Laboratory thermostat

United States Patent Application 20040216862

A laboratory thermostat features a heating and/or cooling device for temperature control of a liquid bath medium located in a bath tank. The laboratory thermostat has an early-warning system with a control device for a low liquid level in the bath tank and an evaluation device that can realize at least an acoustic and/or visual warning message for maintaining the temperature control process. Due to the integrated early-warning system, when the liquid level decreases, the user of the laboratory thermostat is made aware in due time before undesired shutdown by a low-liquid-level protection device, so that lost temperature control fluid can be immediately refilled before the safety shutdown is triggered by the low-liquid-level protection device.

Jucheim, Gerhard (Seelbach, DE)

10/818245

11/04/2004

04/05/2004

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Julabo Labortechnik GmbH (Seelbach, DE)

165/11.1

B01L7/02; G01F23/60; (IPC1-7): F25B49/00; F28F1/00

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NORMAN, MARC E

Volpe Koenig (PHILADELPHIA, PA, US)

1. Laboratory thermostat with a heating and/or cooling device for temperature control of a liquid bath medium located in a bath tank, comprising an early-warning system with a controller for a low liquid level in the bath tank, and for maintaining a temperature control process, an evaluation device that provides at least one of an acoustic and a visual warning message.

2. Laboratory thermostat according to claim 1, wherein a response threshold of the early-warning system lies above a response threshold of a low-liquid-level protection device.

3. Laboratory thermostat according to claim 1, wherein the control device has a float (10) connected to an electrical switching element (12) and the electrical switching element (12) is connected electrically to an acoustic warning element for generating the acoustic warning.

4. Laboratory thermostat according to claim 1, wherein a pulsed warning message is provided through at least one of an acoustic warning element and a control lamp (18).

5. Laboratory thermostat according to claim 1, wherein an interface (21) is provided with a connectable cable for remote, external monitoring of the warning function.

6. Laboratory thermostat according to claim 1, wherein a circularly arranged keypad (14) and VFD info display (15) are provided.

[0001] The invention relates to a laboratory thermostat with a heating and/or cooling device for controlling the temperature of a liquid bath medium located in a bath tank.

[0002] Laboratory thermostats are used for high-precision temperature control and maintaining of an adjustable temperature value. The main functional elements are the heater, circulating pump, and control electronics. A bath tank is used to store the temperature-control liquid. Water, bath oil for higher temperatures, or alcoholic fluids for negative temperatures are used as the temperature-control medium.

[0003] Laboratory thermostats can be used both for internal temperature-control tasks in bath tanks and also for external temperature control of a load with the help of an integrated circulating pump. Here, the main application in science and research and also in many fields of industry is temperature control of external measurement and analysis system instruments, reaction systems, and measurement cells in a temperature-control cycle.

[0004] Here, there can be fluid losses due to evaporation of the used bath medium or due to breaks in seals in the external circuit.

[0005] If there is a low-liquid-level protection device, these losses would definitely lead to shutdown of the system.

[0006] However, the shutdown of the system can create problems in the treatment. For example, for an internal temperature control of bacteria cultures in a bath tank, there is the risk that these bacteria cultures are irrevocably destroyed by a sudden shutdown of the temperature control process. Furthermore, for external processes, the interruption of the temperature control can have the effect that the entire process must be repeated with corresponding expense.

SUMMARY

[0007] The object of the present invention is to create a laboratory thermostat of the type mentioned above, which can prevent problems due to premature, undesired shutdown of the laboratory thermostat by means of the low-liquid-level protection device.

[0008] To achieve this object in accordance with the invention, the laboratory thermostat has an early-warning system with a controller for low liquid level in the bath tank, and that for maintaining the temperature-control process, an evaluation device is provided at least for an acoustic and/or visual warning message.

[0009] Due to the integrated early-warning system, when the fluid level decreases, the user of the laboratory thermostat is made aware in due time before the undesired shutdown by a low-liquid-level protection device, so that the lost temperature-control fluid can be immediately refilled before the safety shutdown is triggered by the low-liquid-level protection device.

[0010] Additional configurations of the invention are noted below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In the following, the invention is explained in more detail with reference to the drawings with their essential details.

[0012] In the drawings:

[0013] FIG. 1 is a side view of a laboratory thermostat with early-warning system with certain areas cut away,

[0014] FIG. 2 is a front view thereof, and

[0015] FIG. 3 is a rear view of the laboratory thermostat shown in FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] A laboratory thermostat shown in the figures has control/safety electronics 5 with a controller for a low liquid level in the bath tank and also an evaluation device at least for a visual and/or acoustic warning message.

[0017] Furthermore, a temperature sensor 6, a heater 7, an immersion pump 8 with external pump attachments 9, and a float 10 with electrical switching element 11 are preferably provided. These elements can be used to trigger a shutdown function, especially a safety shutdown.

[0018] The novel early-warning system has another switching element 12. The control/safety electronics 5 include a signal buzzer 13 for a pulsed acoustic signal release. These electronics are electrically connected to the switching element 12 and the switching element 11, which triggers a shutdown function with continuous signal tone.

[0019] The early-warning system is integrated in the heating/cooling thermostats (FIG. 2) and also in circulating coolers with a circularly arranged keypad 14, a VFD info display 15, a network switch 16, an adjustable high temperature protection device 17, and a visual display of warning and safety functions 18.

[0020] On the rear side (FIG. 3), there are connections for a Pt100 external sensor 19, a refrigeration control 20, and an interface 21, over which an early warning function can be transmitted to the outside.