Probably a home-brew. One major problem with a simple manifold of valves is cross-contamination of different mixes, especially without check valves. Let’s say you have a 9% deep mix online and one of the valves on a rich decompression gas leaks into the manifold. Your PPO2 could jump from 1.0 to 4 without knowing it. It is equally dangerous on decompression. You could go hypoxic or get bent.
Better-designed commercial mixed gas manifolds (in the gas shack) have a vent valve between the stop and check valves. This ensures that any leakage vents safely to atmosphere rather than contaminating the online gas with an inappropriate mix. Most operations also have an oxygen monitor on what's going down the hose to guard against operator error.
Better-designed commercial mixed gas manifolds (in the gas shack) have a vent valve between the stop and check valves. This ensures that any leakage vents safely to atmosphere rather than contaminating the online gas with an inappropriate mix. Most operations also have an oxygen monitor on what's going down the hose to guard against operator error.