Hugh, I am not sure exactly what you are speaking of when you mention the bubble line and Comsub. If you are referring to naval sub escape ops then yes, air has to be added to maintain the air bubble sufficiently large to breath from. Can’t remember exactly but the bubble line should be about at the top of where the sloped escape tube mates with the sphere (or now cylinder) that comprises the escape chamber. Flooding/draining and air pressure can be controlled from outside of the escape chamber on a naval sub. R/Jay Resepectfully, Jay K. Jeffries Andros Is., Bahamas Save the whales, collect the whole set. From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Hugh Fulton According to the formula for a 2” valve for 75% of the volume was 16.3 seconds to the bubble line and as it is not ambient inside when you reach bubble line, but then the next step is to “BLOW” which I assume is blow air into it to approximately equalize then “EQUALISE” If you haven’t frozen by that time. Some of the previous comments are that air trapped inside is a problem when you open the hatch. I was hoping to have that clarified by those with practical knowledge. I was impressed with the Comsub as it has two 2” valves in it which I assumed were for flooding but then I found that they led into the hydraulic motor compartment????!!! Chs, Hugh |