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EP-4361575-B1 - METHOD FOR MONITORING LIQUID CONTENT

EP4361575B1EP 4361575 B1EP4361575 B1EP 4361575B1EP-4361575-B1

Inventors

  • FRÖJDH, Håkan
  • FORSLUND, DAVID
  • JOHANSSON, Elias

Dates

Publication Date
20260513
Application Date
20221028

Claims (20)

  1. A method for monitoring liquid content in a container (13; 13') used in a bench top fluid handling system (101), whereby liquid is pumped to and/or from said container (13; 13') during a process run in the bench top fluid handling system, said method comprising the steps of: - detecting a position of a liquid surface in the container (13; 13') by use of a mmWave radar sensor (21) provided in a sensor arrangement (1; 1') attached to the container (13; 13'); - determining amount of liquid in said container (13; 13') based on said detected position of the liquid surface and on prestored geometry information of said container (13; 13'); and - presenting information to a user about said determined amount of liquid.
  2. Method according to claim 1, wherein the step of detecting a position of a liquid surface in the container further comprises subtracting a reference signal from a radar signal received from the mmWave radar sensor, said reference signal being measured with the sensor arrangement (1; 1') comprising said mmWave radar sensor (21) positioned in a free measuring environment, wherein said free measuring environment does not comprise any objects, within a measuring range of the mmWave radar sensor, giving an echo to a radar signal sent from the mmWave radar sensor.
  3. Method according to claim 1 or 2, wherein the bench top fluid handling system is a chromatography system.
  4. Method according to any one of the preceding claims, further comprising the step of: - detecting if the mmWave radar sensor (21) is positioned in an operating position in which it is possible to detect a position of a liquid surface in the container (13; 13'), wherein the step of determining amount of liquid in said container comprises a primary determination step in which the determination is based on said detected position of the liquid surface and on prestored geometry information of said container (13; 13'), which primary determination step is performed when the mmWave radar sensor (21) is detected to be provided in the operating position.
  5. Method according to claim 4, wherein said step of detecting if the mmWave radar sensor (21) is positioned in an operating position comprises measuring a tilt angle of a sensor housing (24) comprising said mmWave radar sensor (21), said tilt angle being measured by an angle sensor (25') provided in the sensor housing (24), whereby the sensor housing can be moved into at least an open and a closed position in relation to the container (13; 13') which two positions can be differentiated by measuring the tilt angle of the sensor housing (24) and whereby the mmWave radar sensor is only provided in the operating position when the sensor housing (24) is in the closed position.
  6. Method according to claim 5, wherein the step of detecting if the mmWave radar sensor (21) is positioned in an operating position comprises measuring the tilt angel of the sensor housing (24) along at least two axes and evaluating by comparing tilting along these at least two axes if a measured tilt angle is caused by a changed position of the sensor housing (24) between the open and closed position or by a tilting of the whole container.
  7. Method according to any one of the claims 4-6, wherein the step of determining amount of liquid in said container further comprises a secondary determination step performed when the mmWave radar sensor (21) is not detected to be provided in the operating position, wherein said secondary determination is based on information about pumped liquid volume from one or more pumps (113) provided in the bench top fluid handling system (101) for pumping liquid to and/or from the container (13; 13').
  8. Method according to any one of the preceding claims, wherein the step of determining amount of liquid in said container (13; 13') further is based on information about pumped liquid volume from one or more pumps (113) provided in the bench top fluid handling system (101) for pumping liquid to and/or from the container (13; 13') for detected positions of the liquid surface being closer to a bottom of the container than a predefined threshold.
  9. Method according to any one of the preceding claims, further comprising the step of automatically stop pumping liquid to or from the container (13; 13') when a determined amount of liquid is above and/or below a predetermined threshold.
  10. Method according to any one of the preceding claims, further comprising the steps of: - positioning a sensor housing (24) comprising said mmWaveradar sensor (21) in a closed position covering at least a part of a top opening (11; 11') of the container (13; 13') before the step of detecting a position of a liquid surface in the container, whereby the mmWave radar sensor (21) is provided in the operating position for detecting the position of the liquid surface when the sensor housing is positioned in the closed position; and - positioning said sensor housing (24) in an open position in which the sensor housing (24) is not covering the top opening (11; 11') of the container (13; 13') when new liquid is to be filled into the container, whereby the mmWave radar sensor (21) is not provided in the operating position when the sensor housing is in open position.
  11. Method according to any one of the preceding claims, further comprising an initial step of determining the relation between liquid surface position and amount of liquid in the container (13; 13') for each new type of container such that container geometry information for each type of used container (13; 13') can be used in the step of determining amount of liquid in said container.
  12. Method according to any one of the preceding claims, wherein this is a method for monitoring liquid content in a container (13; 13') having a height between 10-100 cm and/or a volume between 0,5-20 liter used in a bench top fluid handling system.
  13. Method according to any one of the preceding claims, wherein said step of detecting a position of a liquid surface comprises measuring a distance between the mmWave radar sensor (21) and the liquid surface in the container (13; 13') by use of the radar sensor (21) which is positioned above the liquid surface in connection with the container (13; 13').
  14. A bench top fluid handling system (101) comprising: - a control system (111); - at least one container (13; 13') configured to comprise liquid to be pumped to and/or from at least one other component (103) in the bench top fluid handling system (101); - at least one sensor arrangement (1; 1') configured to be connected to one of the at least one container (13; 13') and to the control system (111), said sensor arrangement (1; 1') comprising a mmWave radar sensor (21) which can be positioned in an operating position in relation to the container in which operating position it can detect a position of a liquid surface in the container (13; 13'); - a pump (113) and fluid connections (114) configured for pumping liquid between said at least one container (13; 13') and said at least one other component (103), said pump (113) being connected to the control system (111), wherein said control system (111) is configured for determining amount of liquid in said container (13; 13') based on said detected position of the liquid surface and on prestored geometry information of said container (13; 13') and wherein said control system is configured for presenting to a user information about said determined amount of liquid.
  15. Bench top fluid handling system (101) according to claim 14, wherein said control system is configured to perform the method according to any one of the claims 1-13.
  16. Bench top fluid handling system (101) according to any one of the claims 14-15, wherein said bench top fluid handling system is a chromatography system and wherein said at least one other component (103) comprise at least one chromatography column (103).
  17. Bench top fluid handling system (101) according to any one of the claims 14-16, wherein the sensor arrangement (1; 1') is configured such that it can be positioned in at least a closed and an open position, wherein in the closed position a sensor housing (24) of said sensor arrangement comprising said mmWave radar sensor (21) is at least partly covering a top opening (11; 11') of the container (13; 13') and in the open position said sensor housing (24) is not covering the top opening (11; 11') of the container (13; 13').
  18. Bench top fluid handling system (101) according to any one of the claims 14-17, wherein the sensor arrangement (1; 1') comprises an angle sensor (25').
  19. Bench top fluid handling system (101) according to any one of the claims 14-18, wherein the container has a height between 10-100 cm and/or a volume between 0,5-20 liter.
  20. A computer program product comprising instructions which, when executed in a processor in a control system (111) provided in a bench top fluid handling system (101), cause the control system (111) to perform the method according to any one of the claims 1-13.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for monitoring liquid content in a container used in a bench top fluid handling system and to a bench top fluid handling system comprising a sensor arrangement for monitoring liquid content in a container used in the bench top fluid handling system. BACKGROUND In bench top fluid handling systems, such as for example fluid analyzing systems, separation systems and chromatography systems, it is important to keep track of content in bottles and other containers for different liquids such as solvent and waste handled in the system. If a container run empty the process is disturbed and if a container is overfilled liquid may be wasted and there may be problems with contamination. Overflow of a liquid may also be a safety problem with risk of personal injury. There are different commonly used methods for monitoring liquid levels in containers in these types of systems. One possibility is to use dead reckoning, i.e. information from the pumps in the system about how much liquid is pumped to and from the containers. However, with such a system it is important that the user always correctly updates content in the container when they are refilled or emptied. Another method for monitoring liquid levels in chromatography systems is disclosed in US7419598 where a bubbler is positioned within a solvent reservoir with its opening near the bottom of the system to measure the pressure of solvent and hereby monitor the level of the solvent. This measuring method is however dependent on density of the liquid and it will often not provide good enough measuring precision to predict if the amount of solvent is enough for the method run or if the remaining empty volume in a waste container is enough for a method run. In US2003/0175157 a method for fluid content control in a container is disclosed where a weight scale is used for detecting the weight of the fluid in a container. Also in this method a density of the fluid needs to be known or estimated whereby the measuring precision may not be exact, especially for mixed fluids such as in waste containers. Furthermore, weight of the container, weight of tubing provided to the container and any possible other parts of the system coming into contact with the container will affect the measured weight of the container and hereby affect measuring precision. Hereby also the containers need to be positioned free, without contacting anything which may be problematic. US 2012/031510 A1 discloses a method for monitoring liquid content in a tank in an installation for treatment by chromatography, liquid is pumped to a container filled with liquid and located in the tank, volume of liquid is determined and informed. SUMMARY An object of the present invention is to provide an improved method for monitoring liquid level in containers in bench top fluid handling systems. A further object of the invention is to provide a reliable and easily handled method and system for monitoring liquid levels in bench top fluid handling systems. This is achieved by a method, a bench top fluid handling system and a computer program product according to the independent claims. According to one aspect of the invention a method for monitoring liquid content in a container used in a bench top fluid handling system is provided, whereby liquid is pumped to and/or from said container during a process run in the bench top fluid handling system, said method comprising the steps of: detecting a position of a liquid surface in the container by use of a mmWave radar sensor provided in a sensor arrangement attached to the container;determining amount of liquid in said container based on said detected position of the liquid surface and on prestored geometry information of said container; andpresenting information to a user about said determined amount of liquid. According to another aspect of the invention a bench top fluid handling system is provided comprising: a control system;at least one container configured to comprise liquid to be pumped to and/or from at least one other component in the bench top fluid handling system;at least one sensor arrangement configured to be connected to one of the at least one container and to the control system, said sensor arrangement comprising a mmWave radar sensor which can be positioned in an operating position in relation to the container in which operating position it can detect a position of a liquid surface in the container;a pump and fluid connections configured for pumping liquid between said at least one container and said at least one other component, said pump being connected to the control system, wherein said control system is configured for determining amount of liquid in said container based on said detected position of the liquid surface and on prestored geometry information of said container and wherein said control system is configured for presenting to a user information about said determined amo