Waters 600 HPLC Gradient Module Pump. An HPLC pump component designed for reliable chromatography injection, featuring a stainless steel flow path and Watersâ€™ Auto Blend function. For use with the Waters 600 HPLC Controller. Number of Solvents: 1 to 4. Modes of Operation: Gradient, isocratic and flow programming. Pump Head Volume: 100 Âµl. Maximum Pressure: 5000 psi (351.5 kg/cm2). Operating Flow Rate: 0.1 to 15.0 ml/min. Flow Range: 0.00 - 20 ml/min (standard 100 ul heads), in 0.01 ml increments. Compositional Accuracy: < Â±0.5% (pressure independent).