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.