Agilent 1100 Quat Pump (G1311A). It ensures virtually pulse-free and stable solvent flow, with dual floating pistons in series, precisely servo-controlled. Setable Flow Range: 0.001 – 10ml/min – in 0.001ml/min increments. Flow Range: 0.2 – 10.0 ml/min. pH Range: 1.0 – 12.5, solvents with pH > 2.3 should not contain acids which attack stainless steel. Formation: Low pressure quaternary mixing/gradient capability using proprietary high-speed proportioning valve. Delay volume 800-1100µl, depending on back pressure.