These days those systems are locked out when people are working in there. Not so much in the old days :-) I worked at palace (based at Cranfield uni) that ha

These days those systems are locked out when people are working in there. Not so much in the old days :-) I worked at palace (based at Cranfield uni) that had an experimental rig that used freon as a working fluid - we had emergency respirator sets (like the fire service uses) and people trained in them to use to rescue anyone.