It's usually not like in the movies that when one sprinkler goes off, the entire building is getting a shower. That's only for high risk installations.

Usually it's just one in the fire area, they trigger with a heat sensitive capsule that breaks.

Do apartment buildings count as high risk? Genuine question

Anyway if I remember my highrise fire safety training right there is at least one building where on sprinkler going off sets the others off. IIRC the pressure drop from one unit activating triggered a pump and the subsequent increase in pressure popped the other.

Perhaps you’re thinking of how the jockey pump and main pump work together in a sprinkler system.

A jockey pump maintains pressure in the system and is sized at less than the flow rate of one sprinkler head. The main fire pump is activated when a pressure transmitter detects a drop in pressure. The jockey pump can’t maintain pressure when a sprinkler head opens, and the drop in pressure starts the main fire pump.

No they don't. Only industrial places like storage of flammables or high-dust that can cause explosions.

Of course it would be quite annoying to have your apartment flooded because one of the neighbours let their pizza burn :P

Cool, thank you for clarifying!

A burning pizza just kicks off the fire alarm, not the sprinklers. Frankly I don't remember much past the the whole drop in pressure detection leading to kickoff of other sprinklers thing to suggest what level of partitioning occurred .