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IAPMO PS 54-2021a
Industry Standard for Metallic and Plastic Utility Boxes
This Standard covers utility boxes intended for plumbing applications (e.g., washing machines, ice makers, tubs, gas appliances, and air admittance valves) and made of (a) acrylonitrile butadiene styrene (ABS); (b) polystyrene (PS); (c) polyvinylchloride (PVC); (d) steel; or (e) a combination of the materials listed in Items (a) to (d). This Standard specifies requirements for materials, physical characteristics, performance tests, and markings.
International Association of Plumbing and Mechanical Officials [iapmo]