Which piping material is not permitted for clean agent system piping?

Which piping material is not permitted for clean agent system piping?

• A. Cast-iron pipe
• B. Copper pipe
• C. Nonmetallic pipe
• D. Steel pipe conforming to ASTM A120

Answer: (A)

Material compatibility and mechanical integrity of the piping are what this question tests. Clean agent systems require piping that can resist chemical attack from the agent and maintain a tight, leak‑free seal under system pressures and over time. Cast-iron is not suitable for this environment because it is prone to corrosion and brittle joint behavior with many clean agents, increasing the risk of leaks or failure. Copper, steel that meets the relevant standard, and approved nonmetallic piping provide better corrosion resistance and reliable joints, which is why they are allowed.

Material compatibility and mechanical integrity of the piping are what this question tests. Clean agent systems require piping that can resist chemical attack from the agent and maintain a tight, leak‑free seal under system pressures and over time. Cast-iron is not suitable for this environment because it is prone to corrosion and brittle joint behavior with many clean agents, increasing the risk of leaks or failure. Copper, steel that meets the relevant standard, and approved nonmetallic piping provide better corrosion resistance and reliable joints, which is why they are allowed.