If you dive rebreathers much, chances are you will have to repair or replace the Molex plugs and pins that connect your Teledyne R22D oxygen sensors to your head electronics. Many manufacturers are cool about sending you the parts so that you can do the repair yourself, but some, such as AP Diving require that you send the entire head back for this simple repair.
If you are comfortable handling electronics, and you think it’s silly to have to send your head all the way to England or wherever just to have a couple of parts costing less than $1 replaced, you can get the parts you need from just about any distributor that sells electronic components. I like Digi-Key because they would sell me the crystals to make a Red Box when nobody else would. I’ve been loyal ever since.
With the help of my friend in Reno, I was finally able to get my gas blending system together and working. This system will allow me to connect nearly any type of industrial gas cylinder to any type of SCUBA or medical oxygen tank. I can even connect it up directly to banks of 4500 PSI air.
When building these systems, many people decide to incorporate quick disconnects at the supply side to facilitate quick changes in gas for making custom blends. This allows for the adaptor to stay connected to the industrial gas cylinder, while making it easy to move the whip from gas to gas. This is a great design in theory, but these connectors tend to develop leaks over time, which can be frustrating and costly, especially when working with helium.
In order to maintain the flexibility of quick disconnects without the problem of leaky connections, Keith had the brilliant idea to standardize the entire system on SCUBA DIN connectors. This makes switching source gas nearly as easy, but results in a much more solid and leak-proof connection. A male DIN connector is at each end of the fill whip, and all bulk cylinder adaptors have a female DIN connector on the whip side. Connecting up your source gas becomes as easy as screwing in your SCUBA first stage.
In the interest of being thorough, I decided to get the system with just about every type of cylinder adaptor imaginable. For the time being, I really only plan on doing transfils from industrial gas cylinders for my gas blending, but at some point I may decide to hook it up to a booster. My rebreather tanks are only 20 cf, so I can’t really justify the cost at the moment, but if I ever start making TRIMIX in anything larger, I will have to invest in some type of booster to make the helium go further.
Everyone likes Richard Pyle, and we all wish we had is uber sweet CIS Lunar rebreather, but I have to say this video of him down below 100M swearing like a sailer in that Donald Duck voice that you get with a larynx full of helium is pretty darn funny!
The cool thing about rebreathers is that you can talk into them, and people can understand you. Sure, if sounds like you have a mouth full of rubber (which you do), but you can still be understood. I’m guessing that these guys found a pretty serious thermocline, and the water got a great deal colder than they anticipated.
Pyle is clearly disturbed by this unfortunate turn of events, and spends quite a lot of time swearing and complaining about the cold water. I guess we can’t really blame him for not piling on the thermal protection though. He was, after all off Christmas Island in the Central Pacific Ocean. It’s only five degrease north of the equator, so the water should, in theory, be pretty warm.
I will never suggest that a person refrain from messing around with something because it is dangerous. I have always held the belief that given proper respect for the lives of those around them, people should be left free to do their best, or worse as the case may be.
That being said, this article about a diver who, while filling scuba tanks, more or less burned his house down with an oxygen fire really shows us why it is important to be careful when handling high pressure oxygen.
I guess this guy was blending NITROX and the line caught fire. He wasn’t able to get the tank shut down before the whole place went up in flames. From what the article tells us, he was blending the gas himself because he didn’t hold a cert for it, and couldn’t buy it at dive shops. I guess he’d also been known to boost steel tanks up to 4500 psi with pure oxygen.
There are a lot of people out there holding this as an example of why nobody should be blending their own gas. I think this mindset is ridiculous! I frequently blend my own NITROX and TRIMIX, but I’m constantly mindful about the presence of hydrocarbons and adiabatic heating. I can’t say I would boost pure oxygen to 4500 psi, but there is absolutely no reason that divers can’t safely handle high pressure oxygen and blend their own gasses.
Because many of the dive sites I love require travel, and because a full-blowen technical diving expedition for open circuit diving requires a sometimes prohibitively large volume of helium and pure oxygen, I made the decision some time ago to get into rebreather diving.
Many of the people I dive with have been using them for some time now, and as a result many of the technical trips are targeted at rebreather divers only. This largely left me out in the cold because there was never enough helium and O2 around for me to do many serious dives.
The only question was which rebreather to buy. I flirted briefly with the Inspiration (Yellow Box Of Debt), but it’s harness system didn’t really fit my needs, and you need to get the vision electronics package to really make it cool. This will set you back $10,000, and it still requires a number of modifications to really make the unit sing.
I really like the PRISM Topaz by Steam Machines. It has a really nice radial scrubber, and the fact that you can still read the secondary display even with a total electronics failure is a huge bonus. Ultimately I decided against it though, because I didn’t like the idea of using only the Heads Down Display for my primary instrumentation.
In the end, the ISC Megalodon won out because of its very solid feature set. It has two nice readable displays as well as a Heads Up Display. It is made out of aluminum rather than plastic, and the cylinders are solidly mounted to the unit with Tiger Gear hard mounts. This makes the system extremely modular as you can use any cylinders you like. It is also nice that my dive buddies are using them.
My unit will be ready for me in late February, and I will be taking the training from Leon (ISC CEO) directly.