Abstract: The method comprising the steps of engaging the flow circuit of the detector with a reference fluid, accepting a sample in the flow circuit of the detector, sensing an attribute of the sample for determining a characteristic of the sample, changing the direction of the flow of the sample in the flow circuit, and purging the sample from the flow circuit such that the flow circuit is ready to accept another sample. Another method provides the steps of engaging the flow circuit of the detector with a reference fluid, inserting a sample in the flow circuit juxtaposed to the reference fluid, sensing an attribute of the sample for determining a characteristic of the sample, and deviating the direction of the flow of the sample from the flow circuit for purging the sample from the flow circuit such that the reference fluid is maintained in the flow circuit.

Abstract: This apparatus and method relates to the improved sensing of fluid differential pressures. The apparatus and method can be applied in multi-capillary solution viscometers and gel permeation chromatography systems used in the characterization of polymers. A valve is used to alter a flow path in a measurement circuit to reduce or eliminate an undesired fluid output and to accelerate the regeneration of the fluid for analysis of subsequent samples. The apparatus and method can be usefully applied to all instruments and systems comprising viscometers having two or more capillaries.