Which material should not be used for piping in a wet sprinkler system?

In a wet sprinkler system, the primary concern is to ensure the piping can reliably carry water under pressure without risk of failure, particularly in fire suppression scenarios where heat and water are present. PVC (Polyvinyl Chloride) is not suitable for this application because it is sensitive to temperature fluctuations and can become brittle when exposed to heat. The integrity of the piping is crucial since sprinkler systems must function effectively under the extreme conditions that accompany a fire; if the piping were to become compromised, it could lead to system failure during a critical time.

On the other hand, materials like copper, steel, and aluminum are commonly used in wet sprinkler systems due to their durability, resistance to heat, and capability to handle the pressures required in fire protection applications. Copper and steel, in particular, can withstand high temperatures and provide reliable performance, while aluminum also offers benefits like lightweight and corrosion resistance, albeit with some limitations when it comes to high-temperature applications. Therefore, PVC's weaknesses in relation to fire and pressure make it an inappropriate choice for piping in a wet sprinkler system.