Patent Application
20230417618
The present invention relates to a method of leak testing a component and to a leak testing apparatus.
Components which contain liquid or gas and cannot be permitted to leak by more than a certain threshold amount may be subject to leak testing to assess the integrity of the components. Components that, in use, contain a functional fluid can be subject to leak testing after being filled with the functional fluid. Leak testing a component prior to providing the functional fluid is undesirable because the state of the integrity of the components could change between the leak test and providing the functional fluid. Components from a wide variety of applications may be subject to leak testing, for example medical vials and batteries. The sensitivity of conventional leak testing apparatus is relatively limited, particularly when the component is filled with a functional fluid. This is undesirable because even very small leaks may be hazardous if the liquid contained in the component is toxic. In addition, the presence of a leak may allow ingress of fluid into a component, and this may cause contamination of the fluid in the component. This is particularly undesirable if the component is a medical vial (or other container) which contains a medical fluid.
It is an object of the present invention to provide leak testing which addresses the problem above or another problem associated with the prior art.
In a first aspect of the present invention there is provided a method of leak testing a component containing a functional fluid. The method comprises positioning the component within a vessel, the vessel defining a chamber; reducing the pressure of a fluid in the chamber; supplying a carrier fluid to the chamber and simultaneously pumping fluid from the chamber through a fluid detection device; and using the fluid detection device to monitor for the presence of the functional fluid.
The functional fluid may be a functional liquid. The same pump may be used to reduce the pressure of the fluid inside the vessel and to pump fluid from the vessel through the fluid detection device. The supply of carrier fluid to the chamber and pumping of fluid from the chamber through a fluid detection device may commence upon the pressure of the fluid in the chamber reaching a predetermined value. Although a vacuum pump is used, the predetermined value need not be zero.
The step of supplying the carrier fluid to the chamber and simultaneously pumping fluid from the chamber through a fluid detection device and monitoring for the presence of the functional fluid may occur subsequent to the step of reducing the pressure of the fluid inside the chamber.
The carrier fluid supply may be a supply of carrier gas. The component may comprise an internal volume. The internal volume of the component may be sealed from the chamber. The fluid detection device may be a mass spectrometer.
Throughout this document, the term ‘functional fluid’ may be understood to mean a fluid contained within the component being tested by the leak testing apparatus that allows the component to serve its purpose or perform a function.
Since the method comprises supplying a carrier fluid to the chamber, if fluid leaks out of the component, the leaked fluid forms a mixture with the carrier fluid. The mixture is then transported to and through the fluid detection device. The fluid detection device can then monitor the fluid for the presence of the functional fluid that has leaked from the component. This advantageously allows detection of smaller leaks compared to if the carrier fluid were not supplied to this chamber. If the carrier fluid were not supplied to the chamber, the leaked fluid alone would not be in sufficient abundance to be transported out of the chamber and to the fluid detection device. Since a carrier fluid is provided to form a mixture with the leaked fluid, the total fluid abundance within the chamber is increased compared to if the carrier fluid were not provided to the chamber. This therefore allows the leaked fluid to be transported to the fluid detection device.
In addition, since a mixture is formed with the carrier fluid and with the leaked fluid, identification of leaked fluid by the fluid detection device is advantageously enhanced. This is because a carrier fluid of known characteristics can be supplied to the chamber. Therefore, the data obtained with the fluid detection device will include the results that are caused by the known carrier fluid. Since the characteristics of the carrier fluid are known, such results can be disregarded from the set of results for the purpose of identifying component leaks.
In addition, since the method comprises supplying a carrier fluid to the chamber, the pressure of the fluid in the chamber is advantageously stabilised. Once a predetermined pressure of the fluid in the chamber has been achieved, fluid is pumped from the chamber through the fluid detection device. In the absence of a carrier fluid supply, the pressure of the fluid in the chamber would reduce as the fluid in the chamber is pumped through the fluid detection device. The reduction of the pressure of the fluid in the chamber during testing is undesirable as the component being tested would not be subjected to a consistent testing pressure, which can result in flawed test results. In particular, the gas detection device may have an optimum operating pressure range, below which the accuracy of gas detection is reduced. Since the carrier fluid supply stabilises the pressure of the fluid in the chamber, the gas detection device may remain within its optimum operating pressure range throughout the test. This allows better testing accuracy than would otherwise be achieved.
The product of the pressure and the velocity of the supply of carrier gas may be within 5% of the product of the pressure and the velocity of the fluid at the fluid detection device.
When the flow rate of the supply of carrier fluid is within 5% of the flow rate of fluid through the fluid detection device, the pressure of the fluid in the chamber of further stabilised, providing improved testing conditions.
The product of the pressure and the velocity of the supply of carrier gas may generally match the product of the pressure and the velocity of the fluid at the fluid detection device.
The method may further comprise modulating the flow rate of fluid through the fluid detection device.
The flow rate of fluid through the fluid detection device may be modulated using a regulator valve.
Since the flow rate of carrier fluid into the chamber can be modulated, the flow rate of carrier fluid into the chamber can advantageously be modulated to provide a desired differential between the flow of carrier fluid into the chamber and the flow of fluid out of the chamber to the fluid detection device. This improves the stability of the pressure of the fluid in the chamber.
The pressure of the fluid in the chamber may be reduced using a vacuum pump.
The term ‘vacuum pump’ may be understood to refer to any pump that is suitable to reduce the pressure of a fluid in the chamber. By way of example, the vacuum pump may be a scroll pump or a centrifugal pump. More than one vacuum pump may be used to reduce the pressure of the fluid in the chamber.
The fluid may be pumped through the fluid detection device using a second pump.
In a second aspect of the present invention there is provided a leak testing apparatus for leak testing a fluid containing component at a reduced pressure. The apparatus comprises a vessel that defines a chamber, the vessel having a carrier fluid inlet; a fluid detection device in fluid communication with the chamber; and a pumping system that is configured to reduce the pressure of the fluid in the chamber and to pump fluid from the chamber through the fluid detection device.
It will be appreciated that the advantages discussed in relation to the first aspect of the invention apply to this aspect of the invention mutatis mutandis.
The apparatus may further comprise a controller. The controller may be configured to control the components of the leak testing apparatus.
The apparatus may further comprise a carrier fluid supply that is connected to the carrier fluid inlet.
The carrier fluid supply may be directly or indirectly connected to the carrier fluid inlet.
The carrier fluid supply may be a carrier fluid vessel. The carrier fluid may be a gas. The carrier fluid vessel may be a carrier gas vessel.
The apparatus may further comprise a regulator valve. The regulator valve may be located downstream of the carrier fluid vessel and upstream of the carrier fluid inlet.
The regulator valve may be manually controllable. The regulator valve may be controlled by the controller.
The controller may be configured to activate the carrier fluid supply when the fluid in the chamber has reached a predetermined threshold pressure.
Throughout this document, the terms ‘vacuum’, ‘evacuated state’ and the like may be interpreted as referring to a volume that is at a significantly reduced pressure relative to the pressure of the functional fluid contained within the component. This can be referred to as the pressure differential. The pressure differential may be 1 mbar.
The pumping system may be configured to pump fluid from the chamber through the fluid detection device such that the product of the pressure and the velocity of the fluid at the fluid detection device is within 5% of the product of the pressure and the velocity of the fluid at the carrier fluid inlet.
The pumping system may comprise a vacuum pump that is configured to reduce the pressure of the fluid in the chamber.
The pumping system may comprise a second pump that is configured to pump fluid from the chamber through the fluid detection device.
The fluid detection device may be configured to draw fluid out of the chamber and monitor the fluid for the presence of the functional fluid and/or for an abnormal background reading while the vacuum pump is operating.
In a third aspect of the present invention there is provided a method of leak testing a component containing a functional fluid. The method comprises positioning the component within a chamber of a vessel; then reducing the pressure of the fluid in the chamber using a vacuum pump; and simultaneously pumping fluid from the chamber through a fluid detection device using a pump of the fluid detection device and monitoring the fluid for the presence of the functional fluid and/or for an abnormal background fluid.
Since fluid is drawn through the fluid detection device while the pump is operating, the fluid detection device can detect any abnormalities in the composition of the fluid present in the chamber before commencement of the leak testing procedure. This may be referred to as an abnormal background fluid. An abnormal background fluid gives rise to an abnormal background reading. An abnormal background fluid can be, for example, a liquid that has leaked onto an interior surface of the chamber prior to commencing the test. This leaked liquid will be vaporised as the pressure of the fluid in the chamber is decreased by the vacuum pump. Detecting the vapour that results from vaporisation of the leaked liquid while the vacuum pump is operating allows an abnormal reading to be identified by the fluid detection device earlier during the leak testing procedure compared to if the fluid detection device were isolated from the chamber while the vacuum pump was operating and then brought into fluid communication once the pump has brought the pressure of the fluid in the chamber to a predetermined threshold pressure. Early identification of an abnormal background reading therefore increases the throughput of the apparatus compared to if the fluid detection device were isolated from the chamber while the first pump is operating.
Furthermore, since the fluid is passed through the fluid detection device and monitored for the presence of an abnormal background reading and/or for the presence of the functional fluid of the component while the pressure of the fluid in the chamber is being reduced, leaks of the component can be detected earlier in the leak testing process compared to if the fluid detection device were only to be activated once the step of reducing the pressure of the fluid in the chamber is complete. Advantageously, this increases the rate at which components can be tested because the process can be stopped as soon as a leak is detected, compared to if the fluid in the chamber was only drawn to the fluid detection device after completion of the step of reducing the pressure of the fluid in the chamber.
The method may further comprise modulating the flow of fluid through the fluid detection device.
The flow of fluid through the fluid detection device may be modulated such that the pressure of the fluid at the fluid detection device is within 5% of the pressure of the fluid in the chamber.
The flow of fluid into the fluid detection device may be modulated using a regulator valve.
The fluid in the chamber may be drawn to the fluid detection device via a bypass line. The bypass line may bypass a second pump.
The method may further comprise, subsequent to reducing the pressure of the chamber, supplying a carrier fluid to the chamber and simultaneously pumping the fluid in the chamber to the fluid detection device with a second pump.
The method may further comprise, subsequent to reducing the pressure of the chamber, isolating the bypass line from the chamber and pumping the fluid in the chamber to the fluid detection device using the second pump.
In a fourth aspect of the present invention there is provided a leak testing apparatus for leak testing a fluid containing component at a reduced pressure. The apparatus comprises a vessel that defines a chamber; a vacuum pump, an inlet of the vacuum pump being connected to the vessel; and a fluid detection device connected to the vessel, the fluid detection device comprising a pump. The fluid detection device is configured to pump fluid out of the chamber using the pump and monitor the fluid for the presence of the functional fluid and/or for an abnormal background fluid the fluid, the fluid detection device operating simultaneously with the vacuum pump.
It will be appreciated that the advantages discussed in relation to the third aspect of the invention apply to this aspect of the invention mutatis mutandis.
It will be appreciated that the inlet of the vacuum pump may be directly or indirectly connected to the chamber.
The apparatus may further comprise a controller. The controller may be configured to control the components of the leak testing apparatus.
The apparatus may further comprise a regulator valve. The regulator valve may be located upstream of the fluid detection device.
Since the apparatus comprises a regulator valve, the flow of fluid from the chamber to the fluid detection device can be advantageously regulated in order to stabilise and/or limit the rate of flow of fluid to the fluid detection device. This reduces the likelihood that the fluid detection device will become saturated. Saturation of the fluid detection device occurs when a large amount of fluid passes through the fluid detection device. Saturation of the fluid detection device is undesirable because the user of the apparatus must wait for the fluid detection device to clear before a further test can be performed.
The controller may be configured to control the regulator valve such that the pressure of the fluid at the fluid detection device is within 5% of the pressure of the fluid in the chamber.
The regulator valve may be a butterfly valve.
The apparatus may further comprise a second pump. An inlet of the second pump may be connected to the chamber. An outlet of the second pump may be connected to the fluid detection device.
The inlet of the second pump may be directly or indirectly connected to the chamber. The outlet of the second pump may be directly or indirectly connected to the fluid detection device.
The capacity of the second pump may be less than that of the vacuum pump.
The apparatus may further comprise a bypass line. The bypass line may be in fluid communication with the chamber and with the fluid detection device. The bypass line may bypass the second pump.
Where the apparatus comprises a bypass line that bypasses the second pump, the second pump can advantageously be isolated from the chamber while the first pump is operating. This allows fluid to be drawn into the fluid detection device by the fluid detection device itself. The capacity of the second pump may be too large to use without risking saturating the fluid detection device.
While the vacuum pump is operating, the second pump may be fluidly isolated from the chamber, and the fluid detection device may be in fluid communication with the chamber via the bypass line.
The chamber may comprise a carrier fluid inlet
The apparatus may further comprise a carrier fluid vessel. The carrier fluid vessel may be connected to the carrier fluid inlet.
Upon receiving a signal from the fluid detection device that the amount of functional fluid has reached a predetermined level, the controller may be configured to deactivate operation of the vacuum pump.
The controller may be configured to isolate the second pump from the chamber while the vacuum pump is operating.
When the pressure of the fluid in the chamber reaches a predetermined magnitude, the controller may be configured to isolate the bypass line from the chamber and bring the second pump into fluid communication with the chamber.
Features of different aspects of the invention may be combined together.
Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying Figures, in which:
The vessel 4 defines a chamber 6. The chamber 6 is the internal volume that is defined by the vessel 4. The vessel 4 may be any suitable vessel that allows the chamber 6 to be sealed from the external environment. It will, however, be appreciated that the chamber 6 may be in fluid communication with the external environment via one or more components of the leak testing apparatus.
The leak testing apparatus 2 further comprises a vacuum pump 8. The term ‘vacuum pump’ may be understood to refer to any pump that is suitable to reduce the pressure of fluid in the chamber 6. The vacuum pump 8 may for example be a centrifugal pump, rotary vane pump, scroll pump or diaphragm pump. The vacuum pump 8 be referred to as a ‘rough pump’ (so called because of the high flow capacity of the pump). An inlet of the vacuum pump 8 is connected to the chamber via a first conduit 10. The first conduit 10 extends from a first fluid outlet 14 of the vessel 4 to the inlet of the vacuum pump 8. This allows the flow of fluid from the chamber 6 through the first conduit 10 to the vacuum pump 8. An outlet (not shown in
The first conduit 10 is provided with a first isolation valve 12. The first isolation valve 12 is located between the first fluid outlet 14 of the vessel 4 and the inlet of the vacuum pump 8. That is to say, the first isolation valve 12 is located upstream of the inlet of the vacuum pump 8. Although the first conduit 10 is provided in two sections, i.e. a first section extending between the first fluid outlet 14 and the first isolation valve 12 and a second section extending between the first isolation valve and the inlet of the vacuum pump 8, the first conduit is referred to as a single component. This principle also applies to the other conduits of the leak testing apparatus 2, which will be introduced below. Any suitable type of valve may be used for the first isolation valve 12. For example, the first isolation valve 12 may be a rocker valve, bellows sealed vacuum valve, non-bellows sealed vacuum valve, butterfly valve, gate valve or a diaphragm valve. The first isolation valve 12 may be electromechanically or pneumatically controllable. The first isolation valve 12 may be a solenoid valve.
When in an open position, the first isolation valve 12 allows the flow of fluid. When in a closed position, the first isolation valve 12 prevents the flow of fluid. This principle applies to the other isolation valves of the leak testing apparatus 2 that will be introduced below. Therefore, the first isolation valve 12 allows the vacuum pump 8 to be isolated from the chamber 6.
The vessel 4 comprises a carrier fluid inlet 16. The leak testing apparatus 2 further comprises a carrier fluid vessel 18. The carrier fluid vessel 18 contains a carrier fluid. The fluid contained in the carrier fluid vessel 18 is pressurised. The carrier fluid that is contained within the carrier fluid vessel 18 may be any suitable fluid. The carrier fluid may be a carrier gas. The carrier gas may be, for example, nitrogen, carbon dioxide, or dry air. An outlet (not shown in
The second conduit 20 is provided with a second isolation valve 22. The second isolation valve 22 may be any suitable type of valve. For example, the second isolation valve 22 may be a rocker valve, bellows sealed vacuum valve, non-bellows sealed vacuum valve, butterfly valve, gate valve or a diaphragm valve. The second isolation valve 22 may be electromechanically or pneumatically controllable. The second isolation valve 22 may be a solenoid valve. The second isolation valve 22 allows the carrier fluid vessel 18 to be isolated from the chamber 6.
A first regulator valve 24 is also provided to the second conduit 20. The first regulator valve 24 may be any suitable type of valve. For example, the first regulator valve may be a needle valve or a butterfly valve. The first regulator valve 24 may be electromechanically, pneumatically, or manually controllable. The purpose of the first regulator valve 24 is to set the rate at which the carrier fluid flows from the carrier fluid vessel 18 into the chamber 6. In the present embodiment, the degree to which the first regulator valve 24 is open is set prior to commencement of a leak test and remains unchanged throughout the test. However, in other embodiments, the first regulator valve 24 can be used to modulate the flow of fluid through it during a test by varying the degree to which it is open. Modulation of the first regulator valve 24 varies the rate at which fluid can flow through the first regulator valve. This principle applies to the other regulator valve of the leak testing apparatus, which will be introduced below.
The first regulator valve 24 is located between the second isolation valve 22 and the outlet of the carrier fluid vessel 18. That is to say, the first regulator valve 24 is located downstream of the outlet of the carrier fluid vessel 18 and upstream of the second isolation valve 22. In other, non-depicted, embodiments, the first regulator valve may be located downstream of the second isolation valve. That is to say, the second isolation valve may be located between the outlet of the carrier fluid vessel and the first regulator valve.
The leak testing apparatus 2 further comprises a fluid detection device 26. The fluid detection device 26 may be, for example, a mass spectrometer. The fluid detection device 26 is able to monitor a fluid flowing through the fluid detection device for the presence of one or more fluids, as will be discussed in more detail below. The fluids detected by the fluid detection device 26 may be a gas, a vapour and/or a liquid. An inlet (not shown in
The fluid detection device 26 further comprises a pressure gauge (not shown in the figures). This allows the fluid detection device 26 to take readings of the pressure of the fluid passing through it and pass this data to a user and/or to a controller, as will be discussed in more detail below.
The inlet of the fluid detection device 26 is in fluid communication with the chamber 6 via a third conduit 28. The third conduit 28 connects to the vessel 4 at a second fluid outlet 36. A bypass conduit 30 is provided that bypasses a portion of the third conduit 28. The bypass conduit 30 may also be referred to as a bypass line. The bypass conduit 30 is connected to the third conduit 28 at a first junction 31 and a second junction 33. The second junction 33 is located downstream of the first junction 31. The portion of the third conduit 28 that is bypassed by the bypass conduit may be referred to as a direct portion 32 of the third conduit 28. Therefore, the direct portion 32 is the portion of the third conduit 28 that is located between the first junction 31 and the second junction 33.
A second pump 34 is provided to the third conduit 28. The second pump 34 may be referred to as a fine pump. This is because the capacity of the second pump 34 is lower than that of the vacuum pump 8. The second pump 34 is located between the first junction 31 and the second junction 33. An inlet (not shown in
A third isolation valve 38 is provided to the direct portion 32 of the third conduit 28. The third isolation valve 38 is located upstream of the second pump 34 and downstream of the first junction 31. Flow of fluid through the direct portion 32 is prevented by the third isolation valve 38 when the third isolation valve is in the closed position. The third isolation valve 38 may be any suitable type of valve. For example, the third isolation valve 38 may be a rocker valve, bellows sealed vacuum valve, non-bellows sealed vacuum valve, butterfly valve, gate valve or a diaphragm valve. The third isolation valve 38 may be electromechanically or pneumatically controllable. The third isolation valve 38 may be a solenoid valve.
A fourth isolation valve 40 is provided to the bypass conduit 30. The fourth isolation valve 40 is located downstream of the first junction 31 and upstream of the second junction 33. Flow of fluid through the bypass conduit 30, i.e. from the first junction 31 to the second junction 33, is prevented by the fourth isolation valve 40 when the fourth isolation valve is in the closed position. The fourth isolation valve 40 may be any suitable type of valve. For example, the fourth isolation valve 40 may be a rocker valve, bellows sealed vacuum valve, non-bellows sealed vacuum valve, butterfly valve, gate valve or a diaphragm valve. The fourth isolation valve 40 may be electromechanically or pneumatically controllable. The fourth isolation valve 40 may be a solenoid valve.
A second regulator valve 42 is provided to the third conduit 28. The second regulator valve 42 is configured to modulate the flow of fluid through the third conduit 28 (and through the bypass conduit 30 when the fourth isolation valve 40 is open). The second regulator valve 42 is located upstream of the first junction 31. The second regulator valve 42 is located downstream of the second fluid outlet 36 of the vessel 4. The second regulator valve 42 may be any suitable type of valve. For example, the second regulator valve 42 may be a high-speed valve. For example, the second regulator valve 42 may be a butterfly valve. The second regulator valve 42 may be electromechanically or pneumatically controllable. The second regulator valve 42 may be a solenoid valve.
The leak testing apparatus 2 further comprises a pressure gauge 46. The pressure gauge 46 allows the pressure of the fluid in the vessel 4 to be determined. The pressure gauge 46 may be digital or analogue.
Operation of the leak testing apparatus 2 will now be discussed. Operation may be controlled by the controller 44. Alternatively, operation may be controlled by a user (for example if no controller is present). Operation of the leak testing apparatus 2 generally comprises two stages. The first stage of operation is an evacuation and transient fluid monitoring stage. The second stage of operation is a steady state fluid monitoring stage. As discussed above, the component 5 being tested with the leak testing apparatus 2 can contain a functional fluid during operation of the leak testing apparatus. The functional fluid may be, for example, the electrolyte fluid of a battery, or medicine contained within a vial or pre-filled syringe. If the component 5 does leak during the leak test operation, the functional fluid will vaporise upon exiting the component. This is due to the low pressure of the chamber 6. The vaporised fluid can be referred to as a ‘tracer fluid’.
The vacuum pump 8 and the second pump 34 may be active throughout operation of the leak testing apparatus 2. Whether or not fluid flows through the vacuum pump 8 or the second pump 34 is dependent upon the position of the first isolation valve 12 and the third isolation valve 38 respectively. When the vacuum pump 8 or the second pump 34 is in fluid communication with the chamber 6 (i.e., because the first isolation valve or the third isolation valve 38 is open), that pump is said to be operating.
The position of the first regulator valve 24, i.e., the degree to which the first regulator valve is open, is generally set prior to commencing a leak test. The position of the first regulator valve 24 is set such that the pressure at which the carrier fluid is provided to the chamber 6 corresponds with the pressure required to vaporise the functional fluid of the component 5. If the pressure at which the carrier fluid is supplied is too high, the pressure of the fluid inside the chamber may be be too high to allow vaporisation of the functional fluid of the component 5. If the pressure at which the carrier fluid is supplied is too low, the pressure of the fluid in the chamber 6 may not be sufficiently high to allow the fluid in the chamber to be pumped out by the second pump 34. In some embodiments, the position of the first regulator valve may be varied by the controller 44 during leak testing.
The pumping speed of the second pump 34 may be set prior to commencement of the test such that the speed of the flow of fluid through the fluid detection device 26 is optimal. The pumping speed of the second pump 34 may also be set based upon at least the pressure that the carrier fluid is supplied to the chamber 6. If the pumping speed of the second pump 34 is too high, the pressure of the fluid in the chamber 6 falls. This would impair the ability of the second pump 34 to pump fluid from the chamber 6 and through the fluid detection device 26. As a result, the results of the leak test would be impaired. If the pumping speed of the second pump 34 is too low, an insufficient amount of fluid would pass through the fluid detection device 26 and, again, the results of the leak test would be flawed. The pumping speed of the second pump 34 may be selected such that a sufficient amount of fluid is passed through the fluid detection device 26 and that the pressure of the fluid in the chamber 6 is stable.
The pump of the fluid detection device 26 is also active throughout operation of the leak testing apparatus. Whether or not the fluid detection device 26 is able to pump fluid from the chamber 6 and through itself is dependent upon the position of the third and/or fourth isolation valves 38, 40 and of the second regulator valve 42. If the second regulator valve 42 is at least partially open and either of the third or fourth isolation valves 38, 40 are open, then the fluid detection device 26 is said to be operating because it is in fluid communication with the chamber 6.
The first stage of operation will now be discussed with reference to
At step 100, the component 5 is positioned in the vessel 4 by a user. At step 102, the user seals the chamber 6 from the external environment, for example, by closing a lid (not shown in
The operation then continues to steps 104a and 104b which occur simultaneously (this is the start of the evacuation and fluid monitoring stage). At step 104a, the pressure of the fluid inside the vessel 4 is reduced. The first isolation valve 12 is open at this stage in operation, as discussed above. Therefore, the vacuum pump 8 is able to pump fluid from the chamber 4 to an external volume (not shown in the Figures). This pumping action of the vacuum pump 8 reduces the pressure of the fluid in the chamber 6. At step 106, the controller 44 assesses whether the pressure of the fluid in the chamber 6 is less than or equal to a threshold value. To do this, the controller 44 compares pressure data received from the pressure gauge 46 against the threshold value. If the pressure of the fluid in the chamber 6 is greater than the threshold value, operation of the vacuum pump 8 continues. If the pressure of the fluid in the chamber 6 is less than or equal to the threshold value, the operation proceeds to step 108, at which point the operation proceeds to the second stage of operation (the steady state leak detection stage). The threshold value may be based upon the pressure, or other characteristic, of the functional fluid of the component 5. The threshold pressure is less than the pressure of the functional fluid of the component 5. The pressure differential between the pressure of the functional fluid of the component 5 and the threshold pressure of the fluid in the chamber 6 may be, for example, 1 mbar.
At step 104b, the fluid detection device 26 is operated. This is by virtue of the opening of the fourth isolation valve 40 and of the second regulator valve 42, discussed above. The fluid detection device 26 is then able to pump fluid from the chamber 6. Since the third isolation valve 38 is closed at this stage, the direct portion 32 of the third conduit 28 is isolated from the chamber 6 and so fluid is pumped to the fluid detection device 26 via the bypass conduit 30. As discussed above, the fluid detection device 26 comprises a pump that pumps fluid from the chamber 6 to the inlet of the fluid detection device and through the fluid detection device. In some embodiments, the fluid can be pumped to the fluid detection device 26 via the direct portion 32 of the direct conduit 28. In such an embodiment, the second pump 34 may or may not be activated. That is to say, the fluid in the chamber 6 is can be pumped to the fluid detection device 26 via the direct portion 32 by the pumping action of the second pump 34 and/or the pumping action of the fluid detection device 26. In these embodiments, the bypass conduit 30 need not be provided.
While the fluid detection device 26 is operating, the operation proceeds to step 110. At step 110, the flow of fluid into the fluid detection device 26 is modulated. The flow of fluid into the fluid detection device 26 is modulated using the second regulator valve 42. Modulation using the second regulator valve 42 refers to the varying of the rate of the flow of fluid into the fluid detection device 26. This can be achieved by varying the degree to which the second regulator valve 42 is open. To do this, the controller 44 receives data from the pressure gauge 46 of the chamber 4 and from the pressure gauge of the fluid detection device 26. The controller 44 then sends a signal to the second regulator valve 42 to vary the degree to which the second regulator valve is open such that the pressure of fluid that is being passed through the fluid detection device 26 generally matches the pressure of the fluid in the chamber 6. Therefore, as the pressure of the fluid in the chamber 6 decreases, the degree to which the second regulator valve 42 is open increases. In some embodiments, the pressure of the fluid flowing through the fluid detection device 26 may be within 5% of the fluid in the chamber 6.
Modulating the flow of fluid into the fluid detection device 26 reduces the likelihood that the fluid detection device 26 becomes saturated with the fluid from the chamber 6. Saturation of the fluid detection device 26 causes delays because it is necessary to wait for the fluid detection device to clear before commencing further leak tests. In addition, this prevents the pressure of the fluid that is passing through the pump of the fluid detection device 26 from building up. A build-up of pressure of the fluid in the pump of the fluid detection device 26 can cause the pump to fail, which is undesirable as permanent damage to the fluid detection device may occur as a result.
Also at step 110, the fluid detection device 26 monitors the fluid flowing through it for the presence of the functional fluid. The data obtained through the monitoring of the fluid passing through the fluid detection device 26 is sent to the controller 44. This data is then assessed at step 112 to determine whether a leak or abnormal reading is detected. If no leak or abnormal reading is detected, the operation returns to step 110. If a leak or abnormal reading is detected, operation proceeds to step 114. At step 114, the controller stops operation of the leak testing apparatus 2 and issues an alert to the user. Whichever of steps 108 and 112 occurs first takes precedence.
Advantageously, the fluid detection device 26 monitors the fluid that is passing through it while the vacuum pump 8 is operating (evacuation and fluid monitoring occur simultaneously). This means that the fluid detection device 26 is able to detect an abnormal background fluid and/or a leak of fluid from the component 5 being tested earlier in the testing process. This is compared to if the fluid detection device was only operated once the pressure of the fluid in the chamber 6 had been reduced to a predetermined value.
The term ‘background fluid’ refers to the fluid that is present inside the vessel 4 prior to commencing operation of the leak testing apparatus 2. An abnormal background fluid may be caused by, for example, a spill of fluid on an internal surface of the vessel 4. An abnormal background fluid gives rise to an abnormal background reading. That is, the reading obtained by the monitoring of the fluid from the chamber 6 with the fluid detection device 26 while the vacuum pump 8 is operating.
The component 5 being tested may begin to leak a fluid prior to the pressure of the fluid in the chamber 6 reaching the threshold value. Therefore, since the fluid detection device 26 is able to monitor the fluid from the chamber 6 while the vacuum pump 8 is operating, component leaks can be identified earlier compared to if the fluid detection device were isolated from the chamber until the predetermined pressure of the fluid in the chamber had been reached.
The second stage of operation of the leak testing apparatus 2 will now be discussed with reference to
Next, at step 206, the controller 44 sends a signal to the second regulator valve 42 to move the second regulator valve to the fully open position.
The operation of the leak testing apparatus 2 then proceeds to step 208. At step 208, fluid is pumped through the fluid detection device 26. This is by virtue of the third isolation valve 38 and the second regulator valve 42 being open. Therefore, the second pump 34 operates during step 208. The second pump 34 pumps fluid from the chamber 6 through the second fluid outlet 36, the third conduit 28, via the direct portion 32, and through the fluid detection device 26. Passing the fluid from the chamber 6 through the fluid detection device 26 allows the fluid detection device to monitor the fluid for the presence of the functional fluid of the component 5. Data relating to the monitoring of the fluid passing through the fluid detection device 26 is then sent from the fluid detection device to the controller 44. The data relating to the monitoring of the fluid from the chamber 6 will include the results that are caused by the carrier fluid. Advantageously, since the characteristics of the carrier fluid are known, the results that correspond with the carrier fluid can be disregarded from the data, allowing simple identification of a leak from the component 5.
As discussed above, the position of the first regulator valve 24 is generally set prior to commencing a leak test. However, step 208 may also include modulating the flow rate of carrier fluid into the chamber 6. The flow rate of fluid through the second pump 34 is measured and the data is sent to the controller 44. The controller 44 then controls the first regulator valve 24 to adjust the flow rate of carrier fluid into the chamber 6 based on the flow rate of the fluid from the chamber through the second pump 34. The flow of carrier fluid through the first regulator valve 24 and into the chamber 6 can be modulated (i.e. adjusted) such that the product of the pressure and the velocity of the carrier fluid at the carrier fluid inlet 16 generally matches the product of the pressure and the velocity of the fluid that flows through the second fluid outlet 36. In some embodiments, the product of the pressure and the velocity of the carrier fluid generally may be within 5% of the product of the pressure and the velocity of the fluid that flows through the second fluid outlet 36.
Operation then proceeds to step 210. Step 210 occurs simultaneously with step 208. At step 210, the controller 44 uses the data relating to the monitoring of the fluid from the chamber 6 to determine whether the component 5 being tested is leaking fluid. If a leak is identified, operation proceeds to step 220, which ends operation of the leak testing apparatus 2. Upon detection of a leak, the controller 44 sends a signal to the third isolation valve 38 to close the third isolation valve. This protects the fluid detection device from being saturated by the leaked fluid. The controller 44 sends the data obtained during the test to a user interface (not shown in the Figures) to allow the data to be viewed by a user. The data obtained during the test may include data obtained from the fluid detection device 26, from the pressure gauge 46, the time elapsed during the test, the date of the test and/or information allowing the component(s) being tested to be identified (such as a batch number). The data may also include a leak rate of the component(s) 5. The leak rate being the rate at which the functional fluid is egressing out of the component. The data may include an alert 216 that a leak has been identified.
If a leak is not identified during step 210, operation proceeds to step 214. At step 214, the controller 44 determines whether a predetermined amount of time has elapsed. If the predetermined amount of time has elapsed, operation proceeds to step 220 to end operation of the leak testing apparatus 2. Again, the controller 44 then sends the data obtained by the fluid detection device 26 during the test to a user interface to allow the data to be viewed by a user. The data may include an output 218 to identify that the leak test has been passed. If the predetermined amount of time has not elapsed, step 208 continues. The predetermined amount of time may be less than or equal to 10 seconds. The predetermined amount of time may be less than or equal to 5 seconds.
Since the component 5 being tested contains a functional fluid, if the component has a defect (not shown in the Figures) through which fluid can flow, the fluid that is contained by the component will be drawn through the defect and into the chamber. This is because the pressure in the chamber 6 is less than the pressure of the fluid that is contained within the component 5 being tested. As a result, the fluid that is contained within the component diffuses from the component and into the chamber 6, via the defect. Once the leaked fluid enters the chamber 6, it is vaporised because of the reduced pressure of the fluid in the chamber. The vapour may be referred to as a tracer gas or tracer vapour. Since a carrier fluid is supplied to the chamber 6, the leaked fluid mixes with the carrier fluid and the mixture is transported to the fluid detection device 26 by the second pump 34. In the absence of the carrier fluid, the leaked fluid may not be in sufficient abundance to be transported to the fluid detection device 26 by the second pump 34. Therefore, the supply of carrier fluid to the chamber 6 increases the total abundance of fluid in the vessel 4, allowing the fluid in the chamber to be transported to the fluid detection device 26. The supply of carrier fluid therefore advantageously allows the detection of smaller leaks compared to a leak testing apparatus that does not supply a carrier fluid during leak detection.
The component 5 may be any component that contains a fluid in its normal configuration. The component may be, for example, a battery or a pre-filled syringe. Operation of the leak testing apparatus 2 is not limited to testing a single component at a time. It is possible to place multiple components in the chamber for testing. This increases the throughput (i.e. the total number of components that can be tested in a given time period) of the leak testing apparatus 2. Testing multiple components at once may be particularly advantageous where it is known that the likelihood of a component having a leak is low. For example, this may be suitable where approximately one in one thousand components or more is expected to have a leak. If a leak is detected when testing multiple components at once, the components can then be tested individually to assess which component(s) have a leak.
It will be appreciated that the first stage of operation can be performed independent of the second stage of operation. It will also be appreciated that the second stage of operation can be performed independent of the first stage of operation. That is to say, a leak detection apparatus can perform fluid monitoring and evacuation simultaneously without then supplying a carrier fluid to a chamber of the leak detection apparatus. Similarly, a leak detection apparatus can supply a carrier fluid during a steady state fluid monitoring stage, without having performed fluid monitoring during an evacuation stage.
An alternative embodiment of a leak testing apparatus 2′ is shown in
Although not depicted, the leak testing apparatus 2′ further comprises a controller that is in communication with the components, in particular the valves and pumps, of the leak testing apparatus. The method of operation of the leak testing apparatus 2′ shown in
The leak testing apparatus 2″ comprises an evacuation conduit 52″. The evacuation conduit 52″ is connected to the third conduit 28″ downstream of the pump 50″. The evacuation conduit 52″ is connected to the direct portion 32″ of the third conduit 28″. However, the evacuation conduit 52″ can be connected to the third conduit 28″ at any point that is downstream of the pump 50″. An evacuation isolation valve 54″ is provided to the evacuation conduit 52″. The evacuation isolation valve 54″ allows the evacuation conduit 52″ to be isolated from the third conduit 28″ when the evacuation isolation valve 54″ is in the closed position.
The third conduit 28″ is further provided with a fluid detection isolation valve 56″. The fluid detection isolation valve 56″ is located downstream of the point at which the evacuation conduit 52″ is connected to the third conduit 28″. The fluid detection isolation valve 56″ is located upstream of the second junction 33″. The fluid detection isolation valve 56″ allows the fluid detection device 26″ to be isolated from the direct portion 32″ of the third conduit 28″ when the fluid detection isolation valve 56″ is in the closed position.
As with previous embodiments, the leak testing apparatus 2″ comprises a bypass conduit that bypasses the pump 50″. The second regulator valve 42″ of this embodiment is located along the bypass conduit 30″. The second regulator valve 42″ is located upstream of the fourth isolation valve 40″. The third isolation valve 38″ of this embodiment is provided to isolate the pump 50″ from the chamber 6″ between leak tests.
Therefore, the third isolation valve 38″ is in the open position between commencement and finish of a test.
During the first stage of operation of the leak testing apparatus 2″, the evacuation isolation valve 54″ and the fourth isolation valve 40″ are in the open position. In addition, the fluid detection isolation valve 56″ and the second isolation valve 22″ are in the closed position. Operation of the pump 50″ therefore pumps fluid out of the vessel 4″ and to an external volume via the third conduit 28″ and the evacuation conduit 52″. While the pump 50″ is reducing the pressure of the fluid in the chamber 6″, the fluid detection device 26″ is able to draw fluid from the chamber such that the fluid from the chamber is passed through the fluid detection device. The second regulator valve 42″ modulates the flow of fluid through it such that flow of fluid to the fluid detection device is modulated.
During the second stage of operation, the evacuation isolation valve 54″, the second regulator valve 42″ and the fourth isolation valve 40″ are in the closed position. In addition, the fluid detection isolation valve 56″ and the second isolation valve 22″ are in the open positon. This allows the pump 50″ to pump fluid from the chamber 6″ through the third conduit 28″ and to the fluid detection device 26″. Since the second isolation valve 22″ is in the open position, carrier fluid flows into the chamber 6″ from the carrier fluid vessel 18″. The carrier fluid flows into the chamber 6″ via the carrier fluid inlet 16″. The flow rate of the carrier fluid into the chamber 6″ is set using the first regulator valve 24″.
The embodiment depicted in
In some embodiments, upon detection of a leak, operation of the leak testing apparatus 2, 2′, 2″ may continue operation until the readings obtained with the fluid detection device 26 have stabilised. Alternatively, the leak testing apparatus 2, 2′, 2″ may continue operation until a predetermined amount of time has elapsed. The predetermined amount of time where a leak has been detected may be the same as the predetermined amount of time initially set for the test such that the total time taken for the test is unchanged. Alternatively, upon detection of a leak, the leak testing apparatus 2, 2′, 2″ may continue operation for a predetermined amount of time that commences upon detection of the leak. This may result in the leak test being longer or shorter than if a leak had not been detected.
While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. The descriptions above are intended to be illustrative, not limiting. Thus it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016265.7 | Oct 2020 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2021/052660 | 10/14/2021 | WO |
