Diaphragm-type pre-pressurized expansion tank specifically designed for potable hot water systems. These tanks control water pressure build-up and eliminate relief valve spillage caused by thermal expansion when water is heated. 3/4" Male pipe thread connection. Requires no maintenance. Required by code in many counties and states. Use model No. 993-024 for self-piercing valve. Specifications: Models G5, G5L, G12, G12L; Maximum allowable working temperature: 200 deg. F.; Standard factory precharge: 40PSIG (Relief valve must be set at 150PSIG). Maximum pressure maintained at least 10% below relief valve setting (150PSIG); Models are listed with IAPMO (International Association of Plumbing and Mechanical Officials) and SBCCI (Southern Building Code Congress International); Models are NSF (National Sanitation Foundation) Listed for liner only.