DIR- Generic Doubles Gas Management?

[buildhuntcook]

I am newly interested in moving into back-mounted doubles and looking into the different systems. I have talked with several advanced technical as well as cave divers and I have a newby question about how the gas is managed on a set of back-mounted twin cylinders. Everyone in my local area uses a long hose configuration, i.e. GUE/UTD/ISE with a manifold. I went to a PADI shop looking into tech courses as they are the only ones that offer technical courses in my area (the advanced divers in my area were trained elsewhere) and now I am really confused about how to breathe from back-mounted doubles. From what I can gather the manifold is open all of the time and the tanks are breathed down as if they were one big tank with a really large volume. The primary regulator stays in the mouth all of the time. If there is an issue then the appropriate response to find/shut down the problem is addressed. The PADI guys I talked to described using the back-mounted doubles basically as two independent systems and requiring redundant EVERYTHING. They described breathing down each tank 500 psi and then switching regulators and leaving the manifold closed and shutting off each tank. Is this the correct method according to PADI? I feel like this defeats the purpose of the manifold being able to share gas with each regulator. The introduction of redundant everything in my mind would make it much harder to find a problem. If you have a redundant bladder in your BC and it auto-inflates then the diagnosis is more steps than knowing your bc is inflated from just your right post. I asked what they did in the event of a buddy being out of gas and having to donate if the valve was shut every time they switched and they said you turn it on. If there is an event on the regulator you are breathing from then equalizing the pressure across the manifold introduces high pressure at depth that could potentially cause more problems. Am I just way overthinking this? Is this the PADI approach to technical diving? Again I am new to this journey and I just want to feel confident about the place I am going to seek training. Any advice or experience is greatly appreciated.
Thanks in advance

 

[tbone1004]

Doubles are traditionally treated as one large tank. Isolation is done in extremely rare circumstances *rare to the point that I haven't heard a report of someone having to isolate in over a decade*.

Independent doubles are sometimes used and those are treated like sidemount tanks for gas management however that is also extremely uncommon.

 

[grantctobin]

I am newly interested in moving into back-mounted doubles and looking into the different systems. I have talked with several advanced technical as well as cave divers and I have a newby question about how the gas is managed on a set of back-mounted twin cylinders. Everyone in my local area uses a long hose configuration, i.e. GUE/UTD/ISE with a manifold. I went to a PADI shop looking into tech courses as they are the only ones that offer technical courses in my area (the advanced divers in my area were trained elsewhere) and now I am really confused about how to breathe from back-mounted doubles. From what I can gather the manifold is open all of the time and the tanks are breathed down as if they were one big tank with a really large volume. The primary regulator stays in the mouth all of the time. If there is an issue then the appropriate response to find/shut down the problem is addressed. The PADI guys I talked to described using the back-mounted doubles basically as two independent systems and requiring redundant EVERYTHING. They described breathing down each tank 500 psi and then switching regulators and leaving the manifold closed and shutting off each tank. Is this the correct method according to PADI? I feel like this defeats the purpose of the manifold being able to share gas with each regulator. The introduction of redundant everything in my mind would make it much harder to find a problem. If you have a redundant bladder in your BC and it auto-inflates then the diagnosis is more steps than knowing your bc is inflated from just your right post. I asked what they did in the event of a buddy being out of gas and having to donate if the valve was shut every time they switched and they said you turn it on. If there is an event on the regulator you are breathing from then equalizing the pressure across the manifold introduces high pressure at depth that could potentially cause more problems. Am I just way overthinking this? Is this the PADI approach to technical diving? Again I am new to this journey and I just want to feel confident about the place I am going to seek training. Any advice or experience is greatly appreciated.
Thanks in advance

Mind posting the shop and instructor name?

 

[formernuke]

As stated above. Plus....
For tech classes don't do PADI. I don't know who wrote there tech programs but he or she was definitely smoking something.

It is worth traveling to get a good tech instructor.

If all the other tech divers in your area are traveling for certs, there is a reason.

 

[Robert H. Diver]

Yea don’t do tech with padi.

 

[Whitrzac]

Padi isn't the problem here, its the instructors outdated thinking.

 

[buildhuntcook]

Mind posting the shop and instructor name?

There are only a few shops in my area and this shop is associated with the sheriff's department so I would rather not. Lol.

 

[buildhuntcook]

Padi isn't the problem here, its the instructors outdated thinking.

That is why I was asking if this is a PADI thing. I am not biased toward any organization and I was willing to give them a chance but it seems like his thinking is the opposite of everything I have learned on my own. I received a lot of crazy looks when I described how I understand the system to be designed and was met with "have YOU ever dived on a set of doubles?".

 

[buildhuntcook]

As stated above. Plus....
For tech classes don't do PADI. I don't know who wrote there tech programs but he or she was definitely smoking something.

It is worth traveling to get a good tech instructor.

If all the other tech divers in your area are traveling for certs, there is a reason.

My only options for tech training as of now are this local PADI shop(which is not looking like an option), traveling nine hours to Tennessee for a UTD instructor, or five hours for an independent TDI instructor. My local SSI shop is looking into adding XR courses but no one knows anything about them so far. Of these options what do you think would be the best course? The UTD instructor basically said to train with UTD but teach elsewhere if you are looking to be an instructor. I just want to have a solid foundation. I grew up diving in Guam and literally just got certified a month ago because I don't have access to a compressor anymore. I learned that some of the stuff I grew up with is incorrect. I understand the importance of training and being certified now. I also learned that there is a large population of divers that can't tell you how much gas they need for a dive without their air-integrated computers.

 

[Robert H. Diver]

My only options for tech training as of now are this local PADI shop(which is not looking like an option), traveling nine hours to Tennessee for a UTD instructor, or five hours for an independent TDI instructor. My local SSI shop is looking into adding XR courses but no one knows anything about them so far. Of these options what do you think would be the best course? The UTD instructor basically said to train with UTD but teach elsewhere if you are looking to be an instructor. I just want to have a solid foundation. I grew up diving in Guam and literally just got certified a month ago because I don't have access to a compressor anymore. I learned that some of the stuff I grew up with is incorrect. I understand the importance of training and being certified now. I also learned that there is a large population of divers that can't tell you how much gas they need for a dive without their air-integrated computers.

Call the TDI instructor and talk to them…conduct an “interview” and see if you like their teaching style. It’s important especially for tech classes that you mesh with your instructor.