This standard covers the various types and classes of cold-water displacement meters with plastic main cases, in sizes 1/2 in. (13 mm) through 1 in. (25 mm), for water utility customer service, and the materials and workmanship employed in their fabrication. The displacement meters covered, known as nutating-disc or oscillating-piston meters, are positive in action because the pistons and discs displace or carry over a fixed quantity of water for each nutation or oscillation when operated under positive pressure. The main purpose of this standard is to provide purchasers, manufacturers, and suppliers with the minimum requirements for cold-water meters—displacement type, plastic main case, including materials and design.