Pipe and associated fittings shall be of ________ material having physical and chemical characteristics compatible with the wet chemical solution.

• A. non-combustible
• B. flammable
• C. plastic
• D. conductive

Answer: (A)

Noncombustible material is required because the piping and fittings must not provide fuel for a fire and must withstand exposure to the wet chemical solution. The Class K wet chemical system uses a caustic potassium acetate–based liquid that can be corrosive and is discharged with heat and pressure, so the piping needs to be noncombustible to avoid contributing to a fire and to remain structurally intact under service conditions. Additionally, the material must be chemically compatible with the solution to prevent corrosion or reactions that could cause leaks or failure. Stainless steel and other noncombustible metals are typical choices that meet both the fire-safety and chemical-compatibility requirements.