EP1779082A2 - Methode et dispositif pour detecter une fuite dans un conditionnement - Google Patents

Methode et dispositif pour detecter une fuite dans un conditionnement

Info

Publication number
EP1779082A2
EP1779082A2 EP05767937A EP05767937A EP1779082A2 EP 1779082 A2 EP1779082 A2 EP 1779082A2 EP 05767937 A EP05767937 A EP 05767937A EP 05767937 A EP05767937 A EP 05767937A EP 1779082 A2 EP1779082 A2 EP 1779082A2
Authority
EP
European Patent Office
Prior art keywords
package
gas
detecting device
concentration
measuring
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05767937A
Other languages
German (de)
English (en)
Inventor
Karel Auguste Loth
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Lothgenoten BV
Original Assignee
Lothgenoten BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Lothgenoten BV filed Critical Lothgenoten BV
Publication of EP1779082A2 publication Critical patent/EP1779082A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/26—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors
    • G01M3/32—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators
    • G01M3/3281—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators removably mounted in a test cell

Definitions

  • the invention relates to a method ' for detecting a leak in a packaging.
  • Products are often packaged in a package sealed in gas-tight manner, wherein a part of the content of this package consists of a gas mixture which has a composition other than the ambient air.
  • a gas or gas mixture is added to the air in the package so as to influence the conditions of the product, particularly to improve the storage life hereof. If the package is not gas-tight, or not wholly so, the package then has a leak, and there is therefore a risk of the protective gas or gas mixture escaping or being displaced by ambient air.
  • the storage life of the packaged products is hereby adversely affected.
  • the present invention provides a method for detecting a leak in a package at least partly filled with a gas, comprising the steps of exposing a package to a reduced pressure, measuring the concentration of the gas in the vicinity of the package, comparing the measured concentration to a limit value and emitting a signal when the measured value exceeds the limit value.
  • the concentration measurement preferably does not take place simultaneously with the exposure to the reduced pressure. By as it were uncoupling the concentration measurement from the pressure decrease, the packaging process and the concentration measurement can be individually optimized.
  • the concentration measurement takes place over a longer period of time than the exposure to the reduced pressure, the time for which the package is exposed to the pressure decrease can be kept very short so that the packaging process is not hereby delayed, or hardly so, while sufficient time can still be taken for an accurate measurement of the gas concentration.
  • it is preferably stored separated from the vicinity of the package prior to the concentration measurement.
  • a plurality of samples can be taken successively, the gas concentration of each sample can be measured and the measured values can be compared to each other. It is also possible to envisage the concentration measurement taking place in different steps, wherein the manner in which a subsequent measurement is performed depends on the result of a previous measurement. The order of magnitude of a leak can thus be determined in a first measurement, whereafter a second, more precise measurement can be adjusted hereto.
  • the present invention also provides a device for carrying out the above described method.
  • a leak detecting device comprises means for exposing the package to a reduced pressure, means for measuring the concentration of the gas in the vicinity of the package, means connected to the measuring means for comparing the measured gas concentration to a limit value, and means connected to the comparing means for emitting a signal when the measured value exceeds the limit value.
  • the measuring means can have a longer cycle time than the pressure reducing means. It is hereby possible to still perform an accurate measurement of concentration in a packaging line where packages are passing at high speed, while making use of relatively simple measuring means.
  • the measuring means can here for instance comprise an NDIR gas detector, an effective detector type which is commercially available at relatively low cost.
  • the NDIR gas detector preferably comprises a measuring cell having means for optimizing the flow therein.
  • the measuring means comprise a buffer connected to the pressure reducing means via a sample line, as well as valves placed in the sample line between the buffer and the pressure reducing means on the one hand and between the buffer and the measuring means on the other, samples of the gas from the vicinity of the package can be stored interim before being analysed.
  • the buffer is connected to the environment or to a space in which a determined pressure prevails, so that the sample stored in the buffer can be supplied to the measuring means at ambient pressure or under the determined pressure. This is particularly important when the measuring means are of a type adapted to process a constant gas flow.
  • the measuring means are preferably connected releasably to the pressure reducing means, whereby they can be exchanged when for instance packages with a different gas or a different concentration of the gas therein must be tested for leaks. If the measuring means are then connected by plug connections and rapid-action couplings to the pressure reducing means, the exchange can take place rapidly and in simple manner.
  • the leak detecting device When the leak detecting device according to the invention is provided with a number of sets of measuring means connected in parallel and each connected to the pressure reducing means, packages which pass very quickly, and are thus exposed to an underpressure only very briefly, can still also be tested in reliable manner by performing different measurements simultaneously.
  • a preferred embodiment of the leak detecting device is provided with a number of sets of measuring means connected in series and having a diversity of measurement sensitivities .
  • a first set of measuring means can thus determine the order of magnitude of the leak, whereafter on the basis hereof a smaller sample than normal can for instance be added to the subsequent, more sensitive set of measuring means. It is thus possible to prevent these second measuring means being as it were "flooded" by the high gas concentration, whereby the measurement sensitivity could be temporarily reduced.
  • a structurally simple leak detecting device is obtained when the pressure reducing means comprise a housing at least partly enclosing the package and a vacuum pump connected thereto.
  • This housing is preferably placed above a conveyor supplying and discharging the package, has an open bottom and is movable substantially transversely of the conveyor.
  • the housing can thus be placed over a package for testing and removed therefrom quickly and easily.
  • this latter can advantageously be manufactured from a lightweight plastic material such as a plastic composite reinforced with glass fibre or carbon fibre.
  • the leak detecting device can further be provided with drive means connected to the housing for causing this latter to move transversely of the conveyor, which drive means are placed under the conveyor, whereby a relatively compact device is obtained.
  • the leak detecting device is preferably provided with a buffer placed between the housing and the vacuum pump, and with a valve placed between the buffer and the housing.
  • Fig. 1 shows a schematic side view of a first embodiment of the leak detecting device according to the invention, which is suitable for a so-called "direct" detection,
  • Fig. 2 is a view corresponding with fig. 1 of a second embodiment of the leak detecting device according to the invention, which is suitable for a so-called "indirect" detection
  • Fig. 3 shows a variant of the embodiment of fig. 2 with a plurality of sets of measuring means connected in parallel,
  • Fig. 4 in turn shows another variant of the indirect leak detecting device according to the invention with a pressureless buffer
  • FIG. 5 shows a variant of the indirect leak detecting device with two sets of measuring means in series.
  • a device 1 for detecting a leak in a package P at least partly filled with gas - in this example a gas mixture with an increased concentration of carbon dioxide relative to the ambient air - comprises means 2 for exposing package P to a reduced pressure (fig. 1) .
  • Leak detecting device 1 further comprises means 3 for measuring the concentration of the gas in the vicinity of package P, means connected to measuring means 3 for comparing the measured gas concentration to a limit value, and means connected to the comparing means for emitting a signal when the measured value exceeds the limit value.
  • the comparing means and the signal-emitting means are not shown individually here.
  • the pressure reducing means are not shown individually here.
  • housing 4 at least partly enclosing package P, and a vacuum pump 6 connected to the housing via a line 5 with a valve 9 herein.
  • Housing 4 is here placed above a conveyor 7 supplying and discharging the package (with conveying direction T) , and has an open bottom.
  • drive means (not shown here) housing 4 is movable transversely of conveyor 7 (as according to arrow M) between the shown measuring position, in which housing 4 defines a closed space together with conveyor 7, and a position allowing passage, in which housing 4 hangs above conveyor 7 at a height such that a tested package P can be discharged and a subsequent package P' can be supplied.
  • a further seal 8 is arranged around the open bottom of housing 4.
  • Measuring means 3 here comprise a gas detector 10, for instance of the NDIR type, which is based on the Non- Dispersive Infra Red absorption principle.
  • This gas detector 10 comprises a measuring cell 11 with a source 12 of IR light on one side and a sensor 13 on the opposite side.
  • the IR source 12 is further provided with a filter which allows through as much radiation as possible with a wavelength for which the gas for detecting has a relatively great absorption value.
  • Sensor 13 must of course also be sensitive to radiation of precisely this wavelength. The higher the concentration of the gas in measuring cell 11 becomes, the more IR radiation will thus be absorbed and less will reach sensor 13. The ratio between the intensity of the absorbed radiation and the emitted radiation is thus a measure for the concentration.
  • Gas detector 10 is otherwise connected to the above mentioned comparing means and signal generating means via lines 16 (shown schematically here) .
  • Measuring means 3 further comprise a second vacuum pump 14 with which a gas sample can be pumped from housing 4 via a line 15 to gas detector 10.
  • This sample pump 14 can create a lower pump pressure than vacuum pump 6 of pressure reducing means 2, and is in operation as long as housing 4 lies on conveyor 7.
  • the operation of this embodiment of leak detecting device 1 is as follows. When a package P for testing is supplied by conveyor 7, housing 4 is moved downward by the drive means and placed over this package P, whereby a closed and airtight space is created around package P. Just as the ambient air, the air in this closed space has a determined concentration of the gas with the same composition as the gas mixture present in the package. When valve 9 is opened, vacuum pump 6 reduces the pressure in the space until it is lower than the pressure in package P.
  • the sample pump 14 draws air out of the space enclosed by housing 4 and pumps it through measuring cell 11 of the NDIR gas detector 10.
  • the concentration of the gas or gas mixture to which the detector 10 is sensitive is determined on the basis of the detected absorption of IR radiation, thus the difference between the radiation emitted by source 12 and the radiation absorbed by sensor 13. This detection is transmitted to the comparing and signal-emitting means via lines 16.
  • a leak in package P is hereby demonstrated.
  • a detected leak can be indicated and/or, transmitted in the form of a signal or action whereby a process or system can be controlled.
  • On the basis of this detection package P can for instance be taken out of the packaging line at a subsequent station.
  • An alternative embodiment of the leak detecting device 101 according to the invention is provided with a buffer 117 in line 115 between sample pump 114 and gas detector 110 (fig. 2) .
  • Controllable valves 118, 119 are accommodated in line 115 on either side of this buffer 117.
  • a branch line 120 with valve 121 is further connected to line 115 between sample pump 114 and the first valve 118.
  • Provisions 122 for instance in the form of a spring-loaded piston or bellows, are otherwise arranged in buffer 117 to enable variation of the volume thereof.
  • the concentration measurement can be separated in time from the exposure of package P to an underpressure.
  • the package therefore only has to remain stored in housing 4 for a short time, whereafter gas samples stored in buffer 117 can be supplied to gas detector 110 at a suitable speed.
  • Housing 104 can be taken off package P and conveyor 107 can supply the subsequent package P' while the concentration measurement of the gas is still taking place or has yet to start, so-called "indirect" measurement.
  • a plurality of samples can be taken successively and supplied to gas detector 110. Change in the measured gas concentration over a plurality of measurements is an indication of a leaking package or packages (serial application) .
  • sample pump 114 draws a gas sample out of the space bound by housing 104 and pumps this gas sample into buffer 117, wherein the pressure in buffer 117 increases.
  • the gas sample is buffered. This latter can now be guided through measuring cell 111 of gas detector 110 by opening valve 119, whereafter the buffer is emptied by piston 122.
  • the gas sample displaces the gas present in gas detector 110 and remains there until the following gas sample is presented. While gas detector 110 analyses the gas, buffer 117 can be filled again at a random time with a subsequent gas sample.
  • flushing valve 121 can be opened in order to flush or aerate sample pump 114 and pump line 115.
  • the pressure reducing means 102 are otherwise also provided with a buffer 123 between vacuum pump 106 and valve 109.
  • a buffer 123 between vacuum pump 106 and valve 109.
  • measuring cell 111 of gas detector 110 is adapted in this embodiment to optimize the flow of the gas sample.
  • measuring cell 111 By adapting the form of measuring cell 111 such that it has the smallest possible volume and the smallest possible flow resistance to the gas mixture, measuring cell 111 can be filled in the shortest possible time with new gas mixture for measuring, whereby measurement can take place more rapidly. It is also important to select the form of measuring cell 111 such that the least possible mixing occurs in cell 111 and in all other components of device 101. This is realized here by embodying measuring cell 111 with rounded corners and the smallest possible "dead volume", which means volume which is not functional but does disrupt the flow pattern.
  • the sample line 215 is divided into two parallel branches 215A and 215B, each having a buffer 117A, ' 117B and associated valves 118A, 118B and 119A, 119B (fig. 3) .
  • both buffers 117A, 117B can be alternately filled or emptied in gas detector 210.
  • the capacity and therewith the flexibility of the leak detecting device 201 is hereby increased.
  • Each branch 215A, 215B of the sample line could otherwise also be connected to its own gas detector (not shown here) .
  • a measuring device By assembling a device from combinations of the above described apparatus a measuring device can be assembled which, depending on the given conditions, is most satisfactory in a determined situation.
  • a device By embodying a device with controlled parallel measuring systems which can be operated and activated independently of each other and which alternately measure one or more supplied package (s), it is possible to operate with a total measuring time which is longer than the cycle time of the leak tester (parallel measuring systems) .
  • a pressureless buffer 317 consists of a space with open outlet opening to the ambient air, in which the flow profile is such that during the sampling time there occurs no or little mixing with the ambient air, such as a hose or pipe with a small internal diameter, a labyrinth or space of other form in which no or hardly any mixing occurs under the stated conditions.
  • Sample valve 318 is opened for a length of time such that at least as much gas is stored in the buffer 317 with constant pressure as the gas detector 310 with its own suction pump 324 needs for a measurement. After closing of valve 318 the pressure in buffer 317 becomes the same as the ambient air and the gas sample in buffer 317 is supplied at ambient pressure to gas detector 310.
  • the device 401 is provided with a relatively insensitive gas detector 425, once again for instance an NDIR detector, which is connected between housing 404 and the actual gas detector 410.
  • This advance detector 425 detects very high concentrations resulting from large leaks, and controls sample valve 418 on the basis thereof such that only a small sample is supplied to detector 410. This prevents this detector 410 being "flooded", whereby the measurement accuracy would be temporarily reduced.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Examining Or Testing Airtightness (AREA)

Abstract

L'invention concerne une méthode pour détecter une fuite dans un conditionnement au moins partiellement rempli de gaz. La méthode de l'invention comprend les étapes consistant à: exposer un conditionnement à une pression réduite, mesurer la concentration du gaz à proximité du conditionnement, comparer la concentration mesurée à une valeur limite, et émettre un signal, lorsque la valeur mesurée dépasse la valeur limite. Il n'est pas nécessaire que la mesure de concentration ne s'effectue simultanément à l'exposition à la pression réduite, mais un échantillon peut par exemple être prélevé à proximité du conditionnement, la concentration de l'échantillon étant mesurée pendant une période prolongée. L'invention concerne un dispositif de détection de fuite pour mettre en oeuvre cette méthode. Le dispositif est doté d'un moyen pour exposer le conditionnement à une pression réduite, d'un moyen pour mesurer la concentration du gaz à proximité du conditionnement, d'un moyen relié au moyen de mesure pour comparer la concentration de gaz mesurée à la valeur limite, et d'un moyen relié au moyen de comparaison pour émettre un signal lorsque la valeur mesurée dépasse la valeur limite. Le moyen de mesure peut comprendre un détecteur de gaz NDIR.
EP05767937A 2004-07-20 2005-07-20 Methode et dispositif pour detecter une fuite dans un conditionnement Withdrawn EP1779082A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL1026692 2004-07-20
PCT/NL2005/000527 WO2006009442A2 (fr) 2004-07-20 2005-07-20 Methode et dispositif pour detecter une fuite dans un conditionnement

Publications (1)

Publication Number Publication Date
EP1779082A2 true EP1779082A2 (fr) 2007-05-02

Family

ID=34982134

Family Applications (1)

Application Number Title Priority Date Filing Date
EP05767937A Withdrawn EP1779082A2 (fr) 2004-07-20 2005-07-20 Methode et dispositif pour detecter une fuite dans un conditionnement

Country Status (2)

Country Link
EP (1) EP1779082A2 (fr)
WO (1) WO2006009442A2 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ITPD20110150A1 (it) * 2011-05-12 2012-11-13 Eng Service S R L Apparato per il rilevamento di perdite di un componente a tenuta ed un relativo processo di rilevamento
CN103257022B (zh) * 2013-04-24 2015-06-17 东莞市奇易电子有限公司 密封测试仪及密封测试方法
DE102017005842A1 (de) 2017-06-21 2018-12-27 Heuft Systemtechnik Gmbh Verfahren und Vorrichtung zur Leck-Detektion in Druckbehältern

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3824839A (en) * 1971-09-24 1974-07-23 Varian Associates Leak detecting system and method for passing a measured sample of gas to a leak detector
DE3936163A1 (de) * 1989-10-31 1991-05-02 Fraunhofer Ges Forschung Verfahren und vorrichtung zur messung der dichtigkeit hermetisch abgeschlossener behaelter
GB9403184D0 (en) * 1994-02-18 1994-04-06 Boc Group Plc Methods and apparatus for leak testing
US5889199A (en) * 1997-05-13 1999-03-30 Jaesent Inc. Portable leak detector
JP2000002615A (ja) * 1998-06-16 2000-01-07 Ikuno Seisakusho:Kk 高圧ガス容器の気密検査方法およびその装置
DE10235878A1 (de) * 2002-01-18 2003-07-31 Inficon Gmbh Lecksuchverfahren und -einrichtungen

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2006009442A3 *

Also Published As

Publication number Publication date
WO2006009442A3 (fr) 2006-03-23
WO2006009442A2 (fr) 2006-01-26

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