What type of sprinkler heads can be used in environments with temperatures below 40 degrees Fahrenheit?

Dry sprinkler heads are specifically designed for environments where temperatures can fall below 40 degrees Fahrenheit. The key feature of dry sprinkler heads is that they are filled with pressurized air or nitrogen instead of water. This prevents water from entering the pipes and freezing, which could otherwise lead to pipe bursts and system failures in cold environments.

When the temperature drops and reaches a certain trigger point, the dry sprinkler head activates by allowing the gas to escape, which then enables water to flow from a supply line. This design is particularly effective in unheated spaces such as attics, warehouses, or any area susceptible to low temperatures.

Wet sprinkler heads, on the other hand, are filled with water and are therefore not suitable for freezing conditions, as the water could freeze and obstruct the system. Pre-action and deluge heads also involve water but in a different context; pre-action systems require a secondary triggering mechanism, while deluge systems release large amounts of water at once for fire suppression. Neither of these options is appropriate for protecting areas that may be exposed to freezing temperatures.