Abstract: The invention is a system and process for pumping fluids in lines, comprising using, on the lines, a pump with at least two alternating fluid pumping units. Each pumping unit (PU1, PU2) comprises a cylinder (2) and a piston (1) alternately displaceable in the cylinder under the action of a power source (M), under the control of a control device (PC), with, for both pistons, imposed displacement functions (f(t), g(t)) suitably phase-shifted in relation to one another so as to obtain a first operating mode corresponding to substantially constant delivery rate. This pump is operated in the same circuit according to the complementary second operating mode corresponding to a substantially constant intake rate by inversion of the direction of displacement of the pistons so as to apply to the pistons displacement functions (−f(t), −g(t)) symmetrical to those corresponding to the first operating mode.

Abstract: The invention relates to the measurement of the difference between refractive indexes of two media, traversed by a light beam the beams produce an interference figure consisting of fringes having a displacement which is measured.According to the invention, the displacement of the fringes of the interference figure is detected with a photosensitive device and a phase modulation is performed on at least one of the beams and the modulation is controlled in order to obtain a movement of the fringes of the interference figure.

Abstract: The present invention relates to a system for generating the same instantaneous pressure between two tanks filled each with a given medium, the first tank including at least one inlet channel and at least one outlet channel for the given medium, the second tank including at least one outlet channel, and means for opening and for closing said channels. The system according to the invention further includes at least one linking capillary between each tank, intended notably for transmitting instantaneously a pressure variation from the first tank towards the second tank.

Abstract: Chromatograph in high performance liquid phase comprising a monochromatic light source emitting a beam which, after splitting, is divided into two parallel beams which go respectively through two cuvettes, the one containing a reference liquid, the other the measurement liquid. The two beams on coming from the cuvettes go into a detection unit. After splitting, each of beams R, M is divided into a system P with a semireflecting surface SR, a part going into one of the cuvettes CR, CM and being reflected by the rear of the cuvette forming a mirror MC to come back to semireflecting surface SR along a reverse path, the other part of the beam coming to be reflected on a mirror MR, at right angles to each beam, moved by a piezoelectric device PZ.

Abstract: A liquid phase chromatography apparatus consists of a tubular column which is intended to receive a charge of powdery adsorbing solid material and which comprises porous plates at its ends, one of these plates being fastened there and other plate being able to move inside the column under the action of a jack and thus to compress the charge in the column. This apparatus is characterized in that charge (5) is contained in an interchangeable rigid or semi-rigid cartridge (4) with an outside diameter approximately equal to the inside diameter of column (1), the latter being cut into two equal half-cylinders (2) which are brought together after insertion of said cartridge (4) and which are kept clamped together by any suitable means (3).

Abstract: The present invention is a liquid pumping system with constant flow rate. The system contains at least one first cylinder means and reciprocating piston means defining a first pumping capacity (V.sub.1), at least one second pumping unit including cylinder means and reciprocating piston means defining a second pumping capacity (V.sub.2) and at least one complimentary pumping unit including cylinder means and reciprocating piston means defining a complimentary pumping capacity (V.sub.0) the driving means for actuating the piston means synchronously but in phase opposition between the piston means of the first unit and the second and complimentary pumping units in such a manner that each piston performs alternating suction and discharge strokes linearly having feed lines and check valves wherein V.sub.1 equals V.sub.2 plus V.sub.0.

Abstract: In a chromatographic column assembly comprising a tubular column a first end of which is sealed, the second end of said column is also sealed in order to form an enclosure between said second end and a piston. A pressurized fluid introduced into this enclosure displaces the piston in the direction corresponding to compression of a packing or filling provided in the column. A flexible conduit ensures the circulation of a fluid to be chromatographed and crosses through the piston, the enclosure containing the pressurized fluid and the second end of the column.