Final answer:
To prevent freezing, wet pipe systems must maintain water above the freezing point of 0°C (32°F), typically at a minimum of 4.4°C (40°F). Sublimation, the phase change from solid to gas without becoming liquid, is a process that occurs in substances like water and carbon dioxide under different pressures.
Step-by-step explanation:
The question is about the minimum temperature at which water in a wet pipe system should be maintained to prevent the system from freezing. While the precise temperature was not provided, keeping water in building wet pipe systems above the freezing point of water, which is 0°C (32°F), is essential to prevent freezing. In general practice, maintaining a temperature marginally above freezing, such as 40°F (4.4°C) or higher, is advisable to provide a buffer and ensure the system does not freeze, even when temperatures fluctuate.
It's important to prevent sublimation, which is the transition from solid to gas without passing through a liquid phase. This principle is critical for understanding how substances like water and carbon dioxide transform under different pressures. For water, sublimation occurs under very low pressures, while carbon dioxide sublimates at 1 atm.
To prevent the risk of freezing and subsequent damage to the wet pipe system, the system should be kept at temperatures consistent with the building's heating capabilities and the local climate.