ventilation

Good evening, I recently read an article from 1911 that talks about the ventilation on the titanic, we talk about portholes with automatic ventilation. Can anyone tell me more? In the porthole in the photo there are two "valves" above, does anyone know what they are for...

Reviewing the deck plans, specifically the boat deck, I became curious about the section between the char/pilot rooms and officer's lavatory. Specifically, the Nos 5&6 Boiler Casing, Fidelity, and Trunk|Vent portions. I have tried searching for those terms but am unable to get much information...

Regarding the dust that resulted from coaling ship, would there be any way at all the effect could be mitigated? Would ventilation throughout the vessel be stopped and doors all be closed in accommodation? I imagine it would be a nightmare if dust got into places like the á la carte restaurant...