Aeris 750GT - Good idea?

[suncoast]

I'm planning on buying a dive computer within the next 3 months.
I like the idea of air-integrated computers.

I'm going to be buying double Nitrox tanks and will need to get
dual regulator setups, separate for each tank with connecting
DIN valves.

My thinking was to have two SPGs, good for redundancy. Here's
my new thoughts...

Instead of two SPG consoles, how about simply having the Aeris
750GT with two transmitters? One transmitter for each tank.
If one tank needs to be shutdown for whatever reason, I still
have the second tank and use of the 750GT via the transmitter on
that tank. I know I lose the redundancy of another console, but
having multiple computers gets pretty expensive.

Any thoughts on this?

Thanks!
Steve (diver and off-roader)
Long Island Off-Road Vehicle Association

 

[TexasMike]

My initial thought is if you are diving with doubles, then you are diving in the "Technical" realm, and from what little I know, what you are proposing is not the best of ideas.

First, I don't think any hoseless computer can accept input from two transmitters at the same time without getting confused. In otherwords, how will it or you know which tank is being reported? And if you were to shut down one post, then that transmitter would read almost zero and the computer might report an out of air situation.

Second, I think the best thing for you based on the info you provided is to go with a simpler rig of a real good and solid SPG (such as the OMS brand) and a good tech diving computer such as the Dive-Rite Nitek3.

I've seen the setup I described on a few tech divers I had a chance to meet in North Carolina and they both were very satisfied with their setup.

Perhaps some of the other Tekies here (Lost Yooper, L_D, Roakey, Blacknet, etc) might have some more ideas for you.

 

[suncoast]

The two tanks are connected together via a bridge valve (forgot what they are called). When both tanks are open, they work together feeding either one or two set's of regulators. As you breathe, both tanks get depleted together. Being there is a bridge between them, they maintain equal amounts of air/nitrox. You can isolate a tank by simply turning the valve off for that tank. Then you breathe off the other tank alone. This wouln't be done unless there is a problem with a tank, such as a leak.

I'm not 100% sure about what happens at the first stage of the tank that is shut down. Does it still get air from the other tank or is it shut down totally? If it gets shut down totally, then I can understand your issue regarding one transmitter sending an out of air signal vs. the other sending a signal showing psi still available in the open tank. Also, both transmitters will transmit on the same frequency, so there isn't a mixup there. The problem would show itself if the first stage mounted to the bridge at the shutdown tank doesn't receive any psi from the open tank (I think I explained this correctly.)

Anyone have any idea about this?

 

[suncoast]

Well, I found the answer to one of my questions. The so called "bridge valve" I mentioned in my previous post is called a Manifold...

I found a link that explains how the manifold works. The link is here: Dual tank Manifold

Basically, I can use the dual transmitters but I cannot use the isolation valve on the maifold if I do. That will defeat the purpose of what I was trying to accomplish. Of course, I cannot do what I was thinking about anyway. The isolation valve is there for a purpose, to shut down and isolate a faulty regualtor and/or tank.
If I chose to ignore the isolation valve in a situation like that, well then I don't value my life very much (I do, but my ex doesn't )

I guess I'll stick with the dual consoles...Redundancy just may save my life one day and I'll be glad I did it!

Sometimes, all it takes is one person to question one's reasoning to provoke additional thought and research.
Thanks TexasMike!
:idea:

 

[randyjoy]

Another point: to switch the computer (receiver) to a different transmitter requires switching into Set mode, which is only available above water, then setting the link ID to the other transmitter. Complicated above water.

 

[suncoast]

I think you can buy an additional transmitter that operates on the same frequency as the first. That way they both are in sync, no switching.

Anyway, I've decided that's NOT the way to go.

Thanks for your input!

 

[JamieZ]

Just to clarify something about isolation manifolds. When you close the valve down on one of the tanks, you are not shutting that tank down but you are shutting the reg down that is on that tank. To isolate the tank you would have to shut down the isolation valve, which like you stated would shut down both the reg/tank.
I personally have never seen a setup like the one your talking about but (no flame intended) think its a bad idea and a waste of money. Go with 1 pressure gauge and 2 regs and a bottom timer. If your pressure gauge fails or any of your equipment that would be a good sign to abort the dive. When diving doubles you should also know your SAC rate which will tell you how long your gas should last when you work that figure into your tables. If you feel that you need a computer I personally like the Cochran Comander 2 gas nitrox version.
Please seek the training you need before switching to doubles not because of the double tanks but because of the extra time it will give you down there. If you were to take basic courses like the Adv. nitrox and a Decompression course they will teach you gas management which will include out of air situations under the direct supervision of instructor in case you couldn"t manage to turn your valves back on after they just shut them off with out you looking. Good luck with your quest for knowledge.

 

[suncoast]

Scubanarc, thanks for your input. It's greatly appreciated from all that replied.

I definately plan on taking the Adv. nitrox and a Decompression courses. I'm currently finishing my Rescue Diver and will begin my Divemaster next week. I'm going to work on gaining more dive experience for a while and then continue with the Adv. nitrox and Decompression courses this Summer.

I won't be doing the double tanks until after the Adv. Nitrox course anyway. By then I will have saved enough money to do it the "right" way.

Again, thanks for all input!

Happy diving!