A single-capillary viscometer (SCV) used as an on-line viscosity-sensitive detector for size exclusion chromatography (SEC) presents considerable interest. Unfortunately, the commercially available version, which uses a traditional HPLC pump and a pulse dampener, presents serious problems and can give poor performance. Flow rate fluctuations are the main problems in the use of the on-line SCV detector. The pulse dampener resolves the flow fluctuations problems that are intrinsic to a reciprocating pump. Unfortunately, the pulse dampener introduces secondary, yet variable, flow fluctuations that make the SCV unreliable. In the past, several solutions to the problem have been described. Our proposal is to use the SCV on-line detector with a new commercial pulse-free pump without a pulse dampener. A detailed evaluation of this new SEC-SCV system has been performed using Various polymers. Molar mass distribution, intrinsic viscosity distribution, and constants of the Mark-Houwink-Sakurada relationship have been determined. The used polymers were soluble both in organic solvent (PS, PMMA, PVAc, PVC, polyalkylthiofene) and in aqueous solvent (PEO, PEG, pullulan, and hyaluronan). The results obtained are encouraging.