FR2618352A1 - Device for multistation stirring in a thermostatic medium - Google Patents

Abstract

It consists of a vessel 1 containing the heating fluid 2 thermostatted at 3. Part 4 strengthens the vessel and holds the motor-carrier plate 5 and the receptacle-carrier plate 6. The motor 7 and the measuring electrode 8 are positioned on the motor-carrier plate. The stirring device 9 and 10 is driven by an independent motor. Support of the receptacle 11 is ensured by a ring seal 12. A leakproof compartment 13 above the receptacles makes it possible to produce a controlled atmosphere 14, 15, 16. The device according to the invention is particularly intended for laboratories which need to treat series of liquid samples at controlled temperature, rate of stirring and atmosphere.

Description

 The present invention relates to a multi-station stirring device in a thermostatic medium usable in the laboratory.

 Equipment of this type has become essential for laboratories (biochemistry, petrochemistry, food industry ...) which process series of samples.

Indeed, the simultaneity of the treatment on multi-user allows among other advantages, an obvious time saving.

Among the devices currently on the market, we can distinguish the stirring systems by blade and by magnet bar. Agitation by blade is certainly the most efficient, but its difficult implementation (movement from a single motor, transmitted and distributed by means of belts or gears) limits its field of application. agitation by magnetic bar is on the contrary of an easy implementation but its performances are inferior, for example it becomes inoperative in the case of viscous liquids
In addition, the stirring device by magnetic bar, imposes by its very principle that the bottom of the container containing the liquid 9 to be stirred and to be thermostated rests on the drive motor. As a result, the circulation of the heat transfer fluid is not uniform over all the walls of the container, hence the appearance of a temperature gradient which may be deemed unacceptable by the user.

 The device according to the invention overcomes this dilemma since it combines easy implementation and superior performance. I1 indeed has a simplified stirring system since each blade is surrounded by an independent motor and hanging containers such that the container / heat transfer fluid interface is maximum. The device is multi-user in the sense that it has n stations. Each station being constituted by at least one independent stirring motor placed above a container immersed in a heat transfer fluid common to all of the n stations. It should be noted that for a large surface container, several stirring motors can be used. The electric motors used in the device are characterized by the fact that they are produced in large series for the automotive industry which gives them a low cost price, proven reliability and performances which have been concealed, particularly suitable for agitation in multi-user stations. For an identical shape and dimensions, they can be chosen from a range comprising several rotational speeds. Interchangeability and adaptability to user needs are thus ensured Reduced dimensions (diameter 4 cm and height 6 cm ) and the low price. that this type of motor is not a limiting factor for the arrangement and the number of stations in a thermostatic tank. The axis of rotation of each vertically positioned motor is directly coupled with the rod comprising the stirring blades. The motor assembly is supported by a removable plate forming the cover of the tank.

This plate also supports the measuring instruments such as probes, electrodes ... etc relating to each station. The receptacles receiving the stirring blades are supported by a removable plate, parallel to the previous one, adjusted to the internal walls of the tank and fixed to the latter by cleats
According to a preferred embodiment, each container almost entirely immersed in the heat transfer fluid is maintained at the desired height by the only pressure exerted against its walls by a seal integrated in the support plate. The seal is chosen so that it can oppose the buoyancy or the weight of the container while allowing easy handling of the latter. The containers are indeed removable and interchangeable. In addition, the two plates, support engines and container support, constitute with the walls of the tank a sealed compartment allowing to achieve a controlled atmosphere above the containers.

 According to a variant, the container support plate and the containers themselves can be made up in a single piece which can be made of rigid transparent plastic or stainless steel.

 Figure I shows, in section, the device according to the invention.

 Figures 2 and 3 show, respectively in section and top view, an example of multi-station equipment made from the device according to the invention.

 The device shown in Figure 1 includes a tank (1) containing the heat transfer fluid (2) whose temperature between -10 and + 60'C is regulated by a circulating or immersed cryothermostat in (3). The part (4) is a cross which connects in the direction of the width the two opposite walls of the tank.

While allowing the free circulation of the heat transfer fluid, this cross member improves the rigidity of the tank and ensures the maintenance of the engine support plate (S) and the container support plate (6). The sealing of the passages of the motor axis (7) and of the measurement electrode (8) through the motor support plate is ensured by leprosy or O-rings. The positioning of the motor and the electrode on the preceding support plate is facilitated by imprints of corresponding shapes. A sleeve (9) allows the coupling of the motor axis with the rod comprising the stirring blades (10).

 Maintaining and adjusting the height of the container (11) is ensured by an O-ring (12) housed in a groove in the container support plate.

Between the previous support plates. the walls of the tank and the crosspiece is made up one. sealed compartment (13) making it possible to produce a controlled atmosphere above the container. This atmosphere can be formed by a gas (oxygen, nitrogen ...) or a gaseous mixture (air 95X and carbon dioxide 3% ...) which apyres having been brought to the temperature of the bath by crossing a flexible pipe (l4) immersed in the heat transfer liquid enters (15) in the sealed compartment and exits in (16).

The device shown in Figures 2 and 3 is indicative and not limiting an example to illustrate the invention. The components of the tank with a thickness of 1 cm are made of polymethyl methacrylate The external dimensions of the tank, expressed in cm are: L 72.1 = 28 72. 1 - 28 and H = 18
The cryothermostat used is immersion, it regulates the temperature of the heat transfer fluid (glycol water) in a range between -10 and + 60 ° C. The containers used are commercial beakers with a diameter of 60 mm and a crystallizer with a diameter of 130 mm. The O-rings have a slightly smaller diameter respectively 39 and 129 mm. The fifteen motors shown in Figure 3 are PHILIPS motor-reducers mounted in molded plastic housing resistant to chemical agents and corrosion These motor-reducers with 24 V power supply , provide reduced speeds at the axis output, thanks to a reduction gear integrated in the housing. Thus the speeds are in revolutions per minute: 330 for the nine motors located on the right, 60 for the three motors located in the lower left and 8.2 for the three motors arranged in a triangle. These engines were originally intended for the automotive industry (rotating lights, headlight wipers, electric antennas, positioning of exterior mirrors, etc.). The device shown in Figure 3 therefore has thirteen positions.

 The device according to the invention is particularly intended for test, control and research laboratories which must process series of liquid samples under temperature. perfectly determined stirring speed and atmosphere. Compared to commercial equipment, designed for the same field of application, it is characterized by simplicity of implementation, adaptability to the needs of the user and performance limited only by the capacities of the cryothermostat.

 According to a variant. the device according to the invention can be transformed into a sterile mini incubation chamber, suitable for cell cultures for example. This application is made possible by the controlled atmosphere of the sealed compartment. In this case, just use PEIRI bowl type containers

Claims (5)

Claims 1- Multi-station stirring device in thermostatic medium characterized in that it comprises in its upper part a sealed compartment (13) delimited by a plate (5) supporting the stirring motors (7) and the measuring instruments ( 8) and a plate (6) holding the containers (il) in the suspended position, the plates (5) and (6) themselves being supported by the walls of the tank (1) and the crosspiece (4). 2 - Device according to claim I characterized in that each container (11) is held by the only pressure exerted against its walls by a seal (12) integrated in the plate (6) 3- Device according to claim I characterized in that 'To each container (11) corresponds an independent and interchangeable stirring motor (7). 4- Device according to claim 1 characterized in that the plates (5) and (6) are removable and interchangeable. 5- Device according to claim 1 characterized in that the sealed compartment (13) allows to achieve above the containers a controlled atmosphere. 6 - Device according to claims 1, 2 and 4 characterized in that the containers (11) are removable and interchangeable. 7 - Device according to claims 1, 2, 3, 4, 3 and 6 characterized in that it can constitute a sterile mini incubation chamber using PEIRI type dishes as containers.  s - Device according to any one of the preceding claims, characterized in that the plate (6) and the containers (it) can constitute a single piece. available in rigid transparent plastic or stainless steel.