Clarifications on fire sprinklers

Question

1. how much litres per minute does each sprinkler head spray

2. what is the average pressure requirement for a sprinkler pump. After making some calculations on a system with 15 sprinklers, it showed me that there needs to be a pressure of around 20 bars for it to work

3. when the pump is pumping the water into the pipes, what's stopping the pipes from overflowing. is there a drainage where the unused water goes back to?

Answer 1

1. Your sprinkler head specs will determine the flows & pressure required at the sprinkler head to obtain that flow.
2. Your local fire codes or insurance company will tell you the total flows required and where (like inside pallet racks for some items, etc.).
3. Wet sprinklers stay closed by a device that shatters when hot, letting the water out. Dry sprinklers work when the water is turned on. Dry systems would have a drain for when you're done.
4. Regular pipe head loss calculations apply. In the US, only calcs by a licensed Professional Engineer will suffice for such things.
5. Pump sizing comes from the required flows & pressure.