I’ve used yellow hoses for deco bottles. I’ve also used yellow hoses for stage bottles, and I’ve even used a yellow longhose/primary. I think I’ve also used green and gray hoses, and of course, black. One of my stage/deco 2nd stages is yellow, currently on a black hose. I also have a black 2nd stage currently on a yellow hose.
The hose is designed to allow gas to travel from the 1st stage to the device’s 2nd stage, inflator mechanisms, or spg, and the 2nd stage is designed to deliver gas to the diver at slightly above ambient pressure. The color of the hose and/or 2nd stage has nothing to do with the purpose they serve, nor do they serve as any kind of identifier. Let’s look at some of the reasons why:
First, switching to the wrong gas can quickly kill you. More than one person has died because they were breathing an incorrect gas at depth. The gas switch is a critical point in a technical dive, and a mistake can quickly become tragic. Due to the opportunity for severe consequences, we use very specific procedures and protocols for switching from one gas source to another. This includes identifying the bottle (for more information, see our Deco Bottle Marking Page), confirming its contents, identifying/confirming the regulator attached to the bottle, and verifying current depth. This is all done in a very specific & logical sequence, and hose & 2nd stage color adds no useful purpose to that process.
Next, a regulator can serve multiple purposes. It may serve different purposes on different dives on the same day. For example, my criteria for choosing a deco/stage regulator for a given dive is the length of time I’ll be using that regulator on the dive. I have a favorite deco/stage regulator, and I prefer to use that regulator on the bottle I’ll be breathing the longest. On a dive that I’m using both a stage and deco bottle(s), I may use it on the stage that I’ll breathe down. The next dive, I may use it on my 70′ bottle, and the next dive my O2 bottle. If hose and 2nd stage color were part of the identification process, that regulator would be inflexibly dedicated to a single specific role, or, I’d have to switch out the hose and/or 2nd stage between dives, if the regulator was changing roles/functions.
Another reason color coding doesn’t work in our diving is we operate on a “next reg up” or “next hose up” method. Meaning, on technical dives, cave/mine/wreck dives and exploration projects we have extra, backup regulators and hoses in the save-a-dive kit. If there’s an issue with a reg or hose in the pre-dive check, we simply grab another regulator or hose and go. Having a regulator dedicated to a specific function according to hose or 2nd stage color doesn’t afford us the flexibility of using a regulator for whatever purpose it’s needed for. This becomes especially important on projects in remote locations with limited resources.
Looking at the above, there is a real opportunity for color coding to actually cause confusion in our diving. Imagine performing our gas switch protocol, confirming the bottle and 1st stage, but with an incorrect hose color, because the regulator was actually put on a bottle it wasn’t intended for. In our diving, it makes no difference, as we simply confirm the bottle and regulator. If hose color played a role, at best we’d now have confusion that we need to sort out, at a point in the dive that needs to be performed and completed efficiently and smoothly. Is it the correct bottle, with wrong hose, or the correct hose, but on the wrong bottle? At worst, the diver goes to the wrong gas, because he switched to the gas based on the hose color. He’s now in jeopardy of DCS, as he’s breathing the wrong decompression gas and not decompressing as intended/believed, or worse, oxygen toxicity, if he’s too deep for the gas he just switched to.
Want more info on our equipment configuration, including deco/stage regulators? Visit our Equipment Configuration Page.