Jaap
Thanks for the info, I was beginning to think my question was too newbie in nature! When I wrote escape I meant that this one was originally designed to escape from tanks that had stalled as a result of their snorkel breaching when they crossed rivers! - a frightening experience I'm sure!
I shall read the other threads as well and I will definetley look at disconecting the T piece inside the lung. I also noticed that inside the scrubber there is a bulkhead to separate the two sides do you think initially this was to contain O3 on one side and sodalime on the other .. or just for flow properties.
Thanks for the help
James