BE1029702B1 - LEAK DETECTION IN A VACUUM SYSTEM - Google Patents

Abstract

A vacuum system with a leak detection condition, the vacuum system comprising: a process chamber with a volume of fluid to be evacuated; a vacuum pump configured to evacuate the process chamber; at least one pressure sensor configured to measure the pressure within the process chamber; and a recorder programmed to record the pressure measured in the process chamber; wherein, in a leak detection condition, the evacuated process chamber is isolated and the recorder is programmed to record data corresponding to the pressure measured over time within the evacuated process chamber; and wherein the vacuum pump is configured to evacuate the process chamber prior to the leak detection condition and during normal operation of the vacuum system.

Description

LEAK DETECTION IN BEN VACUUM SYSTEM

Scope of application

The present invention relates to vacuum systems and to methods of detecting leaks in vacuum systems. 3 Background

It is generally accepted that in practice vacuum systems can never be completely leak-free, i.e. absolutely vacuum-tight. A leak can be defined as a defect in a vacuum system that allows material to pass from a volume under higher pressure to a volume under lower pressure.

Nevertheless, the leak rate {(e.g. the size of a leak} of a vaculim system must be kept below a sufficient level for a vacuum pump to effectively and efficiently generate and maintain a required pressure in the vacuum system,

Leak rate can be defined as the size of a leak in terms of the amount of material passing through the leak per unit time at a given pressure differential,

The term "Spot" as used herein refers to the general leakage to or from a vacuum system or other test object. A leak can be the result of a single defect in a vacuum system or can be the result of several defects in the vacuum system.

A defect in a vacuum system typically results in material flowing from the outside {higher pressure area} of a vacuum system to the inside (lower pressure area}. For many industrial and experimental processes that operate under vacuum (including low or partial

? BE2021/5857 vacuum) are passed through, it is essential that they are free from contamination due to leakage in the vacuum system.

Therefore, different approaches exist to detect if there is an iek in a vaculum system and how big the iek is,

For example, a separate leak detector, often with its own vacuum pump, can be connected to a vacuum system for a leak detection test.

In another approach, a tracer gas, such as helium (because it is relatively rare in the atmosphere), ì can be supplied outside an evacuated device that includes a nassa spectrometer. If there is a lex, the tracer gas will cross the leak path and be visible to and detected by the mass spectrometer inside the device. Likewise, a device could be pressurized with a tracer gas (at a higher pressure than the outside environment) and it could be observed whether the tracer gas escapes from the Loestel.

The device can also be covered with masking agents or envelopes to confirm a suspected leak. And, while its use is not as widespread as it used to be, air bubbles can also be tested by immersing a pressurized device in a clear liquid, such as water, to determine its presence, size, and often location. , from a leak in Lonen.

For vacuum systems that must be sealed, either under vacuum or filled with a fluid that must not be lost or contaminated by an in-leak,

3 BE2021/5857 very strict standards, and those standards must be regularly checked and maintained throughout the life cycle of the vacuum system. 9 However, existing approaches, including those described above { 5 , are labor and cost intensive, and usually require dedicated leak detection equipment for a leak test, often requiring an experienced specialist to reliably perform a leak test manually,

Thus, the control of the high vacuum tightness standards is a considerable burden, especially when an engineer or other professional must regularly visit each vacuum system on site to test it. Since the manufacture of vacuum pumps and vacuum systems is a highly specialized field, the customer base can van sen producer of vaculum systems are spread over a large geographical area, which increases this burden even more.

Moreover, a well-known phenomenon is the possible presence of a virtual leak in a vacuum system. In other words, a leak - or rather its characteristics - may be detected, even though a vacuum system is sufficiently leak-free / vacuum-tight. A so-called virtual isk can be due to outgassing or the release of trapped gas bubbles that slowly escape over time within a vacuum system, possibly at a certain temperature or at a certain stage of a process,

Consequently, a pressure rise can be detected in an isolated vacuum system that is under vacuum and none

Fight" leak. An engineer who is called to a

4 BE2021/5857 vaculum system Le testing, may mistakenly think that a vacuum system has a leak, when in fact this is not the case. This may require unnecessary effort, resources and system interruptions,

The present invention aims to address these and other problems with the prior art,

Summarytina

Accordingly, in a first aspect, the invention provides a vacuum system having a leak detection condition, the vacuum system comprising: a process chamber having a volume of fluid to be evacuated: a vacuum pump configured to evacuate the process chamber; at least one pressure sensor configured to monitor the pressure in the process chamber; and a recorder programmed to record the pressure measured in the process chamber. In a leak detection condition, the evacuated process chamber is isolated and the recording device is programmed to record data Le corresponding to the pressure measured within the process chamber over time. The 23 vacuum pump is configured to evacuate the process chamber prior to the leak detection condition and during normal use of the vacultim system.

This configuration is particularly advantageous because the recorder is configured to automatically record data (i.e., without separate manual user-initiated intervention} corresponding to the pressure measured in the process chamber over time, so that the recorded data can be are used to determine if there is a leak and the size of the leak that has been detected.

This makes it easier and more accurate to detect the presence and extent of a leak. In particular, a user need not actively monitor or manually record data corresponding to process chamber pressure and elapsed time. The vacuum system is autonomous when it is in the

Specifically, lex detection state is located and configured to automatically detect whether or not a leak is present by plotting the pressure change in the croces chamber over time.

The vacuum system is therefore provided with means for self-detection of the presence of a leak. No separate leak detection device is required,

Advantageously, the vacuum pump is configured to evacuate the process chamber Le prior to the leak detect condition and during normal operation of the vacuum system,

The term "leak detection condition" as used herein refers to a condition in which the process chamber is evacuated and icy, primarily for the purpose of leak detection.

In embodiments, a leak can be defined as a change in pressure measured in the process chamber of at least a few millibars, e.g. 10 mbars or more, per minute.

The term “normal use” as used herein refers to a condition in which the vacuum pump is configured to evacuate the process chamber, i.e. to relieve the pressure in the chamber, for a purpose other than the utmost location detection. for example, the vacuum pump evacuates the process chamber so that the primary function of the process chamber can be performed.

In other words, the vacuum pump is not only configured to evacuate the process chamber as part of a leak detection test, but is also configured to evacuate the process chamber when leak detection is not the reason why the vacuum pump is active. Therefore, in the leak detection state, no vacuum pump other than the one used in normal operation is required, and the vacuum system is thus configured to perform an autonomous leak detection test,

The term "evacuated" as used herein refers to just generating a pressure in the process chamber that is lower than the ambient pressure {(e.g., atmospheric pressure}. For the purposes of the invention, atmospheric pressure means 101.325 Pa unless otherwise stated .

In embodiments, the vacuum pump may be configured to produce an ultra-high vacuum (UHV), i.e. less than 10 -7 mbar, within the process chamber,

In embodiments, the vacuum pump may be configured to produce a high vacuum (10 -3 mbar to 10 -7 mbar) within the process chamber.

In embodiments, the vacuum pump may be configured to produce a medium vacuum (a few mbar to 10 -3 mbar} within the process chamber.

In embodiments, the vacuum pump may be configured to produce a raw vacuum within the process chamber.

In embodiments, the vacuum pump may be a sensor oil or propeller vacuum pump. In embodiments, the

7 BE2021/5857 vacuum pump can be an iurbomolecular pump. In embodiments, the vacuum pump may be a multi-stage vacuum pump,

In embodiments, the vacuum system may include an auxiliary pump, which may also be referred to as a booster pump.

The term "insulated" as used herein refers to a configuration in which fluid communication between the inside of the process chamber and the outside of the process chamber, generally including the vacuum pump, is substantially prevented,

In embodiments, the recorder may be formed as part of the vacuum pump or the process chamber. In embodiments, the recorder may be formed as part of a separate unit, such as a computer or a smart device. in embodiments, the recorder set may be wirelessly connected to one or more parts of the remainder of the vacuum system. For example, the recorder may be wirelessly connected to the or each pressure sensor. In embodiments, the or each pressure sensor may be hardwired to the recorder. In embodiments, the vacuum system may include more than one pressure sensor so that in the event that a first pressure sensor fails, a further pressure sensor is present and configured to measure the pressure within the process chamber,

In embodiments, the recorder may be programmed to calculate one or more characteristics of a detected leak Le. For example, the presence, size, and/or estimated location may be calculated by the recorder based on the recorded data.

In embodiments, the recorder may be programmed to calculate a pressure rise rate based on the recorded pressure change within the process chamber over a period of time,

In embodiments, the recording system may be programmed to calculate a leak rate of the process chamber. A leak rate may be based on the volume of the process chamber (e.g., the internal volume of the evacuated space upstream of the isolation valve) and the recorded data. In embodiments, the recorder may be configured to calculate a speed, dq: based on the following formula: { — y AP

EV AE where V is the volume of the process chamber, and Âp is the change in pressure in the process chamber over the elapsed time a At

In embodiments, the recording set may be configured to take into account one or more properties of the process chamber, for example, the volume of the process chamber or an acceptable leak rate of the process chamber.

In embodiments, the recorder may be configured to take into account one or more properties of a gas, for example atmospheric air, within the process chamber or passing through a wall dis-

3 BE2021/5857 process chamber will be demarcated if there is a defect in the wall. for example, the molar weight, gas constant and/or temperature of the gas can be recorded and taken into account as part of a calculation by ; the recorder,

Thus, in embodiments, the recorder may be configured to calculate a leak rate, du, of the vacuum system Le using the following formula:

Max "Am.

AT di = At where M is the molar mass of the gas, Am the : mass change in g, R the gas constant, T the temperature { of the gas (in Kelvin} and At the elapsed time

For example, for dry air (i.e., air at standard armospheric pressure containing no or negligible traces of water vapor} the molar mass of dry air, M, would be approximately 28.9634 g/mol, the gas constant, EK, would be approximately 8.314 J-K *.mol-! and would the temperature,

T, 293 Kelvin.

In embodiments, the vacuum system may include one or more additional sensors for sensing a

THE more properties of a gas that is present inside and/or outside the process chamber.

In embodiments, the recorder may be programmed to determine whether a pressure change over an elapsed time corresponds to a leak and/or outgassing from the vaoutim system. In other words, the recorder may be configured to the nature of

10 BE2021/5857 to determine the pressure change in the process chamber. For example, if the pressure rise rate is essentially constant and does not stabilize, there may be a real leak.

Conversely, if a pressure rise rate decreases after an initial rise, there may be a virtual leak (or a combination of a real leak and outgassing}. Thus, the vacuum system may be configured to distinguish between a "Vecht" leak, i.e. a fault in a wall delimiting the process chamber, and a virtual leak, and/or a combination of a "Vecht" leak and the evolution of gas from part of the process chamber.

In embodiments, the recording device may be programmed to register Le when at least one of the preset time periods has elapsed and/or: a predetermined pressure change threshold is registered. The recorder may be programmed with a predetermined, i.e., predetermined, period of time to elapse and/or a predetermined pressure change threshold. In embodiments, the recorder may be programmed to stop recording when at least one of these parameters is recorded. The pre-set pressure change threshold may include a pressure value greater than the pressure of the evacuated process chamber indicating an unacceptable leak rate. is. For example, a preset pressure change threshold of 50 to 100 moar{a} may indicate that there is a major leak in the process chamber.

In embodiments, the logging kit may be programmed to record data corresponding to the pressure of the process chamber and the elapsed time Lot only a predetermined period of time has elapsed. in embodiments, the recorder may be programmed to record data corresponding to the pressure of the process chamber and the elapsed time Lot only a preset pressure change threshold has been reached. The preset pressure change threshold may be referred to as the "Delta P- limit”, cf "Ap limit".

In embodiments, the recorder may be programmed to stop recording data when a preset period of time has elapsed or when a preset pressure change threshold has been reached and the recorder stops recording data when the first of these carameters is reached.

As described, the recorder may be programmed to record data until a preset time period has elapsed, i.e. until a maximum pressure rise time has elapsed, and/or until a preset pressure change threshold has been reached. Thus, in embodiments, the pre-set pressure change threshold may not have been reached after the time the pre-set period has elapsed, or alternatively, the pre-set pressure change threshold is reached before the pre-set period has elapsed. In either case, the recorder nevertheless stops the leak detection test and proceeds to record data,

12 BE2021/5857

There is either a preset time period and/or a preset pressure change threshold or both, otherwise leak detection could theoretically continue indefinitely in a leak-free vaculum system.

In embodiments, the vacuum system may further include a; controller. In embodiments, the controller and recorder may be separate entities within the vacuum system. In embodiments the controller and recorder may be part of a single unit, in embodiments the controller may be part of the vacuum pump, In embodiments the controller may be part of a separate unit, In embodiments the controller may be a separate computer , for example a laptop or a smart device.

In embodiments, the controller may be programmed

With a series of preset instructions or commands.

In embodiments, the controller may include readable and/or editable memory. in embodiments where the vacuum pump is a multi-stage vacuum pump, the controller may be configured to stage stages of the multi-stage vacuum pump into operation in a predetermined order.

In embodiments, the controller may be configured to receive instructions from the recorder, and/or the recorder may be configured to receive instructions from the controller.

In embodiments, the controller may be programmed to terminate the leak detection state when the

3 BE2021/5857 recorder registers that at least one of a preset time period has elapsed and/or a predetermined threshold value for pressure change is registered. Thus, the controller can be configured to leave the vacuum system from the leak detection state to a normal operating state once a pre-set period of time has elapsed or a pre-set pressure change threshold is registered by the recorder.

In embodiments, the controller may be configured so that the recorder stops recording data corresponding to the measured values in the process chamber.

Good when the logging system registers that at least sen of a preset time period has elapsed and/or a preset pressure change threshold is registered. This allows the vacuum system to pass a leak detection test and automatically enter a normal operating state, ready for normal operation.

In embodiments, the controller may be configured to override the vacuum system from the leak detection state

Return to normal operating condition, but only if the recorder determines that no leak is present or that a detected leak is not significant enough to warrant further action, for example, if a leak is detected but the leak rate can be sufficiently overcome by increasing the pump rate of the vacuum pump during normal use, the controller can transfer the Loch vacuum system from the leak detection state to a normal use state,

14 BE2021/5857

In embodiments, the controller may be programmed to prevent a transition from the leak detection mode to a normal operating condition if a sufficiently large leak, or any leak, is detected by the sensing device. is detected. For example, if a detected leak has a leak rate that is too high to be overcome by the pumping speed of the vacuum pump during normal operation, a transition from the leak detection state to the normal gas operation state can be prevented. Therefore, the normal use of the vacuum system can be automatically disabled when the recorder deems a detected lex too significant to resume normal use of the vacuum pump, A user may be alerted to the presence of a leak, or a leak of significant magnitude, so that further action is taken before the vaculum system returns to normal operation. normal use,

In embodiments, the controller may be programmed to turn OFF the vacuum system after the leak detection condition has ended,

In embodiments, the vacuum system may further include a valve located between the process chamber and the vacuum pump. The tilt may be configured to selectively isolate the process chamber. The tilt may be operable by the controller. In embodiments, the controller is programmed to close the valve to isolate the process chamber in the leak detection mode. In embodiments, the valve may be configured to leak no more than about 10 mbar per minute.

15 BE2021/5857

In embodiments, an aforesaid pressure sensor may be located on the process chamber side of the valve,

In embodiments, operation of the valve by the controller may be automated, for example, as soon as the recorder registers that the process chamber has been evacuated (in which case the valve is closed to isolate the process chamber). In other words, the operation of the valve may not be through a separate user-initiated action,

In embodiments, the controller may be programmed to start the leak detection cycle.

In embodiments, the controller may be programmed to operate the vacuum pump to evacuate the process chamber and, in the leak detection state, isolate the process chamber once the process chamber has been evacuated. Thus, a user need not manually operate the vacuum pump to evacuate the process chamber or manually isolate the process chamber in the leak detection state. Thus, in the present invention, the controller can be programmed to initiate each of the steps of a leak detection test, so that no user-initiated actions are required in between. Thus, the vacuum system may be configured to effectively perform a program of steps to generate and record data corresponding to the pressure of the process chamber over a period of time,

In embodiments, the controller may be programmed with a test schedule for activating the leak detection condition. For example, leak detection tests can be automatically performed periodically without having to perform each test manually

16 BE2021/5857 must be activated by a user. For example, the controller may be programmed with instructions to start a leak detection test on a weekly or monthly basis. In embodiments, the recorder may be programmed with a test schedule for activating the leak detection key, and the recorder configured to operate the controller,

In embodiments, the recorder may be configured to calculate one or more properties of a detected leak from two or more iterations of the leak detection condition. In other words, the recorder may be configured to calculate whether a leak worsens or stabilizes over a period of time

Longer period by plotting and comparing the results of different leak detection tests. For example, the recorder may be configured to not inform a user that a leak is increasing by so many liters per hour per month.

In embodiments, the recorder may be configured to indicate the estimated energy and/or financial cost of a detected leak. For example, the recorder may be configured to calculate and indicate that a detected leak is likely to cost an average of 100kWh more energy per month,

In embodiments, the vacuum system may be configured to enter the leak detection state only when the vacuum pump evacuates the process chamber within a preset maximum time period. In other words, when the vaculim pump

7 BE2021/5857 process chamber cannot evacuate within a predetermined time limit, the leak detection condition is not activated,

Thus, if there is a leak large enough to overcome the speed of the vacuum pump Le, the vacuum pump is prevented from endlessly trying to evacuate the process chamber. 9 Advantageously, therefore, the leak detection mode 9 is not activated if the process chamber cannot be reliably evacuated within a preset maximum time period,

In embodiments, the vacuum system may be configured to enter the leak detect state only when the vacuum pump reaches one or more minimum operating conditions.

In other words, the vacuum system is configured so that it does not enter the leak detection state when one or more minimum operating conditions are not met,

In embodiments, the one or more minimum operating conditions may include a minimum speed and/or temperature of the vacuum pump. For example, the vacuum pump may operate most effectively in the leak detection state if the vacuum pump is fully or partially {e.g. the lubricating fluids) has first been warmed up to a minimum operating temperature. As a result, the risk of damage to the vacuum pump or any other part of the vacuum system is reduced to a minimum. In embodiments, the valve is configured to open and allow fluid communication between the vacuum pump and the process chamber only when one or more minimum operating conditions are met. In other words, in embodiments, the vacuum pump is operated at

18 BE2021/5857 to meet one or more minimum operating conditions while the valve is closed.

In embodiments, the vacuum system may include one or more additional sensors to monitor the condition of the vacuum pump or other parts of the vacuum system. For example, the vacuum system may include one or more sensors for monitoring the temperature, motor current, and/or electrical supply to the vacuum pump.

Accordingly, if abnormal conditions are detected, the operation of the vacuum pump may be controlled or disabled. In embodiments, the vaculim pump may be idling in the leak detection mode. In embodiments, the vacuum pump may be substantially stopped in the leak detection mode. Consequently, the pressure in the process chamber can be monitored once the vacuum pump has safely returned to a static speed or stopped. In embodiments, the speed of the vacuum pump is not reduced until the process chamber has been isolated after evacuation of the process chamber.

In embodiments, the vaculum system may further include a user interface. In embodiments, the user interface may be configured to input information into the recorder and/or controller,

In embodiments, the information may include one or more of the following: properties of the process chamber, such as the volume of the process chamber; and/or the pressure to be produced in the process chamber when the process chamber is evacuated; and/or the preset time period to elapse; and/or the second pressure corresponding to a preset pressure change threshold. The information can thus be predetermined and programmed into the vacuum system before a leak detection test.

In embodiments, the user interface may be configured to display information to a user. In embodiments, the information displayed by the user interface may correspond to the data recorded and/or calculated by the recorder. in embodiments, the user interface may be configured to visually and/or audibly display information to a user,

Thus, the user interface allows a user to enter or receive information from the vacuum system, in embodiments the controller may include the user interface. In embodiments, the recording device! whether the controller is programmable via the user interface with a test schedule.

In embodiments, the recorder may be configured to send recorded or calculated data to a separate receiver, for example a separate computer or database Le.

In a further aspect, the present invention provides a computer-readable medium det instructions oval which, when executed by a computer, provides the described system,

in a further aspect the invention provides a method for determining the extent of a leak in a vacuum system, comprising the steps of: {1} providing a vacuum system according to one of the foregoing aspects and/or embodiments; {ii} evacuating the process chamber from the vacuum system using the vacuum pump: and (iii) subsequently activating a leak detection state of the vacuum system including: (a) icing the evacuated process chamber; and Db} recording data corresponding to the pressure of the process chamber,

The step of recording data corresponding to the pressure of the process chamber is performed by the recording device of the vacuum system,

In the method of the present invention, data corresponding to the pressure of the process chamber is automatically recorded by the recorder of the vaculum system. Also, the vacuum pump of the vaculum system is configured to evacuate the process chamber not only during a leak detection condition of the vacuum system, but also during normal operation of the vaculum system.

In embodiments, the method may include the further step of calculating a leak rate of the process chamber of the vacuum system. This step can be performed by the vaculum system recorder.

In embodiments, the method may include the further step of recording when at least one of the preset time periods has elapsed and/or a preset pressure change threshold is recorded.

21 BE2021/5857

In embodiments, the step of recording data corresponding to the pressure of the process chamber may be stopped automatically when at least one of a preset time period has elapsed and/or a preset pressure change threshold is being registered, only stop recording data when a preset

Time period has elapsed. In embodiments, the step of recording data can only stop when a preset pressure change threshold has been reached.

In embodiments, the method may include the further step of automatically terminating the leak detection state when at least one of a preset time period has elapsed and/or a preset pressure change threshold value is detected.

The invention therefore provides a method whereby a leak detection test of a vacuum system is automatically stopped once either a preset time period has elapsed and/or a preset pressure change threshold has been reached. As a result, detecting a leak in a vacuum system can be automated. A user does not have to manually monitor the pressure in the process chamber or the elapsed time, or record the corresponding data or manually stop the leak detection. The vacuum system can be automatically switched from the leak detection state to normal operation once a leak detection test has been completed.

2 BE2021/5857

In embodiments, the step of isolating the process chamber may only be performed as the preceding one

Step of evacuating the process chamber is completed within a pre-set maximum time period, i.e. if the vacuum system is unable to evacuate the process chamber, for example due to a large leak (i.e. a leak that cannot be overcome by the pumping speed of the vacuum pump}, this step is not executed indefinitely.

In embodiments, the vacuum system may include a controller and one or both of the steps of evacuating the process chamber and isolating the process chamber may be initialized by the controller of the vacuum system. Accordingly, a user need not perform either or both of these steps manually. and the automation of the process is improved. in embodiments, the method may include the further step of entering information into the vacuum system,

In embodiments, the vacuum system may include a user interface configured to facilitate the entry of information into the vacuum system,

In embodiments, the further step of entering information into the vaculum system may be performed prior to the step of activating the leak detection mode. In embodiments, the information may be information corresponding to one or more of the following: the volume of the process chamber; the pressure to be produced in the process chamber when the process chamber is evacuated; the preset

Period of time to expire; and/or a pressure die

23 BE2021/5857 corresponds to a preset pressure change threshold.

In embodiments, the method may further include the step of repeating the step of not activating a leak detection condition according to a predetermined schedule.

As a result, a leak detection test of the vacuum system can be performed automatically on a regular basis so that a user does not have to manually activate a leak detection test. Repeating a leak detection test on a predetermined schedule can also alert a user to the potential aggravation of a detected leak.

In embodiments, the method may further include the step of activating the vacuum pump to reach one or more minimum operating conditions prior to the step of activating the leak detection state.

In embodiments, the one or more minimum operating conditions may include a minimum speed and/or temperature of the vacuum pump. For example, the vacuum pump may operate most effectively in the leak detection mode if all or part of the vacuum pump (e.g., the lubricating fluids) is first heated to a minimum operating temperature. has warmed up. As a result, the risk of damage to the vacuum pump or any other part of the vaculum system is reduced to a minimum. In embodiments, the method may include isolating the process chamber prior to activating the vaculum pump to achieve one or more minimum operating conditions,

In embodiments, the method may include the further step of providing a fluid-line connection between the process chamber and the vacuum pump once the vacuum pump has reached one or more minimum operating conditions,

In embodiments, the vacuum system may include a valve positioned between the vacuum pump and the process chamber, wherein the valve may be configured to selectively isolate the process chamber. In embodiments, the valve may be operable by the vacuum system controller. in embodiments, the method may include the further step of bringing the vacuum pump to idle speed after the process chamber has been isolated. In embodiments, the method may also include the further step of substantially stopping the speed of the vacuum pump after the process chamber has been isolated. isciated.

In embodiments, the method may include the further step of displaying the data recorded by the recorder through a user interface of the vacuum system. In embodiments, the method may include the further step of displaying the calculated leak rate through a user interface of the vacuum system.

In embodiments, the method may include the further step of stopping the leak detection condition only if the vacuum system sensing system determines that no leak is present or that a detected leak is not significant enough to warrant further action.

To undertake, If, for example, a leak becomes

25 BE2021/5857 detected but the leakage rate can be sufficiently overcome by the pumping speed of the vacuum pump in the normal operating state, the vacuum system can be transferred from the leak detection state to a normal operating state. Conversely, if a sufficiently large leak or any leak is detected, the step of stopping the leak detection state may not be performed. Consequently, the vaculature system may be prevented from returning to the normal operating state. A user can therefore be alerted to the presence of a leak, or a leak of significant magnitude, so that further action is taken before returning the vacuum system to its normal operating condition.

In embodiments, the method may include the step of turning OFF the vacuum system after the leak detection condition has ended. In embodiments, the step of recording data corresponding to the pressure of the process chamber may be performed by a computer. In embodiments, one or more of the following steps may be performed by a computer: activating the leak detection mode; stopping the leak detection state; activating the vacuum system to meet one or more minimum operating conditions; operating the valve of the vacuum system; or entering information into the vacuum system,

In a further aspect, the present invention provides a computer-executable medium containing instructions that, when executed by a computer, provide the described method.

Short description of figures

Preferred Features of the present invention will now be described, by way of example, with reference to the accompanying drawings in which: ; Figure 1 shows a flowchart of steps performed during a leak detection condition of a vacuum system.

Figure 2 shows a graph plotting a series of examples of leak detection results,

Detailed description

Figure 1 depicts a flowchart illustrating the operation of a vacuum system of the present invention,

The vacuum system falls over: a process chamber, i.e. a chamber in which a vacuum process usually takes place during normal use; a vacuum pump (for example, a screw vacuum pump}; and at least one pressure sensor for monitoring the pressure of the process chamber.

The vacuum system has a leak detection condition and a normal operating condition, The vacuum pump of the vacuum system is configured to evacuate the process chamber of the vacuum system both before the leak detection condition and during the normal operating condition, In other words, no special secondary leak detection or auxiliary pump is required to evacuate the process chamber prior to the leak detection condition,

In the leak detection condition, discussed in more detail below, the evacuated process chamber is isolated from the vacuum system and the vacuum system recorder then records the pressure

27 BE2021/5857 measured by the or each pressure sensor over time to determine if there is a leak in the process chamber. If there is a leak, gas will enter the process chamber through the {or oak} leak and consequently the pressure in the process chamber will increase over time. Conversely, if there is no leak, the pressure within the process chamber will remain essentially constant over time,

The detection and recording of pressure changes within the pressure chamber over time can therefore indicate whether or not there is a leak, whether a pressure change is due to outgassing within the pressure chamber, or whether a pressure change is due to a combination of a

Jek and outgassing within the process chamber.

The recording and calculation are performed by the vacuum system recorder programmed here. The recording of data corresponding to the pressure within the process chamber over time is thus done automatically. In other words, no user actions are required to monitor and record the pressure in the process chamber over time.

Referring still to Figure 1, when starting up the vacuum system 1, a decision 2 is made

If so, then a pre-purge phase 3 must be carried out. in the prepurge phase 3 the vacuum pump is started in order to achieve one or more minimum operating conditions of the vacuum pump. For example, the vacuum pump can operate most effectively at a minimum operating temperature or speed.

For example, the pre-purge phase is performed when the temperature of the vacuum system including the vacuum pump, or part thereof, is 5°C or lower. In another example, the pre-rinse phase is carried out if the process to be carried out under vacuum contains a significant amount of water vapour,

If a decision 2 is made not to activate the pre-purge stage 3, the vacuum system immediately moves to the vacuum control stage 5, described below,

The decision Z whether or not to go to the pre-preliminary stage 3 can be made autonomously by the recorder.

The vacuum system includes a valve configured to isolate the process chamber, as well as to substantially provide fluid communication between the vacuum pump and the process chamber.

Prevent,

In the prepurge stage 3, the valve is closed to isolate the process chamber, The valve opens when one or more minimum operating conditions 4 are met and the vacuum system moves to the vacuum control stage 5,

Conversely, if a minimum operating condition 4 is not met, the vaculum system will not enter the vaculum control phase 5, A user may be alerted 12 to the result of the pre-purge phase 3, in particular if a minimum operating condition 4 is not met, In the vacuum control stage 5 the vacuum pump is activated to evacuate the process chamber. Depending on the use of the vacuum system, a full or partial vacuum can be produced in the process chamber. In this example, the vacuum pump is configured to produce a rough vacuum, i.e. a pressure of 0.1 to 1000 mbar, in the process chamber. The vacuum pump runs at a maximum permitted speed during the vacuum control phase

23 BE2021/5857 to evacuate the process chamber as quickly as possible. However, the maximum permissible speed depends on the type of vacuum pump and the operating conditions of the vacuum pump.

The vacuum system includes a number of sensors configured to sense one or more of the vacuum pump temperature, motor current and/or the power supply to the vacuum pump Le. Consequently, if an abnormal value is measured, the maximum speed of the vacuum pump may be reduced , or the vacuum pump can be turned off until the problem is solved.

The vacuum adjustment stage 5 is activated for a preset maximum time, so that in the event of a large leak in the process chamber, the vacuum pump does not endlessly try to evacuate the process chamber. Manual intervention is therefore not necessary if the vacuum pump fails to

Evacuate process room Le,

For example, if a valve is accidentally left open, the vacuum pump will probably not overcome the resulting leak and thus the process chamber will not be evacuated within the pre-set period. 13 are made: so that appropriate action can be taken to resolve the problem, if the process chamber is evacuated within the set maximum time during the vacuum control phase & a decision 7 is made whether the vacuum system should go into leak detection state 10, or whether the vacuum system must proceed to a normal operating condition B, The decision 7 whether or not to transfer

30 BE2021/5857 from the leak detection state 10 can be taken autonomously by the recorder according to a test schedule, for example.

If a decision is made to proceed to normal operating mode 8, no leak detection test is performed and the vacuum pump continues to evacuate the process chamber # for a normal operating process. During the vacuum control phase { 5 the valve is open so that the vacuum pump can evacuate the process chamber. If a decision 7 is made to proceed to a normal operating condition 8, the valve remains open so that evacuation of the chamber can continue.

Any process or use of the vacuum system that is not primarily aimed at detecting a leak in the process chamber, for example, can be performed in normal operating mode 8 .

In the Leak Detection state 10, when activated, the valve is first closed so that the evacuated process chamber is isolated from the vacuum pump and from the outside of the process chamber.

The vacuum pump then enters a stop phase, in which the vacuum pump slows down to a stationary speed or necessarily comes to a stop. Simultaneously with or after the shutdown phase of the vacuum pump, the or each pressure sensor measures the pressure within the process chamber. The vacuum system recorder records data corresponding to the pressure measured within the process chamber, including the pressure reached when the process chamber was evacuated and the time elapsed since the start of the leak detection state 10, i.e. since the process chamber was

Isolated.

31 BE2021/5857

The logging data set is programmed to record the data corresponding to the pressure measured in the process chamber in the lcop of time and, based on that recorded data, calculate one or more characteristics of a detected leak, if any. The properties of a leak may include the presence, size and/or location of the detected leak,

The recording set is programmed to register when the first of a preset period has passed and a preset pressure change threshold within the process chamber has been reached. The preset time period and the preset pressure change threshold are pre-programmed into the logging set.

For example, the process chamber is evacuated to produce a first pressure {P1} in the vacuum control stage 5 and the preset pressure change threshold corresponds to a second pressure (P2} which is greater (i.e. a higher pressure) than the first pressure (P1} If, when the leak detection state 10 is activated and the process chamber is iscised, the pressure in the process chamber rises from the first pressure to the second pressure within the preset elapsed time period, the recorder registers this event and may just determine that there is a leak. is present.

In addition, the recorder is programmed to stop recording data when the first of these parameters is reached. The preset pressure change threshold may not be reached by the time the preset time period is reached.

32 BE2021/5857 has expired, or that the preset pressure change threshold is reached before the preset time period has elapsed. In both cases ; nevertheless, the recorder stops recording data and the leak detection state 10 is terminated.

The recorder is programmed to calculate a pressure rise rate based on the recorded pressure change within the process chamber over time, The recorder is also programmed to calculate a Process Chamber Leak Rate cp based on the volume of the process chamber and the recorded # data ,

The vacuum system includes a controller that is programmed : to stop the leak detection mode when the { 15 recorder registers that at least one of sen { predetermined time periods has elapsed and/or a pre-set pressure change threshold is registered, i.e. The recorder is configured to transfer the vaculum system out of the leak detection state.

For example, if the preset time period has elapsed and no leak has been detected, or a leak small enough to be sufficiently overcome by the vacuum pump in normal operation has been detected, the controller will return the vacuum system from leak detection condition 10 to normal operation condition 8 from the flow chart of Figure 1. Alternatively, the vacuum system can be turned off automatically after the end of the leak detection state 10,

33 BE2021/5857

For example, if there is a leak and the preset pressure change threshold is reached (or if a significant leak is recorded after the preset time period has elapsed), one or more properties of the leak are calculated by the logging set and can be used for sen user 14 are displayed. The vacuum system can then go into normal operating mode 8, or can be turned OFF.

Thus, regardless of whether or not sen li is detected during the leak detection state 10, the vaculum system may be configured to return to a normal operating condition afterwards,

The results of each iteration of the leak detection condition 10 are stored in a memory of the vacuum system so that the results of each iteration of the leak detection condition 10 are compared,

The controller is also programmed with a schedule that dictates when to activate the leak detection mode 10 so that a user does not have to manually activate the leak detection mode 10 . The controller is also programmed with instructions whether or not prepurge stage 3 is required before leak detection mode 10. Decisions 2, 4, 6, 7, il of the flow chart of

Figure 1 can thus be taken by the controller pre-programmed to make those decisions.

In Figure 2, the results of leak detection tests, i.e., several iterations of the leak detection mode 10, are plotted over time so that a user can be aware of the magnitude of the process chamber's leak.

34 BE2021/5857

The vacuum system includes a user interface for entering information into the recording set and/or controller and for displaying information to a user. The information displayed to the user may include: a detected leak rate, optionally calculated as described above; whether or not there is a leak, as predetermined in the vacuum system; and/or the characteristics (e.g. its deterioration or improvement) of a detected leak over time / after several iterations of the leak detection test.

The user interface allows a user to enter information that matches! with one or more properties of the process chamber and/or the vacuum pump, so that calculations performed by the recorder are aligned with the hardware of the vaculim system. For example, the volume (V) of the process chamber and the pressure to be produced in the process chamber when the process chamber is evacuated can be entered so that the boom rate can be calculated by the recorder,

In another example, the preset pressure change threshold and preset time period to elapse are entered so that the recorder is configured to stop recording and/or stop the leak detection condition when the first of these parameters is met.

Legend 1 Launch

Z Pre-rinse decision 3 Pre-rinse phase

35 BE2021/5857 4 Minimum operating condition decision

Vacuum Control Phase & Evacuation Decision 7 Leak Detection Decision 9 5 8 Normal Operating Condition 3 Off

Leak detection condition 11 Leak detected decision iz Minimum operating condition warning 19 13 Evacuation warning : 14 Leak detection warning

Claims (1)

Conclusions Li. A vacuum system with a leak detection condition, which vacuum system includes: a process chamber with a Le evacuate [loud volume; a vacuum pump configured to evacuate the process chamber; at least one pressure sensor configured to measure the pressure within the process chamber; and a recorder programmed to record the pressure measured in the process chamber; wherein, in a leak detection condition, the evacuated process chamber is isolated and the recorder is programmed to record data corresponding to the pressure measured within the evacuated process chamber in lcop of time; and wherein the vacuum pump is configured to evacuate the process chamber prior to the leak detection condition and during normal use of the vacuum system. The vacuum system of claim 1, wherein the recorder is programmed to calculate a leak rate of the process chamber, The vacuum system of claim 1 or 2, wherein the recorder is programmed to record when at least one of a preset time period has elapsed and/or a preset pressure change threshold value is recorded, a. The vacuum system of claim 3, the vacuum system further comprising a controller; wherein the controller is programmed to terminate the leak detection condition when the recorder registers that S at least sen of a preset time period has elapsed and/or a preset pressure change threshold is registered. The vacuum system of any of the preceding claims, comprising a valve disposed between the process chamber and the vaculum pump and configured to selectively isolate the process chamber; the valve being operable to close in the leak detection state, The vacuum pump of any one of the preceding claims, wherein the vaculim system is configured to enter the leak detection mode only when the vacuum pumps reach one or more minimum operating conditions. The vacuum system of any one of the preceding claims, wherein the vacuum system is configured to enter the leak detection mode only when the vacuum pump evacuates the process chamber within a preset maximum time period. 8. The vacuum system of any one of the preceding claims, wherein the vacuum pump is idling or substantially stationary in the leak detection mode, 9. A method for determining the receipt of a leak in a vacuum system comprising the steps of: i. providing a vacuum system according to any one of claims 1 to 8; ii, evacuating the process chamber from the vacuum system using the vacuum pump; and iii. subsequently activating a leak detection condition of the vacuum system including: ; & a. isolating the evacuated process chamber; and LL. recording data that corresponds to the pressure in the process chamber. The method of claim 3, comprising the further step of calculating a leak rate of the process chamber of the vacuum system. The method of claim 9 or 10, comprising the further step of recording when at least one of a preset time period has elapsed and/or a pre-set pressure change threshold value is registered, The method of any one of claims S to 11, comprising the further additional step of automatically terminating the leak detection mode when at least one of a preset time period has elapsed and/or a preset pressure change threshold is registered. The method of any one of claims 9 to 12, wherein the step of isolating the process chamber is performed only if the vacuum pump reaches one or more minimum operating conditions, The method of any one of claims 5 to 13, wherein the step of isolating the process chamber is performed only if the previous step of evacuating the process chamber is completed within a predetermined maximum time period. A computer readable medium containing instructions which, when executed by a computer, provide the system of any of claims 1 to 8 and/or perform the method of any of claims 9 to 14.