I find it a bit cumbersome to create airlocks, as well as it being greatly affected by lag.
I propose a couple blocks, that when placed together, interact like an airlock.
A player would interact with a door of the airlock, and it would pressurized to match the requested side. Then it would open, then the player would walk into it, and interact with the other door. Then it would close the first door, and then pressurize to the second side's pressure.
I feel it could be intelligent enough to know which side of a door is being interacted, in order to know if a player is wanting to leave the airlock, vs enter it and take the correct action.