1.187.089 Blast doors are not airtight anymore
I know the airtightness is experimental. In the current version (new game no mods) the blast doors are not airtight anymore.
1) build a cubic room lets say 10x10x10 with light amor blocks
2) put a vent into the wall and connect it to an oxygen tank
3) well have some power on the grid
4) the room should now have oxygen in it - check - worked
5) now make a 3x3 hole into the wall and exchange it with a 3x3 blast door on a piston
6) retract and revert the piston (optional)
6) now the room is not airtight anymore (it was in the last versions though)
Not sure if this is a decision made by you or considered a bug. This also means small grid airtightness is not possible anymore because you have no doors to enter the grid (makes the small air vent obsolete)
Would be nice if you could say how you think it should work.
I hope this helps a bit