Fer fooooks sake Mr Draeger.... This is a fine germanic lesson in how to engineer something to be as bloody overcomplicated as possible.
I was tempted to add a 1l o2 bottle to this and some cells in the head of the scrubber as a (very) poor mans CCR but sod that. Taking it to bits to clean the counterlungs out just took me nearly 30 minutes. Yeugh.
On the other hand the DSV and hoses will work a treat on something else that's on the way...