The Varian PrepStar SD-1 Digital Solvent Delivery Module with 500 TI Pump Heads is an innovative HPLC solvent delivery system engineered with preparative chromatographers in mind. A powerful drive unit and dual interchangeable pump heads provide pumping capacity to 3.2 L per minute at pressures of up to 2.6 MPa (375 psi) for superior throughput with large high-resolution microparticulate columns. For bench-scale prep, 200 mL per minute and 50 mL per minute heads provide flow at pressures up to 41.4 MPa (6000 psi) and 68.9 MPa (10,000 psi), respectively. Corrosion-resistant titanium pump heads address the needs of biochemists for compatibility with salt-containing buffers and freedom from unwanted metal ions. Each pump head has a piston washing chamber to prevent deposition of abrasive salt residues behind the high-pressure seal, thereby greatly extending seal life.