EP1616155A2

EP1616155A2 - Safety device for laboratory work, especially for liquid chromatography systems

Info

Publication number: EP1616155A2
Application number: EP04722518A
Authority: EP
Inventors: Thomas Maetzke
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-04-22
Filing date: 2004-03-23
Publication date: 2006-01-18
Also published as: WO2004095017A2; WO2004095017B1; WO2004095017A3; CH696214A5; US20060261964A1

Abstract

The invention relates to a safety device (1) for laboratory work, especially for fluid chromatography systems. Said safety device comprises a level measuring arrangement (7) which is connected to a tank (8) and generates an alarm signal upon detection of a certain liquid level in the tank (8). According to the invention, the level measuring arrangement (7) is also connected to at least one laboratory working surface (3, 4) and also produces an alarm signal when liquid is detected running over the at least one laboratory working surface (3, 4). Preferably, the level measuring arrangement (7) is connected to a monitoring device (31) embodied as a power supply unit, said monitoring device containing a plurality of safety circuits and introducing a time-delayed circuit interruption when an alarm is generated by one of the safety circuits.

Description

Safety device for laboratory operation, especially for liquid chromatography systems

The invention relates to a safety device for laboratory operation, in particular for liquid chromatography systems according to the preamble of claim 1.

The invention is particularly suitable, but not exclusively, for use in the field of high-pressure liquid chromatography (HPLC) or in the field of medium-pressure liquid chromatography, where the discharge of volatile, highly flammable and toxic solvents, which occur there in larger flow rates, for example at 100 ml / min be pumped, must be avoided.

For example, a dishwasher is known from EP 0 333 251 A2, which is provided with an overflow pipe for limiting the liquid level in the machine, the overflow pipe being equipped with a siphon-like part. The siphon-like part has an inverted U-shaped curvature in the overflow pipe.

From FR 2 776 381 A1 a device for displaying the fluctuation in the liquid level of liquids provided in a container is known. The device comprises a float which can move up or down in a tube. The float is connected to a magnetic body, which can move back and forth in a second tube. With the second hose, magnetic contacts are provided at the desired heights. As soon as the magnetic body comes close to these contacts, an alarm signal is triggered.

US 6 276 200 B1 describes a control system for a liquid level in connection with a swimming pool. This system has a sensor which is attached to a holder. The sensor is able To send signals. When the liquid level changes, a feed valve can be activated or deactivated by the signals sent, which feeds replacement water to the swimming pool.

A system for controlling a separation unit for the multiphase separation of liquids is known from WO 01/43867 A1. In this system, a level of one or more liquids in the separation unit is set in relation to a reference value. The reference value and the liquid level converted into a pressure are led to a pressure-sensitive, mechanical device, the movement of which is transmitted directly to a mechanical control unit. This is coupled to a monitoring device.

A disposal system for liquid waste materials at a laboratory work station is known from EP 1 106 254 A2. This disposal system comprises a receptacle which is assigned to the laboratory work station and / or a laboratory work table and has an inlet for the waste materials, a suction connection and a ventilation closure. A mobile collection container is provided for the purpose of better disposal of the waste materials. A fill level monitoring device is assigned to the receptacle, which activates an optical or acoustic signal when the waste materials in the receptacle reach a predetermined fill level. For this purpose, the monitoring device has a sensor which is held on the outside by a holder in a specific position relative to the receptacle and which generates a control signal or triggers the signal when the specific fill level is reached. The sensor can be, for example, an effector or an ultrasonic sensor. A signal generated by another filling level monitoring device can serve to display the filling level and / or for an operational planning that takes into account the time for which the capacity of the liquid container, such as a large container, is still sufficient. For this purpose, the latter monitoring device has a float, the respective height of which is decisive for the respective signal output. According to this document, as mentioned above, one or more sensors can be provided, which physical parameters, for example pressure, temperature or concentration of the Measure waste, in the container and, if necessary, trigger an alarm using an alarm device or generate a signal to switch off an associated pump. A suitable sensor can be connected to the pump via a signal line, so that the delivery is switched off if a condition for the waste material in the collecting container is not fulfilled, for example if the maximum filling level is reached or an undesired chemical reaction takes place.

The invention has for its object to provide a safety device of the type mentioned, which is more versatile.

According to the invention, this object is achieved by a safety device having the features of patent claim 1.

Advantageous further developments are the subject of the dependent claims.

In the safety device according to the invention, a fill level measuring arrangement is preferably provided in the form of a barrel adapter with a siphon, which adapter is screwed onto a liquid container and in which a fill level sensor is inserted. According to a preferred embodiment, the barrel adapter has two inlets, which lead directly into the liquid container designed as a waste container, and an inlet, which leads into the siphon and is connected to at least one laboratory work surface, so that liquid leaking out on the at least one laboratory work surface can be detected early, ie before the entire liquid container is full, and an alarm signal can be generated. The fill level measuring arrangement designed and arranged according to the invention is thus able, in the sense of a double action, to detect both the liquid level in a liquid container, such as a solvent container, and leaked liquid and, accordingly, also to send or trigger an alarm signal in the latter case. Thus, one and the same level measuring arrangement can serve at least two different purposes, as a result of which its area of use is significantly expanded. The fill level measuring arrangement according to the invention can thus be used for Detection of a certain liquid level and / or for the detection, for example, of liquid spilled on a laboratory work surface. This can trigger an alarm signal when the liquid container is full or when, for example, a solvent is collected from a laboratory work surface.

According to an advantageous development, the fill level measuring arrangement, namely preferably the aforementioned barrel adapter, has a siphon-like interior, for example, into which liquid can flow from a certain liquid level in the liquid container and / or on the at least one laboratory work surface, and which a fill level limit switch, preferably an Vibration limit switch, is assigned. The siphon-like interior can therefore be used to hold different liquids, namely the liquid from a liquid container and a leaked liquid. The level limit switch determines whether there is liquid in the interior and can then trigger an alarm signal regardless of where the liquid comes from.

According to another development of the invention, the fill level sensor protrudes from above into the siphon of the barrel adapter, which preferably has in a side wall of its interior a through hole connecting the interior of the liquid container with the interior of the siphon of the barrel adapter. The entire level measuring arrangement consisting of barrel adapter with siphon and level limit switch in turn protrudes from above into the liquid container. As a result, liquid can then easily enter the interior of the fill level measuring arrangement, namely the siphon, when the liquid in the liquid container has reached a certain fill level. The through hole thus acts like a kind of overflow.

According to a preferred development, the level measuring arrangement, namely the barrel adapter, has a cup-like element, which preferably has a thread on its upper side with the lower end of a longitudinal bore of the main part of the Level measuring arrangement, namely the barrel adapter, is screwed, wherein said main part preferably has an additional bore opening into this longitudinal bore, through which liquid running out on a laboratory work surface can flow into the interior of the level measuring arrangement. The cup-like element, also called a siphon, thus collects the leaked liquid, so that the area of application of the level limit switch, which, as mentioned above, is assigned to the interior and thus to the cup-like element, is expanded. This can therefore detect leaking liquid at an early stage. With the help of the screw connection between the cup-like element and the main part of the barrel adapter, the cup-like element can be easily emptied, so that it and thus the entire level measurement arrangement is ready for use again after a short time. With the help of the additional bore of the barrel adapter, a simple possibility is created to connect the fill level measuring arrangement on the one hand to the location where a liquid can escape, in particular overflow, and on the other hand to direct the liquid escaping there to the interior of the cup-like element, where even small quantities Liquid can be detected. The safety device according to the invention is therefore able to detect even small amounts of liquid and to generate an alarm signal at an early stage.

According to another development, the fill level measuring arrangement is also a barrel adapter. This can be provided with a G2 inch standard thread and thus forms with the level limit switch a universal level measurement arrangement for overfill prevention of liquid containers, for example waste containers, preferably in liquid chromatography. The barrel adapter is preferably made of metal (such as, for example, stainless steel or aluminum) or of an inert plastic and screwed onto the liquid container, in particular a waste container for liquid substances. The safety device according to the invention can thus be connected to numerous liquid containers and can therefore be used within wide limits. It can be reused as often as you like. According to a particularly preferred development of the invention, the fill level measuring arrangement is connected to a monitoring device which preferably has a plurality of safety circuits and is designed in the form of a so-called liquid control interface, LCI, and which preferably communicates with analysis or control software, for example chromatography software. The monitoring device forms the central power supply unit for an analysis system, for example a preparative HPLC system, and switches it off, preferably with a time delay, in the presence of an alarm signal from one of the safety circuits. The area of application of the safety device according to the invention is also significantly expanded by the monitoring device. Ultimately, several safety circuits can be monitored. Communication, preferably in the form of a relay signal from the monitoring device with the analysis or control software, makes it possible to complete a process that is still being processed. Such a process takes about 15 minutes in a chromatography process, for example. The software is therefore able to initiate the end of the process properly. Thus, an orderly shutdown can take place by first ending the process and then turning off the power supply. The monitoring device can also be designed in such a way that the power supply is switched off after a time delay of approximately 20 minutes, so that the system, even if the software is not working properly, is switched off automatically after the latter time. Preferably, an additional timer function can be switched on manually on the monitoring device, which requests a signal in the form of a pulse from the analysis or control software at regular intervals. If this impulse does not arrive regularly or does not occur, the monitoring device can switch off the system, for example, within 4 minutes.

Advantageously, liquid-promoting components, such as pumps, can be supplied with electrical energy via the central power supply unit. This ensures that the liquid-conveying components are switched off, for example, when the level measuring arrangement detects leaked liquid. The monitoring device can be designed such that the liquid-conveying components are switched off immediately when liquid leaks are detected. If the level measurement arrangement detects that the liquid container is full, a time-delayed shutdown can also be used, as mentioned before, in such a way that an ongoing process can still be completed.

According to another development of the invention, the monitoring device is designed such that the maximum and / or the minimum liquid level in a liquid container, for example a storage liquid container, can be detected. It is also possible to connect the monitoring device not only to waste containers, but also to storage containers for liquid substances. In the latter case, an alarm signal is triggered at a minimal liquid level, which also enables the shutdown process to be started again. At the same time, a signal can also be output to the software in this case, which allows a running process to be ended. The monitoring device can also be designed such that a plurality of connections are provided for storage containers. As a result, the area of application of the safety device according to the invention is further enlarged. The monitoring device can thus be able to monitor the liquid level of a waste container, leaked solvent, the liquid level of several storage containers and the system state of the control software, trigger an alarm signal and switch off the power supply with a time delay as soon as one of the safety circuits indicates an alarm state. Monitoring the system status of the control software can include the question of whether the chromatography data system still has control over the HPLC system, in particular over the pumps of the system. The safety device according to the invention can thus also operate fully automatically and, for example, enable work to be carried out overnight. Even if the software is not working correctly, the monitoring device can initiate the shutdown of the entire system. In the latter case, the monitoring device advantageously has further measuring sensors and preferably a timer relay, which generates a signal in the event of an alarm after a preset time delay and thus opens a power current relay, which thus interrupts the power supply at a network output in the form of an output socket. Furthermore, a second timer relay, which can preferably be switched on or off, can be provided, which requests a signal in the form of a pulse, for example from a control software, at presettable time intervals and, if the pulse signal is absent, generates a signal itself and thereby opens a power current relay, which thus opens the Interrupts power supply at a network outlet in the form of preferably an outlet box.

Exemplary embodiments of the subject matter of the invention are explained in more detail below with reference to the drawing, with all of the features described and / or depicted individually or in any combination forming the subject matter of the present invention, independently of their summary and claims or their relationship. Show it:

Figure 1 is a schematic side view of a safety device for laboratory use.

2 shows a schematic, perspective view of a fill-level measuring arrangement of the safety device;

3 shows a schematic, partial section through the level measuring arrangement; and

Fig. 4 is a schematic circuit diagram of a monitoring device of the safety device.

1 shows a side view of a safety device 1 for laboratory operation, in particular for liquid chromatography systems. 1 is located on a laboratory trolley 2, which has a first, upper laboratory work surface 3, an underlying, second, lower laboratory work surface 4 and a deep sub-floor 5. The latter is arranged below the upper edges of wheels 6 of the laboratory trolley 2. The safety device 1 has a fill level measuring arrangement 7, which is connected to a liquid container 8 and generates an alarm signal when a specific liquid level in the liquid container 8 is detected.

According to the invention, the fill level measuring arrangement 7 is also connected to at least one of the laboratory work surfaces 3, 4 and is designed in such a way that the alarm signal is also generated when it detects leaked liquid on the at least one laboratory work surface 3, 4. For this purpose, the fill level measuring arrangement 7 is connected via drain lines 9 to a drain 10 provided in the laboratory work surface or surfaces.

In the exemplary embodiment shown in FIG. 1, the fill level measuring arrangement 7 is connected to both laboratory work surfaces 3, 4 via the drain lines 9 mentioned. Both drain lines 9 open into a common line 11, which is inclined towards the liquid container 8, so that there is a gradient from the drain lines 9 to the container.

The liquid container 8 can, for example, be a waste container 12 for liquid products, in particular for solvents.

As shown in more detail in FIGS. 2 and 3, the fill level measuring arrangement 7, namely a barrel adapter 24 of the same, has an inner space 13. Liquid flows into this inner space 13 from a certain fill level in the liquid container 8 through a through hole 18 described in more detail below. Furthermore, on the at least one laboratory work surface 3, 4, liquid flowing out flows into this interior space through an additional bore 23 described below, as will be explained in more detail below. The interior 13 is a sensor in the form of a level switch 14, preferably a so-called Vibration switch, assigned, the vibration forks 15 protrude into the interior.

According to an embodiment which is only indicated schematically in FIG. 1, the fill level measuring arrangement 7 projects with the fill level limit switch into the liquid container 8 from above. The fill level measuring arrangement 7, namely a barrel adapter 24, has in a side wall 16 of its interior 13 a through hole 18 connecting the interior 17 of the liquid container 8 with the interior 13 of the barrel adapter 24. As indicated in FIGS. 2 and 3, the through hole 18 is arranged in the side wall 16 above the lower end of the vibrating forks 15.

The barrel adapter 24 of the fill level measuring arrangement 7 has a cup-like element 19 which has the interior 13 and is screwed to the main part 21 of the barrel adapter 24 via its upper side 20. This screw connection can take place between the upper side 20 of the cup-like element 19 and the lower end of a longitudinal bore 22 of the main part 21. In the latter case, the outer diameter of the upper side 20 of the cup-like element 19 corresponds approximately to the inner diameter of the longitudinal bore 22.

Through two additional bores 28, however, liquid which arises during the chromatography process can also be conducted directly into the liquid container, for example a waste barrel.

The main part 21 of the barrel adapter 24 has an additional bore 23 opening into the longitudinal bore 22, through which liquid running out on one of the laboratory work surfaces 3, 4 can flow into the interior 13 of the barrel adapter 24. However, it is also possible for the liquid not to flow into the interior 13 not through the main part 21 of the barrel adapter 24, but rather via the through hole 18 designed as an overflow. According to the embodiment of the invention shown in FIG. 3, the additional bore 23 is L-shaped and only that in FIG. 3 Dotted line 11 or generally connected to the respective work surface 3, 4 via a drain line 9.

According to a preferred embodiment of the invention, the fill level measuring arrangement 7 has the so-called barrel adapter 24 and the fill level limit switch 14. As indicated in FIG. 3, the barrel adapter 24 is provided and designed below a flange 25. As indicated in FIG. 2, the barrel adapter 24 preferably has a G2 inch standard thread 27 in its upper region 26, which can be screwed into a corresponding counter thread of the liquid container 8 (not shown). For the sake of clarity, the thread 27 is omitted in FIG. 3. It is clear that the barrel adapter can also carry other thread types.

As shown in FIGS. 2 and 3, the level limit switch 14 extends on the one hand within the longitudinal bore 22 through the main part 2 1 d of the barrel adapter 24, with the vibration forks 15, which are located at the lower end of the level limit switch 14, in protrude the interior of the cavity formed as a siphon; on the other hand, the housing of the level limit switch also extends partially above the flange 25. The level limit switch 14 is preferably detachably connected to the main part 21.

According to the embodiment of the invention shown in FIG. 2, in addition to the additional bore 23, two further bores 28 are provided in the main part 21 of the barrel adapter 24. These bores provide direct access to the interior 17 of the liquid container 8. The further bores 28 thus constitute a so-called direct inlet. The connections can be made via stainless steel angle pipes with a hose olive, onto which drain hoses are placed. An angle tube 29 is only shown in dash-dotted lines in FIG. 3 and is usually pushed into the bore 28 as far as it will go. The angle tubes 29 can have different lengths, so that they cannot be confused with one another. Another of the direct inlets 28 can serve, for example, as an inlet for steel capillaries (not shown) of an HPLC system. In contrast, the Additional bore 23 connects to the cup-like element 19, called a siphon. Liquid that reaches the liquid container 8, for example the waste container 12, via this inlet is thus guided via the siphon-like element 19.

According to a preferred embodiment, the fill level measuring arrangement 7 is preferably provided with a plurality of safety circuits

Monitoring device 31, also called liquid control interface or LCI for short, connected via a signal cable 32 (see FIGS. 1, 4).

The monitoring device contains several electrical switching elements, which are explained in more detail below.

4, in which a schematic circuit diagram of the monitoring device 31 is shown, the monitoring device 31 has a power relay 40, preferably a semiconductor relay, as the central power supply unit. The power relay 40 is connected between the mains input 42 and the mains output 43, hereinafter also referred to as an outlet socket. In the event of an alarm of the fill level limit switch 14 of the fill level measuring device, the signal is led via the signal cable 32 to the monitoring device 31 and converted into a relay signal by a transmitter 33. This relay signal is then passed to a timer relay 39. At the same time, the signal is forwarded to the control software by means of a signal transmission 35, for example in a personal computer 34, also called a PC. After a time delay that can be preset at the timer relay 39, the signal is passed to the power relay 40, which thus interrupts the power supply at the mains outlet 43 in the form of the outlet box.

As shown in the embodiment of the invention shown in FIG. 4, further measuring sensors 41 in the form of level meters (four such elements are shown schematically in FIG. 4) can be connected to the monitoring device 31, the connections of which within the monitoring device 31 are linked together in a parallel circuit. In the event of an alarm, this generates a signal via a relay 44, which is sent to the timer relay 39. The latter conducts the delayed switch-off of the power relay 40 in. At the same time, a signal is forwarded to the control software in the PC 34 by means of a signal transmission 45.

According to the embodiment of the invention shown in FIG. 4, the monitoring device 31 has an additional monitoring function in the form of a second timer relay 38 that can be switched on and off manually on the operator panel of the device via a switch 37. This must receive an external signal, such as an impulse, for example, from the control software of a liquid chromatography system via a pulse transmission 36 e at presettable time intervals. Otherwise, it sends a signal to the power relay 40, which then interrupts the power supply at the network outlet 43, for example the aforementioned outlet, without delay.

4, the relays 33, 38, 39 and 44 and the sensor 41 are shown schematically as closing relays. It is clear that the circuit diagram with the same elements can also be constructed with opening relays. Furthermore, the entirety of the switching elements shown schematically in Fig. 4 as a processor, i.e. be formed as an integrated circuit.

The monitoring device 31 preferably communicates with analysis and / or control software, for example chromatography software, and at the same time forms the central power supply unit for an analysis system, such as a preparative HPLC system. The monitoring device 31 switches off the analysis system in the presence of an alarm signal from one of the security circuits, as mentioned above, preferably with a time delay. Via the monitoring device 31, primarily liquid-conveying components (not shown), preferably pumps, can be supplied with electrical energy, so that they can be safely switched off when an alarm signal is present. The monitoring device 31 is designed such that the maximum and / or the minimum liquid level can also be detected in a liquid container 8, for example in a storage liquid container. In this respect, the monitoring device can be connected both to the liquid container 8 designed as waste container 12 and to further liquid containers (not shown) which are designed as liquid storage containers.

The monitoring device 31 is thus designed as an intelligent solvent monitoring system with a plurality of safety circuits, which operate independently of the chromatography data system. The monitoring device can communicate with a chromatography software by means of relay signals, so that this in turn can be triggered early for the corresponding actions. As mentioned above, the monitoring device preferably forms the central power supply unit for the system, for example a preparative H PLC system. The solvent supply components, namely the pumps, are primarily supplied with electrical energy via the power supply unit. The monitoring device is able to interrupt the entire power supply of the system in the event of an alarm in order to prevent any uncontrolled solvent leakage, due to a full liquid container, in particular a waste container, or for example due to a liquid escaping on a laboratory work surface or, for example, due to a software crash during an unsupervised operation, such as overnight.

The monitoring device can monitor four system states during operation, for example. As previously indicated, this can be the fill level of a waste container; on the other hand, leaking solvent can be detected early on a laboratory work surface, and the fill level of, for example, up to four storage liquid containers can be monitored; In addition, the system status of the control software can be monitored so that it can be checked whether the chromatography data system still has control over the HPLC system, ie primarily over the pumps. As soon as the fill level sensor of the fill level measuring arrangement on the waste container responds, a remaining volume usually remains free, so that a time-delayed shutdown, which allows the execution of a currently running laboratory process, such as a chromatography process, is initiated. At the same time, a signal in the form of a relay contact can be sent as input to the control software, which can end the ongoing process but can no longer process further samples. After the time delay has expired, the power supply is then cut off in any case.

If a liquid, such as solvent, escapes at one point on a laboratory work surface 3, 4, this is conducted in the shortest way via the drain line 9 and / or the line 11 to the fill level measuring arrangement into the interior 13 of the siphon-like element 19 of the barrel adapter , As soon as a few milliliters have reached the level sensor, it responds and triggers the same shutdown procedure as with a full waste container. It is also possible to switch off the operation of the system immediately in the latter case. As soon as the fill level in the interior 13 of the cup-like element 19 of the barrel adapter 24 of the fill level measuring arrangement 7 has reached a certain level, the frequency of the vibrating forks 15 of the fill level limit switch 14 will change, which causes the generation of an alarm signal.

A sufficient liquid level in storage liquid containers can be monitored, for example, with so-called empty level probes. If the storage container is empty, the monitoring device can transmit a signal as input to the control software so that it can complete the ongoing process, but cannot process another sample. The empty level probes can already respond if there is still a small reserve stock in the storage container. In another case, the monitoring device can transmit a signal, as mentioned above, and then additionally bring about the time-delayed shutdown of the entire system. In addition, the monitoring device can serve to receive a signal from the control software in short time intervals, such as every 4 minutes, and otherwise to switch off the power supply immediately. This procedure can be useful for preparative HPLC systems that should work unattended for long periods. This function ensures that the chromatography data system actually still has control over the system in operation.

The handling of the safety device according to the invention is explained in more detail below.

First, the fill level measuring arrangement 7 is screwed with its barrel adapter 24 onto the liquid container 8, for example the waste container 12, with its external thread 27. Then the lines 9 and / or 11 or the angle tubes 29 and further lines are introduced. Finally, the fill level limit switch 14 is inserted into the inner bore 22 of the main part 21 to such an extent that the vibrating forks 15 are located below the through bore 18. Furthermore, the fill level limit switch 14 is connected to the monitoring device 31 by means of the signal line 32.

As soon as liquid reaches the interior 13 of the cup-like element 19 through the through hole 18 or via the additional hole 23 so that the vibrating forks 15 are immersed in liquid, the frequency of the vibrating forks 15 changes. This triggers an alarm signal. In this respect, according to the invention, an alarm signal is always triggered when there is liquid in the interior, regardless of whether this liquid passes through the through-hole 1 8 from the interior space 1 7 of the liquid container 8 into the interior 13 of the element 19 or via the additional bore 23 has entered the interior 13 of the element 19.

The fill level limit switch 14 is preferably a single part and can be lifted as a whole from the main part 2 1 and the cup-like element 19 become. As previously mentioned, the barrel adapter 24 is preferably made of metal (such as stainless steel or aluminum) or an inert plastic. The through hole 18 serves not only for the entry of liquid from the interior 17 of the liquid container 8 into the interior 13 of the level measuring arrangement 7, but also for the exit of solvent, which reaches the interior 13 of the level measuring arrangement 7 via the additional hole 23.

When dismantling, the level switch 14 and the lines including the angle tubes are first lifted out of the barrel adapter and removed. Then the barrel adapter is unscrewed from the liquid container and lifted out. Finally, the cup-like element 19 is detached from the main part 21 of the fill level measuring arrangement 7, preferably unscrewed.

This creates a safety device for laboratory use that is versatile in use.

Claims

claims

1. Safety device for laboratory operation, in particular for liquid chromatography systems, with a fill level measuring arrangement (7) which is connected to a liquid container (8) and generates an alarm signal when a specific liquid level in the liquid container (8) is detected, characterized in that the fill level measuring arrangement ( 7) is also connected to at least one laboratory work surface (3, 4) and also generates the alarm signal when it detects leaked liquid on the at least one laboratory work surface (3, 4).

2. Safety device according to claim 1, characterized in that the

Filling level measuring arrangement (7) has an interior (13) into which liquid flows from a certain liquid level in the liquid container (8) and / or on the at least one laboratory work surface (3, 4) and to which a fill level limit switch (14), preferably a vibration limit switch is assigned.

3. Safety device according to claim 2, characterized in that the

Level measuring arrangement (7) protrudes from above into the liquid container (8) and preferably in a side wall (16) of its interior (13) a connecting the interior (17) of the liquid container (8) with the interior (13) of the level measuring arrangement (7) Has through hole (18).

4. Safety device according to claim 2 or 3, characterized in that the fill level measuring arrangement (7) has a cup-like element (19) which has the interior (13) and which preferably has its upper side (20) with the lower end of a longitudinal bore (22). the main part (21) of the level measuring arrangement (7) is screwed.

5. Safety device according to claim 4, characterized in that the

Main part (21) of the level measuring arrangement (7) has an additional hole (23) opening into the longitudinal bore (22), through which liquid running out on the at least one laboratory work surface (3, 4) into the interior (13) of the level measuring arrangement (7) flows.

6. Safety device according to one of the preceding claims, characterized in that the level measuring arrangement (7) is additionally a barrel adapter (24).

7. Safety device according to one of the preceding claims, characterized in that the fill level measuring arrangement (7) is connected to a monitoring device (31), which preferably has a plurality of safety circuits and is designed in the form of a liquid control interface, LCI, which is preferably connected to an analysis and / or control software, for example chromatography software, communicates, forms the central power supply unit for an analysis system, for example a preparative HPLC system, and switches off the analysis system if there is an alarm signal from one of the safety circuits, preferably with a time delay.

8. Safety device according to claim 7, characterized in that liquid-conveying components, preferably pumps, can be supplied with electrical energy via the central power supply unit.

9. Safety device according to claim 7 or 8, characterized in that the monitoring device (31) is designed such that the maximum and / or the minimum liquid level in a liquid container (8) can be detected.

10. Safety device according to claim 9, characterized in that on the monitoring device (31) further measuring sensors (41) preferably in Form of level meters for triggering an alarm when a maximum and / or minimum liquid level in a liquid container (8) are connected.

11. Safety device according to one of claims 7 to 10, characterized in that the monitoring device (31) has a timer relay (39) which generates a signal in the event of an alarm after a presettable time delay and thus opens a power relay (40) which thus opens the Interrupts power supply at a network outlet (43), preferably in the form of an outlet box.

12. Safety device according to one of claims 7 to 11, characterized in that the monitoring device (31) contains a second timer relay (38) which requests a signal in the form of a pulse, for example from a control software, at presettable time intervals and even if the pulse signal fails to appear Generates a signal and thereby opens a power relay (40), which thus interrupts the power supply at a network outlet (43), preferably in the form of an outlet box.

13. Safety device according to claim 12, characterized in that the

Function of the second timer relay (38) can be switched on or off.