To prevent freezing, you must install a Dry Pipe Sprinkler System or a Pre-Action System. In these systems, the pipes inside the -18°C storage room are filled with pressurized air or nitrogen, not water. A dry pipe valve outside the cold zone holds back the water. When a sprinkler head shatters due to heat, the air pressure drops, opening the dry pipe valve, and allowing water to flow into the room. This ensures no water sits inside the cold room during normal operations.