.

 

[RJP]

I dive with a transmitter on the right post and an SPG on the left. (Don't tell my DIR friends.) This way, should I need to isolate the manifold I can still read accurate pressure on whichever tank I'm still breathing.

 

[nelsondejesus]

I dive with a transmitter on the right post and an SPG on the left. (Don't tell my DIR friends.) This way, should I need to isolate the manifold I can still read accurate pressure on whichever tank I'm still breathing.

Same here, for the very same reason

 

[Jim Lapenta]

The thing to remember is if there is a failure and you have to shut down one post and close the isolator the dive is over. I don't use ai computers at all. Couldn't afford one when I started and see no need for one now. I have heard of divers putting an spg on each post with manifolded doubles but that seems like an unnecessary thing to do. If your primary fails you close the isolator and shut down the post. Some will say close the post first but whatever one you shut down you are now on your backup where the spg is anyway. As far as the transmitter goes I'd make sure it is in such a position that it is not in danger of getting knocked. Again not using ai I've never encountered the issue, but could two transmitters that close interfere with each other? An spg won't. And transmitters are what a couple hundred bucks? An spg and hose is way less and doesn't need batteries that can fail.

 

[halocline]

If you're planning on learning to dive with doubles in the hogarthian set up, you might try a modified hogarthian set up on your single tank. That would be a 5 foot hose on your primary, 22-24" for the secondary (bungied), and a 24" hose SPG. I'm pretty sure when/if you get into technical dive training the use of the AI computer will be frowned on in those settings, so buying the SPG now and using it in addition to your AI on your single tank will not be a waste of money. Neither will the hoses; you can simply transfer them to your doubles set up, and when/if you get into training overhead situations and a canister light you can buy the 7 foot hose. At that point I would bet you'd like the long hose enough to put the 5 footer back on your singles and use it. The 5 and 7 foot hoses rout the same way and offer similar benefits for streamlining and air sharing, it's just that the 7 ft allows you to share air single file in constricted areas, and is typically routed under a canister light on your right hip.

So, eventually, you'll have a pretty similar set up for the doubles and single, just different length long hose and no AI on the doubles. Personally I like that in my own diving a lot. I don't like the 'normal' recreational routing any more, in fact I find it pretty uncomfortable compared to the long hose.

 

[RJP]

As far as the transmitter goes I'd make sure it is in such a position that it is not in danger of getting knocked.

With my regs (AL Legend LX Supremes) the transmitter points down and is parallel to the tank neck. It is oriented in a such a way that it is "in-board" of the valve handle, valve, and tank, so it's not at significant risk of knocking anything or being entangled.

 

[Scott]

I dive with a transmitter on the right post and an SPG on the left. (Don't tell my DIR friends.) This way, should I need to isolate the manifold I can still read accurate pressure on whichever tank I'm still breathing.

I used the same setup during my initial training.
I found it helpful to use AI so I could compare what I calculated my SAC rate at based on the SPG versus what the computer calculated.

It will be your rig, dive it how you would like. The greatest concern would be the position of the transmitter. If your reg setup can position the transmitter downward or parallel to the neck I see so issues. If it is in a position to get bumped, mistaken for a post or cause entanglement you may want to reconsider.

One work around that I have seen is use a short myflex hose and secure the transmitter between the cylinders near the neck area.