HK1262019A1 - Device and method for determining the size of a leaking hole - Google Patents

Description

Technical field

The present invention relates to a test device for a sample and to a process implemented by this device.

Such a device allows a user to test a sample and measure the integrity of the sample envelope.

State of the art

There are systems for testing samples, for example to measure the level of a given gas inside the sample or to measure a leakage or a leakage problem in the sample.

A recurring problem with state-of-the-art solutions is that they are too expensive, too long (typical response time of a dozen seconds for an infrared measurement of CO2 levels), or not accurate enough (minimum size of a measurable leakage hole of 5 μm with a relative overpressure of 500 mbar, or with a helium scan in the chamber to be measured).

US 2008 / 009 26 35 describes an instrument for detecting leaks, using Poiseuille's law.

US 5 369 984 describes an apparatus for determining the size of a leakage hole by a pressure differential method

The purpose of the present invention is to propose a device and test method for a sample having at least one of the following technical advantages: The results of the survey were: low production cost compared to the state of the art,high speed of measurement compared to the state of the art, andhigh measurement resolution compared to the state of the art.

Explanation of the invention

This objective shall be achieved with a gas flow test device comprising: an orifice,means of generating a gas flow into the device along at least one flow path through the orifice,at least one pressure sensor,each pressure sensor being arranged to measure a gas flow pressure along at least one flow path,and a mass flow meter,arranged to measure a representative parameter of the mass flow rate of the gas flow along each flow path,and where at least one flow path includes an exhaust path ending in the orifice,means of generating the gas flow are arranged to exhaust a leakage gas into the sample along the exhaust path,at least one pressure sensor includes an exhaust pressure sensor arranged to measure a pressure of the exhaust gas along the exhaust path,the mass flow meter is arranged to measure a parameter representative of the mass flow rate of the exhaust gas along the exhaust path,and where the device is characterised by the fact that it also includes computing means arranged to determine the size of a leakage hole, from a measurement of a parameter representative of the mass flow rate along the exhaust path, the mass flow meter being a mass flow rate meter with thermal conductivity.

The exhaust pressure sensor shall preferably be located along the exhaust path between the flowmeter and the orifice.

The calculation means can be arranged to determine the size of the leakage hole in the form of a calculation which depends in an affine manner on the square root of the mass flow representative parameter along the exhaust path.

The means of calculation can be arranged to determine the size of the leakage hole further from a pressure measurement along the exhaust path by the exhaust pressure sensor. The means of calculation can be arranged to determine the size of the leakage hole in the form of a calculation that is affine to the inverse of the fourth root of the pressure measurement along the exhaust path. The means of calculation can be arranged to determine the size of the leakage hole according to the formula where Dm is the representative mass flow rate parameter, Pr is the pressure measured by the exhaust pressure sensor, and a and b are the numerical calibration coefficients.

The means of calculation may be arranged to trigger a determination of the size of the leakage hole for a pressure value along the exhaust path measured by the exhaust pressure sensor corresponding to an exhaust pressure reference value, the means of calculation being arranged to determine the size of the leakage hole from a value of the parameter representative of the mass flow rate along the exhaust path measured simultaneously to the pressure measurement measuring the pressure value corresponding to the exhaust pressure reference value. The means of calculation may be arranged to determine the size of the leakage hole according to the formula where Dm is the representative mass flow rate parameter and a and b are the numerical calibration coefficients.

At least one flow path may include a calibration path through the orifice, and within the device, the calibration path may narrow locally at a measuring hole, the means of calculation being preferably arranged for: Determine the measuring hole size from a measurement of the mass flow representative parameter along the calibration path, and adjust calibration coefficients for calculating a leakage hole size if the measuring hole size determination does not correspond to an actual measuring hole size stored by the computing means.

The device according to the invention may include a valve arranged to complete the exhaust path by a short circuit path through the office and the flow generating means but not through the flow meter, the valve being preferably arranged to adjust the total flow through the exhaust path and the short circuit path.

The invention also proposes a gas flow test method for a sample comprising: an exhaust gas expiration in the sample flowing along an exhaust path terminating in a hole connected to a sample,a measurement of the exhaust gas pressure along the exhaust path,a measurement of a parameter representative of the mass flow rate of the exhaust gas along the exhaust path, and the process being characterised by:a determination of the size of a leakage hole in the sample, from the measurement of the parameter representative of the mass flow rate along the exhaust path, the measurement of a parameter representative of the mass flow rate being a mass flow rate measurement by a mass flow rate thermal conductivity meter.

The pressure measurement may be carried out by an exhaust pressure sensor located along the exhaust path between the flowmeter and the sample.

The determination of the leakage hole size may include a calculation of the leakage hole size which is affine to the square root of the mass flow representative parameter along the exhaust path.

The determination of the size of the leakage hole can be further carried out from the pressure measured along the exhaust path. The determination of the size of the leakage hole may include a calculation of the size of the leakage hole which is affine to the inverse of the fourth root of the pressure measurement along the exhaust path. The determination of the size of the leakage hole may include a calculation of the size of the leakage hole according to the formula where Dm is the representative mass flow rate, Pr is the measured pressure, and a and b are the numerical calibration coefficients.

The determination of the leakage hole size may be triggered for a pressure value along the measured exhaust path corresponding to a pressure reference value, the determination of the leakage hole size being made from a value of the mass flow parameter along the exhaust path measured simultaneously to the pressure measurement measuring the pressure value corresponding to the pressure reference value. where Dm is the representative mass flow rate parameter and a and b are the numerical calibration coefficients.

At least one flow path may include a calibration path through the orifice and narrowing locally at a measuring hole, and the process according to the invention may include: a calibration gas flow along the calibration path,a calibration gas pressure measurement along the calibration path,a measurement of a parameter representative of the mass flow rate of the gas calibration gas along the calibration path,a determination of the size of the measuring hole from a measurement of the mass flow rate representative parameter,and an adjustment of numerical coefficients for calculating a leakage hole size if the determination of the measuring hole size does not correspond to an actual measuring hole size stored by means of calculation.

The process of the invention may involve adjustment, by a valve arranged to complete the exhaust path by a short circuit path through the office and the flow generating means but not through the flow meter, of the total flow through the exhaust path and the short circuit path.

Description of figures and methods of execution

Further advantages and features of the invention will be apparent from the detailed description of the not-so-limitative implementations and embodiments and the following attached drawings: Figure 1 is a schematic profile cut-off view of a device implementing a process outside the scope of the invention, and showing a gas flow when the device is in the suction gas analysis position or in the calibration position,Figure 2 schematically shows the pneumatic circuit of the device in Figure 1 in the suction gas analysis position or in the calibration position,Figure 3 is a schematic cut-off view from below a part of the device in Figure 1 and showing a gas flow when the device is in the suction gas analysis position or in the calibration position,Figure 4 is a schematic cut-off view of the pneumatic circuit of the device in Figure 1 in a dilution position or in another calibration position,Figure 5 is a schematic cut-off view of the device in Figure 1 using a process according to the invention and showing a gas flow when the device is in an exhaust leak detection position,Figure 6 shows the pneumatic circuit of the device in Figure 1 in the exhaust leak detection position,Figure 7 shows the pneumatic circuit of the device in Figure 1 in the exhaust rapid inflation position,Figure 8 shows the pneumatic circuit of the device in Figure 1 in the exhaust burst position.

The first example of a device 1 outside the scope of the invention is described in Figures 1 to 8.

The test shall be carried out on a gas flow test tube.

The device 1 shall include a hole 2. This hole 2 is the hole in the hollow of a hollow needle, arranged in the centre of a 24 gauge airtight suction cup designed to be plated against a sample 13 (such as a food bag or any container with at least one flexible surface of compatible size which can be passed through by a needle). The suction cup avoids the use of sealing septa to perform a test without contamination of the air outside the container.

The device 1 shall also include means 3 to generate a gas flow 25 (gas to be analysed, dilution gas, leakage gas, calibration gas) into the device 1 along at least one flow path through the orifice 2, through a mass flow meter 4, and through a valve 8 called the selection valve.

Valve 8 is a valve with more than two passages (inlet or outlet), with several possible positions. Each valve 8 position corresponds to a specific configuration of opening for the passage of gas flow 25 or closing to prevent such passage between some of the inlet and outlet passages of valve 8.

The valve 8 is preferably a proportional valve (preferably drawer valve).

The valve 8 is for example a valve made from a Mecalectro brand electromagnet or a Parker valve.

The orifice 2 and valve 8 are common to all the flow paths, and a micro-porous filtration element 23 is preferably located along this common part of the flow paths.

For example, filter 23 is a PTFE filter from Millipore or Sartorius.

Generation 3 means include a turbine, or more generally a reversible flow generator at controlled speed to be enslaved in flow or pressure, e.g. Papst brand.

The means of generation 3 are reversible, i.e. they are arranged to generate both a gas flow 25 at intake and at expiration (i.e. in a flow direction opposite to the intake).

A valve 16 and orifice 2 delimit the two ends of each flow path.

Valve 16 is a valve with more than two paths (in or out), with several possible positions. Depending on the position of valve 16, valve 16 connects the generation means 3 to the outer atmosphere of device 1 in a first position 17 or to a reference gas source 19 in a second position 18.

The device 1 comprises at least one pressure sensor 5, 6, each pressure sensor 5, 6 being arranged to measure a pressure Pr of the gas flow 25 along at least one of the flow paths. More precisely, the pressure Pr measured by each sensor 5 or 6 is a relative pressure (respectively depression or overpressure) generated by the flow 25 (respectively sucked into device 1 or exhaled from device 1) relative to the absolute pressure that would be measured in the absence of this flow 25.

The mass flow meter 4 is arranged to measure a representative parameter of the mass flow rate of the gas flow along each flow path. This parameter is typically an electrical intensity or voltage, and is preferably proportional to the mass flow rate of the gas flow 25 or connected to the mass flow rate of the gas flow 25 by a programmed and/or stored calculation within the device's computing means 7. All sensory and servo elements 5, 8, 6, 20, 4, 3, 16 are connected to the computing means 7 by an electrical and/or data transfer or control link (links shown in dots in Figure 2). The computing and control means 7 are only schematically represented in Figure 2 so as not to overload the other figures.

In this document, the word each is used to refer to any unit (e.g. sensor or flow path) taken individually in a set. In the case where that set includes at least one unit (i.e. e.g. at least one sensor or at least one flow path ), there is therefore a limit case where the set includes only one unit (e.g. e.g. one sensor or one flow path) and where the word each refers to that unit only.

Computing devices 7 include only electronic and/or software technical means (preferably electronic), and include a computer central unit, and/or a processor, and/or a dedicated analogue or digital circuit, and/or software.

The mass flow meter 4 is a mass flow meter with thermal conductivity.

Typically, the mass flow meter 4 consists of a heating element (heat source) and two temperature probes. The heating element is located between the two temperature probes so that the heating element and the two temperature probes are all three aligned along the direction of flow of the gas flow 25 at the mass flow meter level. The mass flow meter 4, depending on the change in temperature or amount of heat between the two temperature probes bordering the heat source, is arranged to determine the representative parameter of the mass flow rate of the gas flow 25 through the flow meter 4 (i.e. a mass of gas passing through the flow path for a period of time).

The advantage of a mass flow meter, especially in terms of thermal conductivity, is that it has a very fast response time, which will allow access to a leakage hole diameter 22 or to quantify the presence of a gas of interest with a very high measurement speed (typical response time of 3 milliseconds).

At least one flow path includes: an aspiration path starting from orifice 2 (i.e. the gas flow enters the aspiration path through orifice 2), an exhaust path ending at orifice 2 (i.e. the gas flow leaves the exhaust path through orifice 2), and a dilution path ending at orifice 2 (i.e. the gas flow leaves the dilution path through orifice 2).

All such flow paths are permitted in device 1 according to valve 8 position and flow direction 25 generated by generation means 3. The position of valve 8 and flow direction 25 generated by generation means 3 (exhaust or suction) at a given time determines the only (zero or one among the suction path, exhaust path or dilution path) flow path through which gas flow 25 flows at that time in device 1.

All the drains are closed

For a first valve 8 position 9, valve 8 is closed and the gas flow 25 generated by means 3 shall not flow along any flow path as defined above.

The path of aspiration

With reference to Figures 1 to 3, for a second position 10 of valve 8 and for generation 3 means sucking gas flow 25, means 3 to generate gas flow 25 are arranged to suck up a gas to be analysed from a sample 13 so that this gas to be analysed flows into device 1 along the suction path.

The gas to be analysed includes, for example: 0 to 100% of a mixture gas comprising one or more molecules (e.g. N2 and O2), each of these molecules having with the other molecules of the mixture gas a thermal conductivity difference of not more than 10% (preferably not more than 5%) under identical temperature and pressure conditions (typically, for each pair of two mixture gas molecules having thermal conductivity Di and Dj respectively under identical temperature (flow temperature 25 when measuring pressure Pr, typically 20°C) and pressure (measuring pressure Pr), we have And what ? , see preferably And what ? ); this threshold, which is optimally set at 5 or 10%, may also be higher than 10% (20%, 30%, etc.) in other embodiments, but the higher this threshold, the less good the resolution of the device according to the invention; and0 to 100% of a gas of interest comprising only one or more molecules (e.g. NO2 and/or CO2) with a difference in thermal conductivity between them of less than or equal to 10% (preferably less than or equal to 5%) for identical temperature and pressure conditions (typically, for each pair of two molecules of the gas of interest having a thermal conductivity of Ci and Cj respectively for identical temperature conditions (temperature measured at 25°C, typically Pr Pr) and pressure measured at 20°C), And what ? , see preferably And what ? This threshold, which is optimally set at 5 or 10%, may also be higher than 10% (20%, 30%, etc.) in other embodiments, but the higher this threshold, the less good the resolution of the device according to the invention. Each molecule of the gas of interest has a different thermal conductivity from the thermal conductivity of each of the molecules of the mixture gas of at least 20%, preferably at least 30%, for identical temperature and pressure conditions (typically, for each molecule of the gas of interest having thermal conductivity here and for each molecule of the mixture gas flow having thermal conductivity here, for identical temperature conditions (temperature at measurement of pressure, typically 20°C) and pressure (Pr, Pr, Pr, Pr), And what ? , see preferably And what ? This difference of at least 20 or 30% is due to the accuracy of the device 1, the higher the difference, the more the gas of interest is discriminated and the use of electronic amplification is reduced; this threshold, which is optimally set at 20 or 30%, may also be less than 20% in other embodiments, but the lower this threshold, the less resolution the device will have according to the invention or the more efficient electronics will be required for discrimination, or other technical means of redundant embodiment of the device described in other measurement scales.

Within device 1, the said suction path narrows locally at a measuring hole 14. The measuring hole 14 is a hole made in a plate 15. The plate 15 is typically stainless steel. The plate 15 is removable so that it can typically be replaced either in case of wear of the hole 14 or to change size from hole 14 within the device 1. The hole 14 is of known dimension typically 5 μm to 150 μm in diameter. The flow passes through a second 21th hole of greater diameter (typically about 2 mm) at the measuring hole 14. The probe of this perforated load 15 is a fitting element of the drill bit, and is much smaller than the size of the micro-fortification hole (typically about 10 times smaller)

This hole 14 is the passage of the lowest opening area (per unit area perpendicular to the flow direction 25) for gas flow 25 in device 1 compared to the rest of the entire intake pathway, and even preferably the exhaust pathway and dilution pathway. Typically, all locations of the intake pathway (and even preferably the exhaust pathway and dilution pathway), except for hole 14 itself of course, have an opening area (per unit area perpendicular to the flow direction 25) at least 5 times larger than the opening area (per unit area perpendicular to the flow direction 25) of hole 14.

The 14th hole is circular.

At least one pressure sensor 5, 6 shall include a first pressure sensor 6 (so-called suction) arranged to measure a pressure Pr (more precisely a depression, directly related to the suction force of turbine 3) of the gas to be analysed along the suction path, preferably but not limited to 20-500 mbar or wider (between 4-500 mbar or between 4-1000 mbar or wider depending on the capacities of turbine 3).

The mass flow meter 4 is arranged to measure the representative parameter of the mass flow rate of the gas to be analysed along the suction path.

The calculation means 7 are arranged to quantify the presence of a gas of interest in the gas to be analysed (this presence is typically quantified as a percentage of the gas of interest in the gas to be analysed or in moles per litre of gas to be analysed or as a volume of gas of interest e.g. in millilitres), from a measurement of the parameter representative of the mass flow rate of the gas to be analysed.

The calculation means 7 are arranged to quantify the presence of the gas of interest in the form of a calculation of a proportion or volume of the gas of interest which depends on the diameter of the measuring hole 14. i.e. if the diameter or width of the hole 14 is changed without being indicated (by a program, a command, a setting button, etc.) in device 1, the calculation of proportion or volume of the gas of interest by device 1 becomes false.

The first suction pressure sensor 6 is located along the suction path between orifice 2 and measuring hole 14 for better measurement accuracy.

The mass flow meter 4 is located along the suction path so that the measuring hole 14 is located along the suction path between orifice 2 and the mass flow meter 4.

Experimentally, the inventors of the present invention realized that an excellent accuracy of measurement of the size of a hole (e.g. reference 14 or 22) of narrowing within a flow could be achieved by passing the gas stream 25 (typically air) through this hole and measuring the diameter of this hole φcal by means of the following formula: With Dm the representative parameter of the mass flow of this gas flow through this hole and Pr the pressure of this gas flow, and X and Y the numerical calibration coefficients.

For the measurement of Dm, the mass flow meter 4 is optimized for one or more types of gas with a default value of thermal conductivity (also called thermal conductivity).

For example, in the case of the Honeywell AWM series mass flow meter 4, the flow rate Dm measured by this flow meter 4 shall be multiplied by a factor of 1 (no correction) if the gas flow is air and/or N2 and/or O2 and/or NO and/or CO and shall be corrected by multiplying by a correction factor Kcal=1,35 if the gas flow is a flow of CO2 and/or N2O and/or NO2, or a factor Kcal=0,5 for He, Kcal=0,7 for H2, Kcal=0,95 for Ar, and Kcal=1,1 for CH4 and/or NH3, etc. (refer in general to the flow meter 4 model leaflet used).

Consider a mixture of O2 and CO2 from sample 13 and circulating in device 1 along the suction path as the gas to be analysed; suppose that we know that these two gases each make up the mixture in a proportion of 0 to 100%, but that the proportions of these two gases are unknown.

If the calculation means 7 calculates, by the first formula described above, a hole diameter of 14 φcal of 100 μm, the calculation means 7 deduces either that the O2 proposal in the mixture is 100% or that the CO2 proportion in the mixture is 0%, whichever of these gases is considered to be the gas of interest.

If the calculation means 7 calculates, by the φcal formula described above, a diameter of hole 14 of 135 μm, calculation means 7 infer either that the O2 proposal in the mixture is 0%, or that the CO2 proportion in the mixture is 100%, depending on which of these gases is considered to be the gas of interest.

In general, if the calculation means 7 calculate, by the formula of φcal described above, a diameter of the hole 14 of φcal, the calculation means deduce (by a formula hereinafter called 2nd formula ) that the proposal of CO2 in the mixture is or that the O2 motion in the mixture is according to the gas of interest considered, with Kcal the correction factor for the gas of interest as explained above (Kcal=1,35 for CO2).

The calculation means 7 do not have to go through two steps of calculating the diameter of hole 14 (first step, first formula) and then deducting the proportion of the gas of interest (second step, second formula), but can directly calculate this proportion in a single calculation combining the two steps and therefore the two formulas.

The calculation means 7 are therefore arranged to quantify the presence of the gas of interest in the form of a calculation of a proportion or volume of the gas of interest which depends preferably in an affine way on the square root of the mass flow parameter Dm.

Alternatively, in the less precise case of a limited development of the first formula to order one, the calculation means 7 are arranged to quantify the presence of the gas of interest in the form of a calculation of a proportion or volume of the gas of interest which is closely dependent on the representative mass flow parameter.

In general, in the case of a limited development of the first formula to the Z-order (with Z an integer greater than or equal to 1), the means of calculation 7 are arranged to quantify the presence of the gas of interest as a polynomial of degree Z of the mass flow representative parameter.

In this context, two variants, possibly combinable within the same device 1, are possible.

In a first variant, the calculation means 7 are arranged to quantify the presence of the gas of interest further from a pressure measurement Pr by the intake pressure sensor: preferably, the means of calculation 7 are arranged to quantify the presence of the gas of interest in the form of a calculation of a proportion or volume of the gas of interest which is affine to the inverse of the fourth root of the pressure measurement by the suction pressure sensor. For example, the means of calculation 7 can be arranged to quantify the presence of the gas of interest in the form of a calculation of a proportion or volume of the gas of interest which depends in an affine manner on the inverse of the pressure measurement by the pressure sensor 6 of the suction. with Dm the representative mass flow rate parameter measured by flow meter 4, Pr the pressure measured by suction pressure sensor 6, M and N the numerical calibration coefficients.

In a second variant, Pr the pressure measured by the suction pressure sensor 6 is not taken into account in the formula for calculating the proportion or volume of the gas of interest, but serves as a trigger ( trigger ): the means of calculation 7 are arranged to trigger a quantification of the presence of the gas of interest for a pressure value Pr measured by the suction pressure sensor 6 corresponding to the reference value of the suction pressure, the means of calculation 7 being arranged to quantify the presence of the gas of interest from a Dm value of the mass flow parameter measured simultaneously with the measure of pressure corresponding to the reference value of the suction pressure. Preferably with the formula: with Dm the mass flow rate representative parameter as measured by flowmeter 4 and A and B the numerical calibration coefficients.Optionally according to the formula: MDm + N or any other polynomial of degree Z of Dm as explained above, with Dm the mass flow rate representative parameter as measured by flowmeter 4 and M and N the numerical calibration coefficients.

All calibration factors A, B, M, N, A, M, a, b, a are memorised by means of calculation 7 and are defined in advance, typically by calibrating the device 1 with samples 13 in known proportions of different gases or with samples 13 each with a leakage hole 22 of known dimension.

The value of each calibration factor depends on the gas under consideration. e.g. a mixture gas of O2 mixed with a gas of interest of CO2 or a mixture gas of He mixed with a gas of interest of CH4+NH3 etc. can be assumed.

The device 1 therefore includes a structured interface to define the mixture gas and the gas of interest, and the calculation means 7 are structured to select the values of the calibration factors according to the defined mixture and gas of interest.

The suction path passes successively through orifice 2, filter 23, pressure sensor 5, valve 8, pressure sensor 6, measuring hole 14, gas sensor 20, passage hole 21, flow meter 4, generation means 3 and valve 16.

The device 1 shall also include at least a sensor 20 arranged to quantify the presence of a gas consisting of a given molecule whose thermal conductivity would not be discriminated by any other gas or molecule present.

The calculation means 7 (e.g. in a case where the mixture gas is O2 and the gas of interest is a mixture of CO2 + NO2) are further arranged to quantify the presence of a first molecule of interest (e.g. CO2 in this case) of the gas of interest having a certain thermal conductivity, the device 1 including for this purpose along the suction path at least one gas sensor 20 (e.g. NO2 sensor in this case, e.g. City technology brand) arranged to quantify the presence (proportion in % or in mol.l-1 or e.g. volume) of at least one other molecule of interest (e.g. NO2 in this case) which has a thermal conductivity at least 10% different from the thermal conductivity of the first molecule of interest for the temperature and conditions of the first molecule of interest (NO2) and a means of quantifying the presence of other molecules of interest (CO2) being the presence of a temperature and pressure of the first molecule of interest (NO2) and a means of quantifying the presence of the first molecule of interest (CO2) and a method of calculating the presence of the presence of the second molecule of interest (CO2) is used to quantify the presence of the presence of the first molecule of interest (NO2) and the presence of the presence of other molecules of interest (CO2) and the temperature (CO2) is subtrained from the temperature and pressure of the first molecules of interest (CO2) (CO2).

For example, if we measure: Proportion of gas of interest CO2+ NO2=20% of the gas to be analysed Proportion of NO2= 5% of the gas to be analysed

So we can conclude: Proportion of mixed gas (O2) = 100 - Proportion of CO2+NO2 = 80% of the gas to be analysedProportion of CO2= 15% of the gas to be analysed

The sensor 20 is located along the suction path so that the measuring hole 14 is located between orifice 2 and sensor 20. The sensor 20 is located in a measuring chamber along the suction path between the measuring hole 14 and a passage hole 21 wider than the measuring hole 14.

At least one sensor 20 may also be an O2 sensor, or other (e.g. an O2 sensor and NO2 sensor assembly), e.g. if the mixing gas includes a mixture of O2 and N2 in order to discriminate between these two molecules.

Dilution route

As shown in Figure 4, for the same position (second position 10) of valve 8 as the intake path, and for generation means 3 exhausting gas flow 25, means 3 to generate gas flow 25 are arranged to exhaust a dilution gas along the dilution path.

The dilution path is therefore the same as the aspiration path but the gas flow 25 is in the opposite direction.

For the dilution pathway, valve 16 is in its second position 18 connecting means 3 to the gas source 19.

The dilution pathway is used to increase the volume of the gas to be analysed in sample 13.

Dilution path: example 1

Suppose that sample 13 initially contains only a mixture of CO2 + NO2 without O2 as the starting gas, but in too small a quantity to be able to suck this mixture into the device 1 by filling the entire suction path: it is then impossible to determine the proportions of CO2 and NO2 as it is. On the other hand, if by the dilution path O2 from source 19 is inserted into sample 13 then sample 13 contains a mixture of CO2 + NO2 + O2 in a sufficient quantity to make measurements. The proportion of CO2, NO2, O2 after dilution can be determined as described above and the proportion of CO2 and NO2 before dilution can be deduced.

For example, if we measure: CO2+NO2=20% of the gas to be analysed after dilutionNO2=5% of the gas to be analysed after dilution

So we can conclude: O2=100 - CO2+NO2=80% of the gas to be analysed after dilution

It 's either: The following table shows the calculation of the CO2 emissions from the use of the fuel:

Dilution path: example 2

Suppose that sample 13 initially contains only a mixture of N2 and O2 as the initial gas, but in too small a quantity to be able to suck this mixture into the device 1 by filling the entire suction path: it is then impossible to determine the proportions or volumes of O2 and N2 as they are.and O2 after dilution as described above using the volume of gas injected and the volume of gas inhaled. Initial stage: The volume of gas assumed to be contained is V1 (typically this problem is encountered for containers with a available volume of less than 3 ml). This volume V1 is unknown at the initial stage. The volume V1 contains mostly N2 and traces of O2 which are not measurable due to the volume of gas available in the container.Dilution: the volume is diluted with 100% CO2 by injection of a volume V2 = 10 ml at least sufficient to excite the O2 sensor (note 20).The V2 volume is then re-sucked.

The proportions given are: O2+CO2+N2 = 1.34 instead of 1.35 (reference N2+O2, air)The amount of N2+O2 present in the diluted mixture is = (100-1.34x100/1.35) xV2 = 0.00296 x V2=0.0296mlThe volume of CO2 in V2 is V2-0.037%xV2 = 9.97mlThe CO2 concentration in V2 has become 99.704%The proportion of O2 in the diluted mixture V2 is given by the sensor 20 = 0.01%, or 0.001 mlThe proportion of O2 in the initial volume V1 is = 0.001x100/0.0296 = 3.378%and from this we can deduce the volume V1 (100-99.704) 10ml = 2.96 ml:

Expiry route

For a third position 11 of valve 8 and for the generation means 3 exhausting gas flow 25, the means 3 to generate the gas flow are arranged to exhaust a leakage gas along the exhaust path, as shown in Figures 5 and 6.

Depending on the position of valve 16, the leakage gas (preferably from O2 or air) comes from the outer atmosphere or source 19.

At least one pressure sensor shall include an exhaust pressure sensor 5 arranged to measure a pressure Pr of the exhaust gas along the exhaust path, preferably but not limited to 20 to 500 mbar or wider, 4 to 500 mbar or 4 to 1000 mbar, and in any case within the limits of the load loss of the pneumatic circuit and the pressure resistance of the constituent parts of the invention.

The mass flow meter 4 is arranged to measure a representative parameter of the mass flow rate of the exhaust gas along the exhaust path.

The calculation means 7 are arranged to determine the size of a leakage hole 22 of sample 13 (into which the exhaust gas is introduced by the device 1) from a measurement of the mass flow representative parameter.

The exhaust pressure sensor 5 is located along the exhaust path between flow meter 4 and orifice 2.

The calculation means 7 are arranged to determine the size of the leakage hole 22 preferably in the form of a calculation which depends in an affine manner on the square root of the mass flow representative parameter (cf. first formula described above).

Alternatively, in the less precise case of a limited development of the first formula to order one, the means of calculation 7 are arranged to determine the size of the leakage hole 22 in the form of a calculation which depends in an affine manner on the representative parameter of the mass flow rate.

In general, in the case of a limited development of the first formula of the order Z (with Z an integer greater than or equal to 1), the means of calculation 7 are arranged to determine the size of the leakage hole 22 in the form of a polynomial of degree Z of the mass flow representative parameter

In this context, two variants of the invention, possibly combinable within the same device 1, are conceivable.

In a first variant, the calculation means 7 are arranged to determine the size of hole 22 further from a pressure measurement by the exhaust pressure sensor 5, e.g. in the form of a calculation that depends preferably in an affine manner on the inverse of the fourth root of the pressure measurement. with Dm the mass flow rate representative parameter measured by flow meter 4, Pr the pressure measured by exhaust pressure sensor 5, and a and b the numerical calibration coefficients.

According to the invention, leakage hole diameters 22 can then be measured typically down to a minimum of 0.05 μm.

In a second variant, Pr the pressure measured by the exhaust pressure sensor 5 is not taken into account in the calculation of the size of the leakage hole 22 but serves as a trigger ( trigger ): the means of calculation 7 are arranged to trigger a determination of the size of the hole 22 for a pressure value measured by the exhaust pressure sensor 5 corresponding to an exhaust pressure reference value, the means of calculation 7 being arranged to determine the size of the hole 22 from a value of the mass flow rate parameter Dm measured simultaneously with the pressure measurement at the pressure value corresponding to the exhaust pressure reference value. where Dm is the mass flow rate representative parameter measured by flow meter 4, and a and b are the numerical calibration coefficients.

The exhaled breathing path is divided into two parts which separate before the measuring hole 14 and join after the measuring hole 14: a first part passes through the measuring hole 14 (and includes sensor 6 and the measuring chamber between the measuring hole 14 and the passing hole 21) a second part does not pass through the measuring hole 14 so that the measuring hole 14 does not limit the flow of exhaled gas flow 25 in the exhaust path.

The exhaust path then passes successively through valve 16, generation means 3, flow meter 4, the two parts which separate before the measuring hole 14 and which join after the measuring hole 14, valve 8, pressure sensor 5, filter 23, and orifice 2.

The calibration path

At least one flow path includes a calibration path through orifice 2 which corresponds to the suction or dilution path. This calibration path narrows locally at the level of the measuring hole 14. When the generation means 3 generate a gas flow 25 (calibration gas) in suction or exhaust in this calibration path without orifice 2 being connected to a closed sample 13 (orifice 2 instead opening preferably to open air), the calculation means 7 are arranged to: 1) determine the size of the measuring hole 14 from a measurement of the mass flow rate representative parameter Dm by the flow meter 4,on the same principle as the determination of a leakage hole 22 described above, and2) adjust its numerical coefficients (typically a, b, a, etc.) for the calculation of a leakage hole 22 size if its determination of the φcal size of the measuring hole 14 does not match the actual size φr of the measuring hole 14 stored by the computing means 7, and (3) optionally re-iterate steps 1) and 2) if above until the determination of the measuring hole 14 size corresponds to a percentage error close to the actual size of the measuring hole 14 stored by the computing means.

Short-circuit path

Referring to Figures 7 and 8, valve 8 in its fourth position 12 is arranged to complete the exhaust path by a short-circuit path through office 2 and the flow generation means 3 but not through flow meter 4 (this short-circuit path is therefore not part of the flow paths as defined above). valve 8 is arranged to adjust the flow through the exhaust path and the short-circuit path in total. This allows for larger flow rates Dm, and thus to measure other leakage diameter troughs 22 or to rapidly inflate the sample 13 to test its strength until it is exhausted by a successive fatigue or stress phenomenon.

Typically, calculation method 7 simply multiplies the flow rate Dm measured by the mass flow meter 4 by a calibration coefficient to obtain the total flow through the exhaust path and the short-circuit path when valve 8 opens this short-circuit path. Or preferably, calculation method 7 changes the values of the calibration coefficients a and a when determining the size of the leakage hole 22 to take into account that the total flow through the exhaust path and the short-circuit path is greater than the measurement by the flow meter 4 of the flow parameter Dm representative of the mass flow of the leakage gas along the exhaust path.

The following is an example of a process whose sequence can be modified and implemented by the device 1 in Figures 1 to 8.

Dilution

First, before the exhaust of the analyte gas, the process involves exhausting (by means 3) the dilution gas (CO2 from source 19) flowing along the dilution path to sample 13 containing an initial gas (mixture of CO2 and NO2) which preferably but not necessarily includes the gas of interest.

Gas analysis

After dilution, the process of the invention involves aspiration (by means 3) of the analyte gas (O2 + CO2 + NO2) from sample 13, the aspirated analyte gas flowing along the aspiration path starting from orifice 2 and narrowing locally at the measuring hole 14.

During the suction process, the process simultaneously includes: a pressure measurement (more precisely a negative suction depression, a priori but considered as absolute value for calculations) Pr of the gas to be analysed along the suction path by sensor 6, preferably but not limited to -20 to -500 mbar or wider, 4 to 500 mbar or 4 to 1000 mbar or more depending on the capacity of the turbine 3;a measurement of a parameter representative of the mass flow rate of the gas to be analysed along the suction path by flow meter 4.

The method then includes a quantification by means of calculation 7 of the presence of the gas of interest (CO2 + NO2) in the gas to be analysed (O2 + CO2 + NO2), from this last measure of the representative mass flow parameter: e.g. proportion of CO2 + NO2 = 20% of the gas to be analysed after dilution.

The gas of interest (CO2 + NO2) comprises 0-100% of a first molecule of interest (CO2) having a certain thermal conductivity, and 0-100% of other molecules of interest (NO2) having a thermal conductivity which differs by more than 10% from the thermal conductivity of the first molecule of interest under identical temperature and pressure conditions.

The method also includes (simultaneously with the pressure measurement and the mass flow representative parameter) a quantification of the presence of the other molecules of interest (NO2) in the analyte gas (02 + CO2 + NO2) by means of the sensor 20 : e.g. proportion NO2 = 5% of the analyte gas after dilution.

The method also includes quantification of the presence of the first molecule of interest (CO2) in the analyte gas (02 + CO2 + NO2) from the quantification of the presence of the gas of interest (CO2 + NO2) in the analyte gas (02 + CO2 + NO2) and the quantification of the presence of the other molecules of interest (NO2) in the analyte gas (02 + CO2 + NO2) e.g. proportion of CO2 = 15% of the analyte gas after dilution.

The method also includes quantification of the presence of the first molecule of interest (CO2) in the starting gas (CO2 + NO2) from the quantification of the presence of the first molecule of interest (CO2) in the analysed gas (O2 + CO2 + NO2) and the quantification of the presence of the other molecules of interest (NO2) in the analysed gas (O2 + CO2 + NO2): for example, proportion of CO2 = 75% of the starting gas.

The method also includes quantification of the presence of other molecules of interest (NO2) in the starting gas (CO2 + NO2) from the quantification of the presence of the first molecule of interest (CO2) in the analysed gas (02 + CO2 + NO2) and the quantification of the presence of other molecules of interest (NO2) in the analysed gas (02 + CO2 + NO2) : for example, proportion NO2 = 25% of the starting gas.

Then comes the mechanical test of sample 13.

Calibration of leakage measurement

The process then involves a flow (generated by means 3) of a calibration gas (preferably from outside air or source gas 19) along the calibration path and, simultaneously with this flow: (1) a pressure measurement Pr of the calibration gas along the calibration path by sensor 5 or 6, preferably but not limited to 20 to 500 mbar or wider, 4 to 500 mbar or 4 to 1000 mbar; (2) a measurement of a parameter representative of the mass flow rate of the calibration gas along the calibration path;(a) a measurement of the size of the measuring hole 14 by the flowmeter 43) a determination of the size of the measuring hole 14 from this last measurement of the representative mass flow parameter by means of calculation 7, and (4) an adjustment by means of calculation 7 of calibration coefficients a, a, b for the calculation of a leakage hole size 22 if the φ troucal determination of the size of the measuring hole 14 does not correspond to an actual size φr of the measuring hole 14 stored by the calculation means, and (5) optionally a repetition of the previous steps 1 to 4.

Leakage measure

The process of the invention then involves exhausting the exhaust gas (preferably from outside air or source gas 19 or a tracer gas to locate the leak, colour or measurable by other external means) flowing along the exhaust path ending at orifice 2.

During the expiry of the term of the patent, the process of the invention shall simultaneously include: a pressure Pr measurement of the exhaust gas along the exhaust path by the sensor 5, preferably but not limited to 20 to 500 mbar or wider, 4 to 500 mbar or 4 to 1000 mbar, and in any case within the limits of the load loss of the pneumatic circuit and the pressure resistance of the constituent parts of the invention.a measurement of a parameter representative of the mass flow rate of the exhaust gas along the exhaust path by the flow meter 4.

The method according to the invention then includes a determination, by means of calculation 7, of the size of the leakage hole 22 in sample 13, from this last measurement of the representative mass flow parameter.

The determination of the size of the leakage hole 22 shall include a calculation as described for the description of the device 1.

If the leakage hole 22 is too large, the flow rate of the exhaust gas must be increased to reach a set pressure. The method according to the invention then involves adjusting, by the valve 8 arranged to complete the exhaust path by a short circuit path through the office and the flow generating means but not through the flow meter, the total flow through the exhaust path and the short circuit path, the said valve opening the short circuit path according to an adjustable size opening.

The method according to the invention then includes a determination, by means of 7, and from the flow measurement along the exhaust path, of the total flow through the exhaust path and the short-circuit path when the valve opens the short-circuit path.

More specifically, calculation method 7 modifies the value of the calibration coefficients a and a when determining the size of the leakage hole 22 to take into account the fact that the total flow through the exhaust path and the short circuit path is greater than the flow meter 4 measurement of the mass flow of the exhaust gas along the exhaust path.

The test shall be carried out on the test vessel.

After determining the size of the leakage hole 22, the gas flow rate is pushed to a high value, possibly at controlled flow rate to test the breakdown of sample 13 into the desired dynamics.

Sample 13 may be subjected to external mechanical stresses such as a bridging envelope, atmospheric pressure, immersion in a fluid, etc...

It is further noted that the different steps of this process can be reversed, or done simultaneously or be optional. For example, the calibration step is not necessary before the leakage measurement. Similarly, the leakage measurement is completely independent of the gas analysis, and the leakage measurement can be performed before the gas analysis or without the gas analysis.

Of course, the invention is not limited to the examples just described and many modifications can be made to these examples without going beyond the scope of the invention.

Claims (20)

1. Device for testing a sample (13) via a gas stream, comprising:

   - an opening (2),

   - means (3) for generating a gas stream (25) in the device along at least one flow path passing through the opening,

   - at least one pressure sensor (5, 6), each pressure sensor being arranged in order to measure a pressure of the gas stream along at least one flow path, and

   - a mass flowmeter (4), arranged in order to measure a parameter representing the mass flow rate of the gas stream along each flow path

   and wherein:

   - the at least one flow path comprises an exhaust path terminating at the opening,

   - the means for generating the gas stream are arranged in order to exhaust in the sample a leakage gas along the exhaust path,

   - the at least one pressure sensor comprises an exhaust pressure sensor (5) arranged in order to measure a pressure of the leakage gas along the exhaust path,

   - the mass flowmeter is arranged in order to measure a parameter representing the mass flow rate of the leakage gas along the exhaust path,

   and wherein the device is characterized in that it further comprises calculation means (7) arranged in order to determine the size of a leak hole (22), based on a measurement of the parameter representing the mass flow rate along the exhaust path the mass flowmeter being a mass flowmeter using thermal conductivity.
2. Device according to claim 1, characterized in that exhaust pressure sensor is situated along the exhaust path between the flowmeter and the opening.
3. Device according to any one of the preceding claims, characterized in that the calculation means are arranged in order to determine the size of the leak hole in the form of a calculation which depends linearly on the square root of the parameter representing the mass flow rate along the exhaust path.
4. Device according to any one of the preceding claims, characterized in that the calculation means are arranged in order to determine the size of the leak hole also based on a measurement of the pressure along the exhaust path by the exhaust pressure sensor.
5. Device according to claim 4, characterized in that the calculation means are arranged in order to determine the size of the leak hole in the form of a calculation which depends linearly on the inverse of the fourth root of the measurement of the pressure along the exhaust path.
6. Device according to claim 5, characterized in that the calculation means are arranged in order to determine the size of the leak hole according to the formula with D_m the parameter representing the mass flow rate, P_r the pressure measured by the exhaust pressure sensor, and a and b being numerical calibration coefficients.
7. Device according to any one of claims 1 to 3, characterized in that the calculation means are arranged in order to trigger a determination of the size of the leak hole for a value of the pressure along the exhaust path measured by the exhaust pressure sensor corresponding to an exhaust pressure reference value, the calculation means being arranged in order to determine the size of the leak hole based on a value of the parameter representing the mass flow rate along the exhaust path measured simultaneously with the pressure measurement measuring the pressure value corresponding to the exhaust pressure reference value.
8. Device according to claim 7, characterized in that the calculation means are arranged in order to determine the size of the leak hole according to the formula with D_m the parameter representing the mass flow rate, and a^∗ and b being numerical calibration coefficients.
9. Device according to any one of the preceding claims, characterized in that the at least one flow path comprises a calibration path passing through the opening, and in that within the device, said calibration path narrows locally at a measurement hole (14), the calculation means being arranged in order to:

   - determine the size of the measurement hole based on a measurement of the parameter representing the mass flow rate along the calibration path, and

   - adjust calibration coefficients for the calculation of a size of a leak hole if the determination of the size of the measurement hole does not correspond to an actual size of the measurement hole stored by the calculation means.
10. Device according to any one of the preceding claims, characterized in that it comprises a valve (8) arranged to complete the exhaust path via a short-circuit path passing through the opening and the stream generation means but not passing through the flowmeter, said valve being arranged in order to adjust the total flow rate passing through the exhaust path and the short-circuit path.
11. Process for testing a sample via a gas stream, comprising:

    - exhausting in the sample a leakage gas flowing along an exhaust path terminating in an opening (2) linked to the sample (13),

    - measuring the pressure of the leakage gas along the exhaust path,

    - measuring a parameter representing the mass flow rate of the leakage gas along the exhaust path, and

    the process being characterized in that it comprises:

    - determining the size of a leak hole (22) in the sample, based on the measurement of the parameter representing the mass flow rate along the exhaust path

    the measurement of a parameter representing the mass flow rate being a measurement by a mass flowmeter (14) using thermal conductivity.
12. Process according to claim 11, characterized in that the pressure measurement is carried out by an exhaust pressure sensor (5) situated along the exhaust path between the flowmeter and the sample.
13. Process according to any one of claims 11 to 12, characterized in that the determination of the size of the leak hole comprises a calculation of the size of the leak hole which depends linearly on the square root of the parameter representing the mass flow rate along the exhaust path.
14. Process according to any one of claims 11 to 13, characterized in that the determination of the size of the leak hole is carried out also based on the pressure measured along the exhaust path.
15. Process according to claim 14, characterized in that the determination of the size of the leak hole comprises a calculation of the size of the leak hole which depends linearly on the inverse of the fourth root of the measurement of the pressure along the exhaust path.
16. Process according to claim 15, characterized in that the determination of the size of the leak hole comprises a calculation of the size of the leak hole according to the formula with D_m the parameter representing the mass flow rate, P_r the pressure measured, and a and b being numerical calibration coefficients.
17. Process according to any one of claims 11 to 13, characterized in that the determination of the size of the leak hole is triggered in the case of a measured value of the pressure along the exhaust path corresponding to a pressure reference value, the determination of the size of the leak hole being carried out based on a value of the parameter representing the mass flow rate along the exhaust path measured simultaneously with the pressure measurement measuring the pressure value corresponding to the pressure reference value.
18. Process according to claim 17, characterized in that the determination of the size of the leak hole comprises a calculation of the size of the leak hole according to the formula with D_m the parameter representing the mass flow rate, and a^∗ and b being numerical calibration coefficients.
19. Process according to any one of claims 11 to 18, characterized in that the at least one flow path comprises a calibration path passing through the opening and narrowing locally at a measurement hole, the process according to the invention comprising:

    - a calibration gas flowing along the calibration path,

    - a pressure measurement of the calibration gas along the calibration path,

    - a measurement of a parameter representing the mass flow rate of the calibration gas along the calibration path,

    - a determination of the size of the measurement hole based on a measurement of the parameter representing the mass flow rate, and

    - an adjustment of numerical coefficients for the calculation of a size of a leak hole if the determination of the size of the measurement hole does not correspond to an actual size of the measurement hole stored by calculation means.
20. Process according to any one of claims 11 to 19, characterized in that it comprises an adjustment, by a valve (8) arranged in order to complete the exhaust path via a short-circuit path passing through the opening and the stream generation means but not passing through the flowmeter, of the total flow rate passing through the exhaust path and the short-circuit path.