Boiler Room 4 was the third boiler room, between Boiler Room 5 and Boiler Room 3. These boilers were connected to the 2nd funnel.
Sinking[]
At 12:10, the order to draw the fires had been given in Boiler Room 4 an 5.
At 12:35, in Boiler Room 4, the water was about 16 inches above the floor plates at the forward bulkhead. The firemen in the forward area now left the rising water would shortly save them the trouble of having to douse the fires.
At 12:45, the water in Boiler Room 4 would have started flowing aft into the tank-top of Boiler Room 3.