The 3000 Series control valve provides accurate control of gases, liquids, and slurries for linear or equal percentage flow, says the manufacturer. The valve is equipped with a characterized plate designed with two standard openings — slotted and V-style. Standard plate angles are 30, 60, and 90 degrees. Custom-designed plates with other angles or slots are available. The valve offers high- and low-flow control and excellent repeatability, the company says. It is available in 1/4- through 4-in. sizes. Marwin Ball Valves, 3170 Wasson Rd., Cincinnati, OH 45209; 800-628-2583; 513-533-7340; 513-533-7343 (fax).