Abstract: To provide a degassing unit having a wide range of flow speed, high-efficiency compactness in size, this degassing unit consists of both a degassing module composed of a gas permeable flat-shaped tube 201 wound around the internal vacuum space 401 and a vacuum chamber containing this flat tube, and by flowing an eluent through the flat tube 201 which constitutes the degassing module, gaseous components dissolved in the eluent can be transpired from the flat tube 201 to the vacuum chamber accommodating the internal vacuum space 401 and the external vacuum space 402 and 403, thus being well removed.

Abstract: A solvent delivery pump assembly for use in high performance liquid chromatography systems, which accurately delivers a solvent (eluent) drawn from a reservoir, and having removed gases, dissolved in the eluent, and then delivering the eluent as desired for analysis. The apparatus comprises two pump units, each with two plungers of different diameters on a single shaft; one of the plungers in one of the pump unit is of a large diameter size for driving a first pump head in large volume, and the other plunger in the other pump unit is of a smaller diameter for driving a second pump head in small volume.