Wet pipe systems must maintain water at a minimum temperature of what to prevent freezing?

To prevent freezing in wet pipe sprinkler systems, it is crucial to maintain the water temperature above 40 degrees Fahrenheit. This temperature threshold is based on the physics of water freezing; at 32 degrees Fahrenheit, water begins to freeze solid, which can lead to substantial damage within the sprinkler system. If water freezes in the pipes, it can cause blockages, pressure build-up, and potentially burst pipes, rendering the fire protection system inoperable. Therefore, the maintenance of water above 40 degrees Fahrenheit offers a safety buffer against freezing, ensuring that the system remains functional even in colder environments. This is a key consideration for the design and maintenance of fire protection systems, particularly in areas prone to low temperatures.