______ pipe and fittings shall not be used unless specifically listed with the system.

• A. Copper
• B. PVC
• C. Stainless steel
• D. Galvanized

Answer: (D)

Materials used for piping in a wet chemical fire suppression system must be specifically listed for compatibility with the system and the agent. Galvanized pipe and fittings are generally not acceptable unless the system listing explicitly approves them, because the zinc coating can be attacked by the wet chemical (potassium acetate), leading to corrosion, contamination, and potential failure of the piping. The listing process ensures that the material, its coating, and its installation are proven to withstand the agent and operating conditions. Copper, stainless steel, and PVC are often used when the system listing confirms their compatibility, but they must be specified by the manufacturer for that particular installation.