This post is for educational and informational purposes.
Context:
During a training dive in almost 30 meters on a sidemount regulator switch, we had a gas denial/interruption coming from one tank!
Being that the regulators were fresh out of the box, we went through a process of elimination with the seller of the regs but had no definitive answer as to how this could happen. After thinking it through, it came down to a simple pinched hose.
To be fair, a quote from the manufacturer's manual on this particular hose model:
"Never over-flex your hose. Never fold the hose back onto itself. If your hose is too long, you may loop it and secure it in place with a section of rubber tubing (such as the inner tube of a bicycle tire). However, the minimum bending radius must be at least 3.5 times the outer diameter of the hose. For example, if the outer diameter of your hose is 12mm, then the minimum bending radius (as measured to the inside of the hose) is 42 mm."
These little incidents, however, can easily escalate into much more complicated outcomes. Good thing that the user had the proper training, and presence of mind to deal with it. Being aware of this as a possibility, particularly true with the variance in hose quality out there and their unique characteristics, may prevent incidents like these from happening in the first place.
Learn more about InnerSpace Explorers training here: @CoastalDevelopment