In which type of system would you find open sprinkler heads constantly?

In a deluge system, you would find open sprinkler heads that are constantly exposed, which differentiates it from other types of sprinkler systems. In this type of system, all the sprinkler heads are left open and are typically used in areas where the risk of fire is high, such as warehouses that store flammable materials. When a fire occurs, the detection system activates, releasing water through all open sprinkler heads simultaneously.

This design allows for a larger volume of water to be discharged quickly at the onset of a fire, effectively suppressing flames over a wide area. This is particularly important in scenarios where controlling fire spread is critical, as it provides a comprehensive approach to fire suppression rather than relying on individual sprinkler heads.

In contrast, wet pipe systems have closed sprinkler heads filled with water, which only activate when the heat from a fire melts the fusible link or breaks the glass bulb. Dry pipe systems also contain closed heads, but they are filled with air and use pressurized air to hold back the water until a fire is detected. Foam systems utilize foam agents and typically do not have open heads either. Therefore, the unique characteristic of the deluge system with its always-open heads is what makes it the correct answer in this context.