Although it’s not immediately apparent on the deck plans, there are bulkhead doors at all access points between decks, including in the lift shaft
Bulkhead doors normally remain open, but when they decide to close, they don’t care what’s in the way
Individual bulkhead doors will close when anyone tells them to (a break glass kind of affair)
All bulkhead doors will close
Under any of these conditions, the lift shaft will also be completely filled with vacu-seal foam, which is a pain in the arse to clean out, but better than losing all your air
Bulkhead doors can only be opened using crew codes (centrally or individually). As always, the captain’s codes override other crew
Hull breaches will be repaired with vacu-seal foam as a first defence
Any fire on board will cause surrounding bulkheads or doors to close and the affected room/s to be flooded with fire-retardant foam. The foam subsides fairly quickly, and it’s unusual for anyone who’s still ambulatory to be suffocated by it
The usual protocols indicate that any unauthorised breach of quarantine (when quarantine conditions are declared) will result in ALL doors and bulkhead doors closing and locking. They can only be opened with crew codes. Air conditioning will also shut down for as long as possible, and when it returns, will be compartmentalised.
Most systems have redundant backups, but there is no automatic repair system. Repair bots can be retrofitted, but they’re about the same cost as the ship herself