Non-invasive system for monitoring a medical gas distribution network

Abstract

Title of the invention: Non-invasive system for monitoring a medical gas distribution network. The invention relates to a non-invasive system for monitoring a gas distribution network arranged in a hospital setting, comprising a gas source (1) connected to a main gas line (21) branching into several secondary gas lines (31, 32), downstream of a pressure regulating device (23). Strain gauges (6, 6a, 6b) are arranged on the gas lines (21, 31, 32). Temperature measurement means (68) are arranged on one or more gas conduits (21, 31, 32) to measure the temperature of the gas conduit (21, 31, 32), and provide these measurements to a control unit (64) which determines a resistivity (R) of each gauge (6, 6a, 6b) from the deformation of the resistive track (62) of the gauge (6, 6a, 6b) considered, a reference resistivity value (Ro), and the temperature measurements.The gas pressure exerted in the gas conduit (21, 31, 32) is determined from the resistivity (R) of each gauge (6, 6a, 6b). Gas supply installation (100) including such a monitoring system. Figure from the abstract: Fig. 2.

Description

Title of the invention: Non-invasive system for monitoring a medical gas distribution network

[0001] The invention relates to a non-invasive monitoring system for a gas distribution network in a hospital setting, enabling the provision of information relating to the distribution of gases in one or more departments of the hospital setting, in particular to alert in the event of localized overload, i.e. overpressure of a portion of the gas distribution network.

[0002] In healthcare facilities, such as hospitals, clinics or others, it is necessary to bring medical gases, in particular medical-grade air and oxygen (O2), to the various points of use within these facilities, for example, intensive care or emergency departments, operating rooms...

[0003] Generally, medical gases are stored in large capacity tanks or storage vessels, arranged outside the hospital establishment, which are replenished with gas by tanker trucks used to transport the gases from their production site to the hospital establishments.

[0004] The gases are then distributed to the various points of use, i.e. the various hospital departments, by means of gas pipes, lines or pipelines, commonly referred to as the "gas distribution network" or "gas network".

[0005] Monitoring the distribution of medical gases in hospital establishments is essential to be able to know the specific consumption of the different departments and to manage restocking in order to avoid any disruption of gas supply which could compromise the safety of patients, as during the Covid-19 pandemic, where the consumption of medical gases, in particular oxygen (O2), was increased tenfold due to a very large and unusual influx of patients to be treated.

[0006] Furthermore, the emergence of new patient care techniques, such as high flow oxygenation or "HFOT" (for High Flow Oxygen Therapy), has exacerbated the need for large volumes of oxygen, particularly in intensive care units, and therefore the implementation, once again, of close monitoring of hospital gas distribution networks and their consumption.

[0007] Now, a gas distribution network is designed to deliver, over a given flow rate range, a nominal gas pressure to the various gas distribution outlets, i.e., the hospital wall outlets, which it supplies with gas. These wall outlets are located in the departments or rooms of the hospital. These wall outlets ensure the smooth connection and gas supply to devices Medical devices, such as flowmeters, medical ventilators, and high-flow oxygen delivery systems, are used to supply gas to patients who need it. An example of a hospital wall outlet is provided by EP-A-3922895.

[0008] It is the responsibility of the technicians installing the medical gas network and the technical managers of the hospital or similar facility to determine the expected consumption (with a safety factor) in order to size the medical gas network, in particular to correctly choose the diameter of the gas or similar pipes, in order to guarantee a nominal gas pressure within the desired flow rate range, especially according to the needs of each hospital department, which vary from one department to another. Generally, the nominal operating pressure is in the range of 4 to 5 bar relative, as recommended by ISO 7396-1.

[0009] However, despite the precautions taken during the installation of a medical gas network, it sometimes happens that in the event of a peak in consumption, the medical gas network cannot meet the demand for gas and therefore maintain the nominal pressure, which leads to the malfunction of medical devices connected to wall sockets since they are then "under-supplied" with gas.

[0010] It is understood that this lack of gas, e.g. oxygen, creates a safety problem for patients and also significant stress for healthcare staff, particularly when the demand for gas is very high, such as during the Covid-19 pandemic or during "HFOT" type treatment.

[0011] To address this, EP1983251 proposes installing flow meters at various locations within the medical gas distribution network to monitor the gas distribution network, i.e., the gas distribution itself. Indeed, by knowing the gas consumption levels and the nature of the network, it is possible to detect any increase in gas consumption by a given department and thus anticipate future saturation of that department. This allows for the early redirection of patients to other departments where gas demand is lower, thereby preventing gas supply disruptions.

[0012] However, having to install flowmeters at different points or sites in the gas network of existing hospital facilities is not ideal because it requires, at the different sites of the network to receive a flowmeter, interrupting, i.e. cutting, the conduit of the network in order to install the flowmeter, which can lead to the entry of dust or other pollutants into the conduit or the gas network and thus generate a risk of malfunction of the equipment located downstream, or even lead to accidents, such as fires or others, in particular in the presence of oxygen.

[0013] Furthermore, interrupting a gas network pipe in an existing hospital facility necessitates the implementation of an alternative gas supply solution. in order to ensure continuity of gas supply to patients throughout the duration of their procedures or treatments, which generates logistical, organizational constraints and / or is not always possible or easy to implement.

[0014] Therefore, a problem is to be able to operate an effective monitoring of a gas distribution network within a hospital establishment, typically an existing hospital gas distribution installation, without having to interrupt the conduits of the hospital installation network and / or while ensuring a continuity of gas supply to patients, that is to say, to be able to measure the consumption of medical gases at different places in the gas distribution network in question, without encountering the aforementioned disadvantages.

[0015] One solution of the invention relates to a monitoring system for a gas distribution network arranged within a healthcare establishment, such as a hospital, clinic, care center or similar, comprising: - a gas source fluidly connected to a main gas conduit, - a pressure regulating device arranged on the main gas line, the main gas line branching into several secondary gas lines downstream of the pressure regulating device, said main and secondary gas lines carrying pressurized gas, and - strain gauges arranged downstream of the pressure regulating device, on the main and / or secondary gas lines.

[0016] Furthermore, the monitoring system of the invention also includes: - Temperature measurement means are arranged on at least one of the gas pipes, downstream of the pressure regulating device, in order to perform at least one temperature measurement of said gas pipe, said temperature measurement means being configured to provide said at least one temperature measurement to at least one control unit, - each strain gauge comprises a deformable resistive track configured to deform proportionally to the gas pressure exerted in the gas duct on which the strain gauge is arranged, the strain gauges each being associated with the control unit, and - The control unit is configured to: a. determine a resistivity (R) of each strain gauge from the deformation of the resistive track of the strain gauge in question, a reference resistivity value (Ro), and said at least one temperature measurement provided by the temperature measuring means, and b. determine at least one gas pressure from the resistivity (R) of each strain gauge, each determined gas pressure reflecting the gas pressure exerted in the gas conduit on which the strain gauge in question is arranged.

[0017] Depending on the embodiment considered, the monitoring system of the invention may include one or more of the following features: - It is non-invasive. - the means of temperature measurement include at least one temperature sensor connected to the control unit. - the (or each) control unit includes at least one (micro)processor. - the gas pipes are made of a copper alloy. - preferably, the gas pipes are made of a Cu-DHP type copper alloy. - the resistivity (R) of each strain gauge is determined by taking into account said at least one temperature measurement (T) and a stored reference temperature (To). - the (or each) control unit is configured to determine a temperature resistivity from said at least one temperature measurement (T) and a stored reference temperature (To). - the resistivity (R) of each strain gauge is determined by taking into account said at least one temperature measurement (T), a (the) coefficient of thermal expansion of the copper alloy and a stored reference temperature (To). - each strain gauge comprises a deformable resistive track arranged on a support including fastening means allowing attachment to the external peripheral wall of a gas duct. - the or each control unit is configured to determine, from the determined resistance value R, from said at least one temperature measurement provided by the temperature measurement means and from a database giving a correspondence between pressure and resistance R, the gas pressure prevailing in said main and secondary gas conduits carrying pressurized gas arranged downstream of the pressure regulating device. - it includes means of memorization to store the reference resistivity value Ro and the database. - the stored reference temperature (To) is stored by the storage means. - the coefficient of thermal expansion of the copper alloy is stored by the storage means. - the control unit or units are configured to determine the flow rate(s) of gas flowing in the first secondary conduit and / or in the second secondary conduit carrying pressurized gas arranged downstream of the pressure regulating device, from at least one pressure measurement having been determined. - the gas source contains oxygen or air.

[0018] According to certain embodiments, the monitoring system of the invention may also include one or more of the following features: - where each control unit cooperates with a telecommunications module. - each control unit and telecommunications module are configured to ensure data transmission, via said telecommunications module, from the control unit to at least one remote data processing platform, said data including at least one gas pressure determined by the control unit. - the gas distribution network includes gas pipes arranged in the hospital establishment, in particular on the walls of the hospital establishment, i.e. walls, partitions or the like. - the gas pipes have an external diameter between 10 and 50 mm, preferably around 15 mm. - gas pipes have an internal diameter between 12 and 14 mm, for example 12.6 mm, 13 mm or 13.6 mm. - gas pipes have a wall thickness of between 0.5 and 1.5 mm, for example 0.7 mm, 1 mm or 1.2 mm. - the pressure regulating device is configured to control the pressure and ensure a stable pressure between 3 and 7 bar relative, preferably about 4 and 5 bar relative, advantageously equal to about 4 bar. - strain gauges include a reference gauge and one or more additional or secondary gauges. - Each additional strain gauge is paired with the reference strain gauge. - the strain gauges are fixed to / on the external peripheral surface of the gas pipes. - the control unit includes at least one microcontroller. - the (each) microprocessor or microcontroller of the (each) control unit is arranged on (at least) an electronic board. The electronic board(s) is arranged in the control unit(s). Each strain gauge comprises a deformable resistive track arranged on a support including fastening means allowing attachment to the external peripheral wall of a gas conduit. Each strain gauge comprises a resistive track arranged on a support, in particular a silicone or similar support. Each strain gauge includes a resistive track capable of deforming, i.e., contracting or expanding, when the wall of the gas conduit to which the strain gauge is fixed is deformed. The remote data processing platform includes a computer server, preferably a "cloud" server or similar. the telecommunications module is further configured to communicate in receive with an electronic device with a graphical interface configured to send data to the telecommunications module. The electronic device is a digital tablet, a multifunction phone or a laptop, or similar. The control unit is configured to determine, from the determined resistivity value R and a database giving a correspondence between pressure and resistivity R, the gas pressure prevailing in said main and secondary gas conduits carrying pressurized gas arranged downstream of the pressure regulating device. The control unit includes storage means for storing the reference resistivity value (Ro) and the database, or other data. The storage means include flash memory or similar; alternatively, the database is stored within the processor of the control unit(s). The control unit(s) is configured to determine the flow rate(s) of gas flowing in the first secondary conduit and / or in the second secondary conduit carrying pressurized gas arranged downstream of the pressure regulating device, from at least one pressure measurement. The remote data processing platform is configured to control a display on a display screen, the gas flow rate(s) flowing in the first secondary conduit and / or in the second secondary conduit. Strain gauges are electrically powered, in particular their resistive track. the gas source includes at least one gas storage tank in liquid or gaseous form, in particular air or liquid oxygen (LOX). a telemetry unit is associated with said gas storage tank in order to determine the quantity of residual gas in said gas storage tank, in particular a level of LOX. The telemetry unit is configured to transmit remotely, via a telecommunications network, to a gas supplier, measurements of residual gas quantity, in particular the LOX level. a gas vaporizer is arranged at the outlet, i.e. downstream, of said gas storage tank and configured to transform the LOX into gaseous oxygen, notably by heating the LOX. the downstream end of the main conduit branches at least into a first section or first secondary conduit and into a second section or second secondary conduit. the first secondary conduit comprises a plurality of initial sub-branches. the second secondary conduit comprises a plurality of secondary sub-branches. at least part of the first sub-branches and / or the second sub-branches are connected to wall outlets for gas distribution, in particular outlets for supplying gaseous oxygen or air. the resistive track of each strain gauge is configured so that its resistance or resistivity R is modified relative to a resting resistive value Ro proportionally to the deformation undergone by the resistive track in question. the resistive track of each strain gauge is configured to be modified in compression (R<R0) ou une tension (R> R0). The value of the resistance or resistivity R of the resistive track of each strain gauge is determined by the control unit, typically by the processor or microcontroller. an electrical power source supplies electrical current to each control unit, in particular a battery, especially rechargeable, or the mains (110 / 220V). The electrical power source also supplies electrical current to the strain gauges and telecommunication modules. Each strain gauge is configured to be configurable (i.e., parameter data) remotely via an independent device comprising a graphical interface and means of communication, including a digital tablet, a multifunction phone, a computer or similar device. The communication module of each strain gauge is configured to receive parameter data from the independent device. The parameters of each strain gauge include a unique strain gauge identifier (ID), the internal diameter Di, of the gas conduit on which the gauge is arranged, relative location information with respect to a reference strain gauge, a pairing data and / or a time data (i.e. timestamp). According to another embodiment, the processor of the control unit is programmed to directly include the parameters of each gauge. It includes a reference strain gauge arranged in the region of the main conduit branching site. It includes additional strain gauges arranged on the first and second secondary conduits. Each strain gauge is configured to send data to the processing platform in the form of sets or "packets" of data. Each data set or packet includes at least one pressure value. Each data set or package includes one or more additional data points chosen from a time-based data point (i.e. timestamp), a gauge identifier (ID), a gas conduit diameter, a reference strain gauge identifier, and a distance between the reference strain gauge and the strain gauge under consideration. The processing platform is configured to perform preprocessing of all or part of the data from the strain gauges, in particular a resynchronization of the pressures measured by the strain gauges. the processing platform is configured to also operate a processing of all or part of the data from the strain gauges to determine the flow rate(s) of gas circulating in the gas conduit(s), in particular in the first secondary conduit and in the second secondary conduit. The processing platform is configured to command a display of at least the specified data rate(s) on a display screen for a user, such as a network operator, responsible for effective monitoring. of the gas distribution network within the hospital establishment in question.

[0019] The invention will now be better understood with reference to the following detailed description, given by way of illustration but not limitation, with reference to the accompanying figures, among which:

[0020] [Fig-1] schematically illustrates an installation of a monitoring system according to the invention of a medical gas distribution network of a hospital facility supplied by a gas source and including strain gauges.

[0021] [Fig.2] schematically represents a strain gauge of the installation of [Fig. 1] allowing to measure in a non-invasive way the local pressure prevailing in a conduit delivering medical gas.

[0022] [Fig.1] schematically illustrates an embodiment of a monitoring system for a medical gas distribution network according to the invention, arranged on a gas supply installation 100, i.e. a pressurized gas supply installation, arranged within a hospital establishment, which network is supplied by a gas source 1, namely here a tank 11 for storing O2 in liquid and / or gaseous form stored in its internal volume 12.

[0023] A telemetry unit 13 continuously measures the level of liquid O2 in the storage tank 11 and transmits remotely, via a communication network, such as GSM, internet or other, the liquid O2 level measurements to a gas supplier in order to alert him when a predefined low threshold is reached so that he can come and refill the storage tank 11 with liquid oxygen brought by tanker truck or similar.

[0024] To transform liquid oxygen into gaseous oxygen, a gas vaporizer 10 is used, arranged downstream of the storage tank 11. The outlet of the gas vaporizer 10 is fluidly connected to an inlet 21a of an upstream portion 21 of a main supply line 2, i.e., a main gas pipeline, so as to supply it with gaseous oxygen. The upstream portion 21, with a first diameter DI, supplies (at 21b) a pressure regulator 23, such as a gas pressure reducing device, arranged on the main supply line 2 and fluidly connected to an outlet 21b of the upstream portion 21. Preferably, the first diameter DI is several tens of millimeters, for example, at least 40 mm.

[0025] The pressure regulator 23 is also connected to an upstream end 24a of a downstream portion 24 of the main gas conduit 2 in order to supply it with gaseous oxygen at a given pressure. In other words, the pressure regulator 23 guarantees, i.e., provides, a stable pressure in the downstream portion 24 of the main conduit 2, referred to as the "nominal pressure". of service”. Advantageously, the nominal service pressure is approximately between 4 and 5 bar relative, for example approximately 4 bar.

[0026] The downstream end 24b of the downstream portion 24 of the main conduit 2 branches (at 24b), i.e. divides, into a first section or first secondary conduit 31 having a second diameter D2 and, furthermore, into a second section or second secondary conduit 32 having a third diameter D3.

[0027] The main conduit 2 and the first and second secondary conduits 31, 32 form all or part of the gas distribution network of the hospital establishment, used in particular to supply gas to wall outlets, as explained below.

[0028] The first and second secondary conduits 31, 32 form a secondary gas circuit 3. They preferably have equal diameters D2, D3, for example, approximately 15 mm. According to one embodiment, we have: D2 <D1 et D3<D1.

[0029] The first secondary conduit 31 itself has a plurality of sub-branches 311-31n, respectively, forming gas lines terminating at wall-mounted oxygen outlets 41 and 41n, respectively, located in a department 4 of the hospital, for example, an intensive care unit. The gaseous oxygen circulating in the first secondary conduit 31 is therefore distributed to all or part of the sub-branches 311-31n depending on whether the wall-mounted O2 outlets 411-41n are in operation or at rest, i.e., connected or not to medical devices using oxygen, such as flowmeters, mechanical ventilators, high-flow oxygen delivery devices, etc.Similarly, the second secondary conduit 32 also supplies a plurality of sub-branches 321-32n, i.e. gas lines also leading to wall-mounted O2 outlets 421-42n located in another department 5 of the hospital establishment, for example a light care department.

[0030] The gas pressure exerted at the wall outlets must not be less than 90% of the nominal service pressure (e.g. 4 bar relative), therefore here at least 3.6 bar relative, when the medical gas distribution network is operating within its operational range, in order to avoid the risk of the medical devices connected to the wall outlets 41l-41n, 321-32n malfunctioning and endangering patients.

[0031] The operational range of the wall sockets must therefore be determined by taking into account the type of service equipped with wall sockets (e.g. emergency, resuscitation, minor care...), the estimated rate of use of the wall sockets (for example 75% use) and the flow rate of gas consumed through each of the wall sockets in operation.

[0032] For example, considering the first secondary conduit 31, for n (n>2) wall-mounted O2 outlets 411-41n in a resuscitation unit, it can be determined that 75% of the The outlets are used at any given time, for an average flow rate of 20 L / min. Thus, for 20 outlets (n=20), a total flow rate circulating in the first secondary conduit 31 can be considered to be on the order of a maximum of 300 L / min. Considering this maximum flow rate and the length of the first secondary conduit 31, for example, from several meters to several tens of meters, defined between the end 24b of the downstream portion 24 and the downstream end 31b of this first secondary conduit 31, it can be determined that a diameter D2 of 15 mm should allow compliance with the requirements of ISO 7396-1, in particular a pressure prevailing at the downstream end 31b of the first secondary conduit 31 greater than 90% of the nominal operating pressure (here 3.6 bar relative).

[0033] The same applies to the sizing of the second secondary conduit 32 supplying a light care service 5, for which it is determined that a maximum total flow rate of 320 L / min can also be observed (i.e. 100 intakes at 80% at 4L / min for example) and this, for a diameter D3 of the second secondary conduit 32 also of 15 mm.

[0034] In unusual or exceptional conditions, for example an influx of COVID patients...or other, on the one hand, the occupancy rate of the wall-mounted O2 outlets 411-41n may reach 100 and, on the other hand, to optimize the care of the patients concerned, their oxygenation must be ensured by high-flow oxygen delivery devices that consume O2, for example using 60 L / min, or even more.

[0035] This results in a total flow rate in the first secondary conduit 31 of approximately 420 L / min, well above the initially expected maximum flow rate. However, the pressure drop between the downstream end 2b of the portion 24 and the downstream end 31b of the first secondary conduit 31 varies proportionally to the square of the flow rate between these two points. It therefore becomes significantly lower than the minimum pressure of 3.6 bar, which causes malfunctions in the medical devices connected to the various wall-mounted oxygen outlets 411-41n in the intensive care unit 4 under consideration.

[0036] We can then understand the importance of being able to operate an effective monitoring of the gas distribution network, in particular of the first secondary conduit 31 and the second secondary conduit 32, in order to detect any saturation of the conduits and to warn, if necessary, an operator, for example the technical manager supervising the medical gas distribution network, of the imminence of such saturation of one and / or the other of these conduits.

[0037] According to the invention, the problems associated with inserting dedicated flow sensors into the medical gas distribution network of existing hospital facilities are avoided, which require interrupting the network conduits during the intervention, thus preventing continuity of gas supply to patients.

[0038] To do this, a set of non-invasive sensors 61, i.e. strain gauges 6, are implemented within the installation 100, which are part of a monitoring system according to the invention.

[0039] Thus, [Fig.2] schematically illustrates the principle of the arrangement of such strain gauges 6, preferably connected gauges, on a gas conduit 9 of a hospital gas delivery installation, such as the installation 100 of [Fig.1] according to the invention.

[0040] Each strain gauge 6 is electrically connected to a control unit 64, in particular a microprocessor electronic card 64.1 65, such as a microcontroller, via an electrically connected cable 63.

[0041] The strain gauge 6 comprises a support 61.1, such as a silicone substrate, or similar, carrying a deformable resistive track 62. This resistive track 62 is capable of deforming, i.e., contracting or expanding, under the action of a mechanical stress, in particular in the event of deformation of the wall 90 of the gas conduit 9 on which it is fixed, especially under the effect of an internal gas pressure.

[0042] Deformations of the resistive track 62 modify its resistance R (also called resistivity) relative to a resting resistive value Ro depending on the deformation undergone, i.e., depending on whether the resistive track 62 undergoes compression (R<R0) ou une tension (R> R0). The value of the resistance R of the resistive track 62 of the strain gauge 61 is determined by the control unit 64, typically by the processor 65 or microcontroller, arranged on the electronic board 64.1.

[0043] The determination of the resistance value R of the resistive track 62 is usually carried out using a Wheatstone bridge (https: / / en.wikipedia.org / wikiAVheatstone_bridge) controlled by the microprocessor 65 and the electronic board 64.1.

[0044] According to one embodiment, the installation 100 further comprises a telecommunications module 66 configured to transmit and / or receive data, i.e., information or other data. The telecommunications module 66 is preferably integrated into the electronic board 64.1.

[0045] More specifically, the telecommunications module 66 is configured to communicate in receive with an independent electronic device 7 comprising a graphical interface 71, such as a digital tablet, a multifunction phone (smartphone), a laptop or similar computer.

[0046] This electronic device 7 is configured to send data to the telecommunications module 66. When the telecommunications module 66 receives this data, it retransmits or transfers it to the control unit 64, which processes it. This data is used, in particular, to configure the strain gauge(s) 6.

[0047] The telecommunications module 66 is also capable of transmitting data, for example via cellular or other means, for example via a communication protocol of the LoRa or similar type, which data can then be captured, for example, by a receiving terminal (not shown) acting as a communication relay. Advantageously, once received, this data can be processed on a remote data processing platform, such as a cloud-based or similar computer server, and then provided, once processed, for example aggregated, to an operator, for example the technical manager of the medical gas distribution network in question, in particular displayed on a screen for the operator's attention.

[0048] The electronic board 64.1 of the control unit 64 is powered by a battery or by mains (110 / 220V), which allows the various components requiring power to be powered and controlled, in particular the strain gauge 61, the control unit 65 and the telecommunications module 66.

[0049] The strain gauge 6 is fixed to the external peripheral surface 91 of the gas conduit 9 by a suitable device or fastening means 61.2, for example a collar, clips or the like, which are attached to the strain gauge 6 by gluing, welding or the like, in particular attached to the deformable support 61.1 carrying the resistive track 62.

[0050] The conduit 9 is typically a copper conduit carrying a medical gas, such as O2. For example, it has an external diameter of approximately 15 mm and a wall thickness of approximately 1 mm. The diameters of medical gas conduits are standardized (EN 13348), and therefore there are only a limited number of possible diameters, among which the 15 mm diameter is the most commonly used for secondary conduits in hospital networks.

[0051] The medical gas, here O2, circulates at a given pressure P, for example of several relative bars, e.g. 4 bars, in the internal conduit 92 or lumen of the conduit 9.

[0052] The wall 90 of the conduit 9 will deform proportionally to the pressure of the gas it carries, that is to say that the diameter D of the conduit 9 increases proportionally to the gas pressure P prevailing in the internal passage 92 of the conduit 9. The rate of deformation depends not only on the gas pressure P in the conduit 9 but also on the diameter D and the thickness E of the wall 90 of the conduit 9, as well as on the mechanical properties of the material of the conduit 9, e.g. copper (cf. Young's modulus and Poisson's ratio).

[0053] More specifically, the relationship linking the gas pressure P to a given conduit corresponds to the following formula:

[0054] P = dEL-v) • P is the pressure in Pa • E is Young's modulus in GPa • Di is the internal diameter of the conduit in mm • A Di is the deformation of the conduit, measured by the gauges • t is the wall thickness of the duct in mm • v is Poisson's ratio, i.e., constant at 0.34 for alloys of copper.

[0055] As explained above, any gas distribution network in a hospital must comply with specific standards, such as the NF EN-13348 standard, which requires the use of pipes of varying diameters and wall thicknesses, as well as a specific copper alloy, typically Cu-DHP for hospital network pipes. Cu-DHP (for Phosphorus-Deoxidized Copper) is a copper alloy deoxidized with phosphorus. It typically contains between 0.013% and 0.040% phosphorus.

[0056] Thus, concerning the internal / external diameters and the wall thickness of the conduit considered, for a tube with an external diameter of 15 mm, the wall thickness can be equal, according to NF EN-13348, to 0.7 mm, 1 mm or 1.2 mm, which corresponds to an internal diameter Di of 13.6 mm, 13 mm or 12.6 mm, respectively.

[0057] The external diameter and wall thickness information of a hospital network duct is standardly indicated on its external surface (see EN-13348). The internal diameter Di can then be deduced from this.

[0058] These dimensional parameters (external and / or internal diameters and wall thickness) can be used when setting up the strain gauges and stored within the control unit 64, for example within storage means of the unit 64, in particular within its processor or a dedicated memory, such as a flash memory.

[0059] When subjected to pressure variations, the conduit 9 (i.e. its wall 90) deforms, in compression or tension, and these deformations propagate, in a (quasi-) instantaneous manner, to the resistive track 62 of the strain gauge 6, in particular through the wall 90 of the conduit 9 and the fastening means 61.2, which resistive track 62 then also deforms in correlation with these pressure variations.

[0060] In other words, as soon as the strain gauge 6 is installed on the conduit 9 and the latter is subjected to internal gas pressure, the resistive track 62 of the strain gauge 6 is put under tension due to the expansion of the conduit 9 under the effect of the pressure.

[0061] The control unit 64, in particular the processor 65, will then be able to determine the resistive value R, which is greater than the resting resistive value Ro of the resistive track 62, i.e. a reference resistance value Ro.

[0062] Then, the control unit 64 determines, from the determined resistance value R and a stored database, the gas pressure P prevailing in the gas conduit 9, for example carrying medical oxygen.

[0063] Preferably, the database is obtained beforehand, for example during the manufacturing process of the gauge 6 or subsequently via routine tests, by correlating resistive values ​​R of the resistive track 62 with different diameters of gas ducts subjected to different pressures P, thus causing more or less significant deformations, for example pressures from 0 bar relative (i.e., atmospheric pressure) to 10 bar relative. Ro denotes the resistance value corresponding to a gas duct subjected to atmospheric pressure (1 atm = 0 bar relative).

[0064] For example, all the conduits referenced in NF EN-13348, i.e. of different diameters and wall thicknesses, can be used to constitute the database and make it an exhaustive database.

[0065] It is noted that, in addition to the dimensional data of the conduit, i.e. internal diameter Di and wall thickness t, the calculation formula above includes Young's modulus, which represents the rigidity of a material under elongation (which is similar to an "elasticity").

[0066] However, the value of this coefficient depends on the alloy considered, for example a copper alloy. For example, the Cu-DHP alloy, which is generally used for hospital conduits, has a Young's modulus of approximately 130 GPa at 20°C, while the CW114C alloy has a Young's modulus of approximately 120 GPa at 20°C, which can result in a pressure error of 10% on the pressure measurement prevailing in the conduit.

[0067] Therefore, it is necessary that the database be made on conduits having the alloy specified in NF EN-13348, i.e. CuDHP, so that the relationship between the deformation under pressure of a given conduit is as accurate as possible.

[0068] We will see later the advantage of the database being created under a controlled temperature condition, for example at 20°C, and of this temperature To being stored within the control unit 64, for example within storage means of unit 64.

[0069] In summary, depending on a given conduit (internal diameter Di and wall thickness t), at a given control temperature T0, the database links a deformation measurement of said conduit (being represented by the measured resistive value R) to the pressure P prevailing in said conduit.

[0070] The database is preferably integrated, i.e. stored, directly within the processor 65 of the control unit 64, or, as appropriate, in a dedicated memory, such as a flash memory, cooperating with the processor 65.

[0071] Advantageously, after being positioned on the gas conduit 9, the connected strain gauge 6, i.e., the (tele)communicating strain gauge, is preferably configured via the graphical interface 71 of the independent device 7, such as a digital tablet or similar device. The configuration data is then transmitted remotely via the tablet or similar device's communication means to the communication module 66, as already explained.

[0072] The installation 100 of [Fig.1] incorporating a monitoring system according to the invention preferably comprises several strain gauges 6, 6a, 6b in order to monitor different points of the gas network, typically a reference strain gauge 6 and several additional or secondary strain gauges 6a, 6b.

[0073] In this case, the parameters of each strain gauge 6, 6a, 6b, i.e. the parameterization data, from the device 7 of the digital tablet or analog type, can be fixed or selected by an operator and include a unique identifier (ID) of each strain gauge 6, 6a, 6b, the diameter Di of the gas conduit on which they are installed, relative location information of the reference strain gauge 6 and the additional strain gauges 6a, 6b, strain gauge pairing data, and even other useful information, in particular time data, i.e. a timestamp.

[0074] According to another embodiment, the processor 65 of the control unit 64 is programmed to directly include the parameters of each gauge, such as its unique identifier (ID), the internal diameter Di of the gas conduit to which the strain gauge(s) is attached, and / or other parameters, including those described below, used to improve the accuracy of measurement / determination of pressures and flow.

[0075] Once the pressure value P is determined, the control unit 64 is configured to transmit this pressure, along with the timestamp and unique identifier of the gauge in question, the diameter D of the gas conduit 9, the pairing with other strain gauges, and the location information, to a remote computer platform 8 for further processing and use of the information. The data transmission can be carried out at a given frequency, for example every 10 milliseconds, or at another suitable frequency.

[0076] In other words, [Fig.1] according to the invention schematizes an integration in a hospital installation 100 comprising a network of medical gas distribution conduits, of a monitoring system comprising several strain gauges connected 6, 6a, 6b, in accordance with [Fig.2], on the secondary circuit 3 of the hospital medical gas distribution network.

[0077] These connected strain gauges 6, 6a, 6b are arranged here by way of example in the region of the branching site 24b of the main conduit 21 and elsewhere on the first and second secondary conduits 31, 32, in order to measure the distribution of gas flow rates. They function like the one described above, with reference to [Fig.2]; however, they could be arranged in other locations in the network.

[0078] These strain gauges 6, 6a, 6b, in particular the processors 65 of the control unit(s) 64 associated with these strain gauges 6, 6a and 6b, have been configured, for example, via the graphical interface device 71, such as a digital tablet or similar device. These strain gauges 6, 6a, 6b, or more precisely the processors 65, preferentially send all the aforementioned data to the data processing computer platform 8.

[0079] As illustrated in [Fig. 1], the main strain gauge 6, which serves as a reference gauge, can be installed on the secondary network 3 at the downstream end of the downstream portion 24 of the main conduit 21, for example at its branch (at 24b) into said first and second secondary conduits 31, 32 or on the downstream section or portion 24 of the main conduit 21. Furthermore, the first additional strain gauge 6a is arranged at the downstream end 31b of the first secondary conduit 31, and the second additional strain gauge 6b is installed at the downstream end 32b of the second secondary conduit 32. In other words, the main strain gauge 6 is arranged here between the additional strain gauges 6a, 6b.

[0080] During the parameterization of the strain gauges 6, 6a, 6b, the diameters Di2, Di3, which are identical, for example of the order of 13 mm, are entered (in addition to the wall thickness of the conduits on which they are placed) via the digital tablet or any similar device 7, which makes it possible to determine the local pressure prevailing in the secondary conduit 3 at the location sites of the strain gauges 6, 6a, 6b.

[0081] By way of example, the data relating to each of the connected strain gauges 6, 6a, 6b can be sent to the processing platform 8 in the form of data packets: - Reference gauge 6: [T, Jl, Dil, PI, 0, 0] - First additional gauge 6a: [T, J2, Di2, P2, RefJl, Ll] - Second additional gauge 6b: [T, J3, Di3, P3, RefJl, L2]

[0082] where: - T is a time data, i.e. a timestamp, for example of the form DD / MM / YY XXhXXminXXsXXms. - Jl, J2, J3 are the unique identifiers (ID) of gauges 6, 6a, 6b. - Dil, Di2, Di3 are the internal diameters of the medical gas lines on in which gauges 6, 6a, 6b are installed. - PI, P2, P3 are the local pressures prevailing in the conduits at the level of the gauges 6, 6a, 6b considered. - RefJl is the identifier of the reference strain gauge 6 (ID = Jl) to which the additional strain gauges 6a, 6b are matched. - L1, L2 are the distances (in meters) separating the additional strain gauges 6a, 6b from the reference gauge 6.

[0083] Since the reference strain gauge 6 is the reference point for the additional strain gauges 6a, 6b, it is not paired with any other connected strain gauge, therefore its pairing is designated by "0" and its relative location is also designated by "0" in the data packet that concerns it.

[0084] By way of illustrative example, it is considered that the pressure at the level of the reference strain gauge 6, i.e. prevailing at the downstream end 24b of the downstream portion 24, is 4.5 bar, while the pressure prevailing in the first secondary conduit 31 at the level of the strain gauge 6a is 4.2 bar, and that prevailing in the second secondary circuit 32 at the level of the strain gauge 6b is 3.8 bar.

[0085] As explained above, the resistive track 62 of the strain gauges 6, 6a, and 6b will reflect a resistive value corresponding to the pressure-induced deformation of the various conduits on which the strain gauges 6, 6a, and 6b are arranged. The processors 65 of the control unit 64 associated with the various strain gauges 6, 6a, and 6b are then able to convert the different resistive values ​​of the resistive tracks 62 into pressure, namely a pressure of 4.5 bar for strain gauge 6, a pressure of 4.2 bar for strain gauge 6a, and a pressure of 3.8 bar for strain gauge 6b.

[0086] If the distance between the reference strain gauge 6 and the first strain gauge 6a is 50 meters, and that between the second strain gauge 6 and the strain gauge 6b is 30 meters, the electronics, i.e. processors 65 of the control units 64, of the strain gauges 6, 6a and 6b will send at a given frequency, for example every 10ms, "packets" or sets of data to the processing platform 8, such as a remote computer server, as illustrated in [Table 1] below.

[0087] [Table 1] Gauge Time Stamp ID Di (mm) P (bar) Ref. L (m) 6 14 / 4 / 2000 10:40:37 150ms Jl 13 4.5 0 0 6a 14 / 4 / 2000 10:40:37 150ms J2 13 4.2 Jl 50 6b 14 / 4 / 2000 10:40:37 150ms J3 13 3.8 Jl 30

[0088] When these data sets are received at the processing platform 8, it is possible to extract the flow rates circulating respectively in the first and second secondary conduits 31, 32.

[0089] Indeed, any flow circulating in the internal diameter Di of a given conduit results in a pressure loss which is a function of the nature of the medium (in the example here of gaseous O2), the diameter of the conduit, the length of the conduit and the flow circulating in the conduit considered.

[0090] Thus, knowing the nature of the gas (i.e., oxygen) flowing in the first secondary conduit 31, the pressure difference between the connected strain gauges 6 and 6a, the diameter Di2 of the first secondary conduit 31, and the length separating the connected strain gauges 6 and 6a, it is possible to determine the flow rate in the first secondary conduit 31 by applying the Darcy-Weisbach equation, for example. See, for example, the Wikipedia page which provides this equation: https: / / en.wikipedia.org / wiki / Darcy%E2%80%93Weisbach_equation).

[0091] Advantageously, pretreatment can be carried out on the processing platform 8 by resynchronizing the pressures measured by the connected strain gauges 6, 6a.

[0092] Indeed, under the action of an instantaneous flow rate, the propagation of the pressure wave from point A to point B occurs only at the speed of sound. If a fixed instantaneous flow rate, for example 100 L / min, appears at the connected reference strain gauge 6, the pressure drops at the additional strain gauge 6a to reach a stable value, after the sound wave has traveled between the strain gauges 6 and 6a. Since the distance separating these gauges is 30 meters and the speed of sound is approximately 330 m / s, the pressure at the connected strain gauge 6a is established after a latency time of approximately 90 milliseconds (msec).During pressure resynchronization, the processing algorithm(s) deployed on the processing platform 8 take into account this latency time between the paired strain gauges in order to avoid returning erroneous flow values ​​circulating in the medical gas distribution network.

[0093] By exploiting the data returned by strain gauges 6, 6a, 6b, it is possible to determine, in the platform 8, the flow rates circulating in the first secondary conduit 31 and in the second secondary conduit 32. These flow rates and other data (IDs, pressure...) can then be displayed on a display screen for a user, such as a network operator, responsible for the effective monitoring of the gas distribution network within the hospital establishment in question.

[0094] Estimating the flow rates in portions of the medical gas distribution network is not limited to straight, i.e., linear, portions. Indeed, the equation Transforming a pressure loss into a flow rate can take into account possible changes in cross-section, the presence of bends...

[0095] Using strain gauges attached to the gas lines of the network is advantageous because their installation on existing networks does not require interrupting the lines of the hospital installation network, regardless of the network sites chosen for their installation, and therefore ensures continuity of gas supply, in particular oxygen supply to patients in need.

[0096] From the information / data collected and / or calculated, it is possible to determine and display a score, for example a saturation rate of each of the portions of a medical gas distribution network considered, in order to warn of the imminence of network saturation and thus allow the operator to take appropriate protective measures.

[0097] In other words, the invention is based on the use of strain gauges arranged on the external surface of the gas pipes of a gas distribution network within a hospital establishment in order to monitor this gas distribution network and to estimate the pressure and then the flow rate in said pipes.

[0098] Furthermore, it is also observed that the thermal expansion of copper can also influence the pressure calculation, as can be seen from the formula above.

[0099] Indeed, the Cu-DHP alloy exhibits an expansion of 17.7 pm / (m °C). In other words, for 1 meter of copper, a deformation of 17.7 pm is to be expected per degree Celsius. The deformation is in the direction of contraction for a negative variation of 1°C and in the direction of elongation for a positive variation of 1°C.

[0100] Thus, taking as an example a conduit with an internal diameter of 13 mm Di at 20°C (i.e. 1 mm wall thickness), a deformation of this internal diameter of 0.3 pm is obtained for a pressure variation of 1 bar, whereas a deformation of the internal diameter of 0.23 pm is expected for a variation of 1°C.

[0101] It is understood that the deformation is not necessarily negligible and should preferably be compensated to refine the pressure calculations.

[0102] Since the expansion is closely related to the temperature to which the conduit in question is subjected, according to the invention, temperature measurement means 68, typically a temperature sensor or similar, are arranged on the external surface of the gas conduit in question, as illustrated in [Fig.2], and are connected to the control unit 64, for example via a connecting cable 67 or similar, so that they provide it with the pressure measurements they operate.

[0103] The temperature sensor, i.e. the temperature measuring means 68, can be fixed to the external surface of the gas conduit 9 by bonding with thermal paste or by any other suitable fixing technique.

[0104] For example, the LMT70A reference temperature sensor available from Texas Instrument.

[0105] The coefficient of thermal expansion relating to the copper alloy considered, here 17.7 pm / (m °C) for the Cu-DHP alloy, is also stored in the control unit 64.

[0106] Depending on the characteristics of the conduit (internal diameter, wall thickness), the microprocessor 65 of the control unit 64 is then able to exploit the temperature measurement and compensate for the effect of temperature on the deformation of the conduit by using this temperature value to compensate for the resistivity determined from the stored reference table, as explained above.

[0107] Taking the example of gauge 6a, which is installed on a conduit with an internal diameter Di2 of 13 mm and a wall thickness of 1 mm, the actual pressure in the conduit is 4 bar. The microprocessor 65 of the control unit 64 measures a resistive value R which, according to the database, corresponds to a pressure of 7.6 bar.

[0108] Now, this resistive value R can be represented by two components, namely the RP component which is linked to the pressure prevailing in the conduit, which induces a deformation of the conduit, and that resulting from the thermal expansion (or contraction) RT with respect to the reference temperature To used when establishing the database, for example To = 20°C.

[0109] Schematically, we therefore have: R = RP + RT.

[0110] The RT component is undesirable and must be compensated to consider only the RP resistivity value due to pressure.

[0111] To do this, the microprocessor 65 of the control unit 64 measures the temperature T prevailing at the level of the conduit, via the temperature measuring means 68. For example, the temperature T may be equal to 21°C, for example, therefore considered to be 1°C higher than the stored reference temperature To (i.e. 20°C).

[0112] Furthermore, the value or coefficient of thermal expansion of the alloy used, for example 17.7 pm / (m °C) here for the Cu-DHP alloy, being stored within the control unit 64, knowing the difference between the temperature T and the stored reference temperature To, the microprocessor 65 of the control unit 64 is able to transform this temperature difference into a deformation.

[0113] The microprocessor 65 can then determine that the effect of ambient temperature results in a resistivity value RT and can therefore subtract this resistivity value RT from the measured resistivity value R in order to determine the resistivity value RT. The corrected resistivity value retained is therefore equal only to that generated by the pressure (RT).

[0114] Knowing this corrected resistivity value, the microprocessor 65 can then perform a temperature compensation of the resistivity and thus determine a corrected and correct pressure value P, namely here a pressure value equal to 4 bar.

[0115] Otherwise, the control unit 64 incorporates storage means and computing means to perform temperature compensation of the resistivity determined from the measurements provided by the strain gauges 6, 6a, 6b.

[0116] Thanks to this, it is possible not only to refine the measurements taken by the gauges by taking better account of the characteristics of the conduits but also to obtain a more precise resistivity value, therefore a better estimation of the resulting pressures and flow rates.

[0117] In general, the present invention is applicable to any gas distribution network within a hospital building, in particular the medical oxygen distribution network and the medical air distribution network, supplying the wall gas supply outlets to which medical devices are connected, provided that these networks are identical or similar in terms of construction and are otherwise subject to the same normative requirements, in particular in terms of nominal distribution pressure and / or minimum supply pressure of the wall outlets.

Claims

1. Demands Monitoring system for a gas distribution network arranged within a hospital facility, comprising: - a gas source (1) fluidly connected to a main gas conduit (21), - a pressure regulating device (23) arranged on the main gas line (21), the main gas line (21) branching into several secondary gas lines (31, 32) downstream of the pressure regulating device (23), said main (21) and secondary (31, 32) gas lines carrying pressurized gas, and - strain gauges (6, 6a, 6b) arranged downstream of the pressure regulating device (23), on the main and / or secondary gas lines (21, 31, 32), characterized in that: - temperature measuring means (68) are arranged on at least one of the gas pipes (21, 31, 32), downstream of the pressure regulating device (23), in order to perform at least one temperature measurement of said gas pipe (21, 31, 32), said temperature measuring means (68) being configured to provide said at least one temperature measurement (T) to at least one control unit (64), - each strain gauge (6, 6a, 6b) comprises a deformable resistive track (62) configured to deform proportionally to the gas pressure exerted in the gas conduit (21, 31, 32) on which the strain gauge (6, 6a, 6b) in question is arranged, the strain gauges (6, 6a, 6b) each being associated with the control unit (64), and - The control unit (64) is configured to: a. Determine a resistivity (R) of each strain gauge (6, 6a, 6b) from the deformation of the resistive track (62) of the strain gauge (6, 6a, 6b) under consideration, a reference resistivity value (Ro), and said at least one measurement of temperature supplied by the temperature measuring means (68), and b. determine at least one gas pressure from the resistivity (R) of each strain gauge (6, 6a, 6b), each determined gas pressure reflecting the gas pressure exerted in the gas conduit (21, 31, 32) on which the strain gauge (6, 6a, 6b) in question is arranged.

2. System according to claim 1, characterized in that the temperature measurement means (68) comprise at least one temperature sensor connected (67) to the control unit (64).

3. System according to claim 1, characterized in that the gas conduits (21, 31, 32) are made of a copper alloy, preferably a Cu-DHP type copper alloy.

4. System according to claims 1 and 3, characterized in that the resistivity (R) of each strain gauge (6, 6a, 6b) is determined by taking into account said at least one temperature measurement (T), a coefficient of thermal expansion of the copper alloy and a stored reference temperature (To).

5. System according to claim 1, characterized in that each strain gauge (6, 6a, 6b) comprises a deformable resistive track (62) arranged on a support (61.1) comprising fastening means (61.2) allowing attachment to the outer peripheral wall of a gas conduit (21, 31, 32).

6. System according to claim 1, characterized in that the control unit (64) is configured to determine, from the determined resistivity value R, from said at least one temperature measurement provided by the temperature measurement means (68) and from a database giving a correspondence between pressure and resistivity R, the gas pressure prevailing in said main (21) and secondary (31, 32) gas conduits carrying pressurized gas arranged downstream of the pressure regulating device (23).

7. System according to claim 6, characterized in that it includes storage means for storing the reference resistivity value (Ro) and the database.

8. System according to claim 1 or 6, characterized in that the control unit (64) is configured to determine the flow rate(s) of

9.

10. gas circulating in the first secondary conduit (31) and / or in the second secondary conduit (32) carrying pressurized gas arranged downstream of the pressure regulating device (23), from at least one pressure measurement having been determined. System according to claim 1, characterized in that the gas source (1) contains oxygen or air. Gas supply installation (100) comprising a network of gas distribution conduits arranged within a hospital establishment, used to convey gas under pressure, said gas distribution network comprising the main gas conduit (21) branching into secondary gas conduits (31, 32), characterized in that it comprises a distribution network monitoring system according to one of the preceding claims.

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