Autonomous and irreversible pressure change detection device

Abstract

The present invention relates to a pressure change detection device for detecting a sudden change in pressure in a fluid, the pressure change detection device (1) comprising: a shell (20) with one end open, a screen (10) closing the shell (20) to create a chamber (30), the screen (10) being configured such that when the external pressure of the chamber (30) is substantially stable or changes slowly, the internal pressure of the chamber (30) is close to the external pressure, and the screen (10) has a mechanical property that causes it to rupture when subjected to a predetermined difference between the external pressure and the internal pressure.

Description

Technical Field

[0001] The present invention relates to a sensor for sudden pressure changes in a fluid, and more particularly to an irreversible detector for pressure changes in a fluid. Background Art

[0002] In many fields, for safety reasons or to prevent damage to industrial equipment, it is necessary to detect overpressure in the equipment. This detection can be carried out by different types of sensors. A known type of sensor includes a membrane or diaphragm that deforms under the effect of the pressure increase on one of its faces and a device for measuring the deformation, which makes it possible to know the value of the pressure increase. Another means of detecting overpressure is to use a rupture disk. In particular, from the prior art, according to document US 5313194, a device is known that allows overpressure to be detected by rupture of a membrane or material screen. The device includes a rupture disk, which includes a conductive membrane and a housing, and the rupture disk is connected to a circuit that generates a signal by a wire. Therefore, in normal operation, the current passes through the rupture disk and flows from one wire to another. The rupture of the disk causes the circuit formed by the wire and the disk to be disconnected, and the overpressure is detected. Therefore, the device makes it possible to detect overpressure in industrial equipment simply and irreversibly.

[0003] However, although these devices can detect whether a predetermined pressure threshold is exceeded, they cannot detect sudden changes in pressure that could damage the equipment. In addition, their construction means that they will be damaged if placed in a corrosive medium or subjected to high temperatures. Summary of the invention

[0004] The present invention therefore aims in particular to provide a simple device allowing effective detection of sudden changes in pressure in a fluid.

[0005] Preferably, the device according to the invention is inexpensive and at the same time resistant to high temperatures and corrosive media.

[0006] To this end, the subject matter of the present invention comprises a pressure change detection device for detecting a sudden change in pressure in a fluid, the pressure change detection device comprising:

[0007] - a housing open at one end,

[0008] - a screen (un voile) closing the housing to create the chamber,

[0009] The screen is configured so that the internal pressure of the chamber approaches the external pressure when the external pressure of the chamber is substantially constant or slowly changing,

[0010] And the screen has mechanical properties that cause it to rupture when subjected to a predetermined difference between external pressure and internal pressure.

[0011] According to the present invention, a "sudden change" refers to a very rapid and unforeseeable change in pressure. Conversely, a "slow change" means that the change is not sudden. Such a non-sudden change occurs over a relatively long period of time or under conditions of change that are foreseen in advance and correspond to normal operation of the industrial equipment.

[0012] The pressure change detection device detects a sudden drop in pressure just as well as a sudden increase.

[0013] Therefore, the pressure change detection device has a simple design and can be adjusted to break when a predetermined pressure change occurs. In addition, the device detects pressure changes in an apparatus, yet the device does not require a fixture to fix it on the apparatus, but can simply be placed in the apparatus.

[0014] The following are other optional features of the device for detecting a sudden change in pressure in a fluid, which may be used alone or in combination:

[0015] - The screen is porous. The porosity of the screen allows the pressure inside and outside the chamber to be equalized. Its porosity can be chosen so as to equalize the pressure "slowly" while allowing rupture in the event of sudden changes, since the pressure will not be able to reach equilibrium quickly enough to avoid the pressure difference on both sides of the screen, causing it to rupture.

[0016] - The screen comprises graphite impregnated with a resin, preferably a phenolic resin. Graphite impregnated with phenolic resin has mechanical properties suitable for rupture under pressure differences. Furthermore, it is particularly suitable for use in corrosive media and at high temperatures. Finally, its porosity can be selected so that the pressure is slowly equalized.

[0017] - The screen consists only of graphite impregnated with a resin, preferably a phenolic resin. This further increases the ability of the device to be used in corrosive media.

[0018] - The device comprises a plurality of screens of mutually different thicknesses. The advantages of this feature will be understood from the examples described below.

[0019] - The screens are placed in order of increasing thickness, with the thinnest screens being the outermost. This feature enables the detection of increasingly large changes in pressure.

[0020] The device also comprises measuring means placed in the chamber. The measuring means placed in the chamber allow useful additional parameters such as pressure, temperature, time, etc. to be measured at or immediately after the screen rupture.

[0021] - The measuring device placed in the chamber is a timer. Thus, it is possible to know the exact moment when the sudden change in pressure that caused the screen to rupture occurred.

[0022] - The measuring device placed in the chamber is a pressure sensor. Therefore, in addition to the change value, the maximum pressure when the screen breaks can also be known;

[0023] Furthermore, the measuring device placed in the chamber can be disposable and triggered when the screen is ruptured. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention will be better understood by reading the following description which is given by way of example only and with reference to the accompanying drawings, in which:

[0025] [ Figure 1 ] Figure 1 is a schematic cross-sectional view of a device according to a first embodiment of the present invention;

[0026] [ Figure 2 ] Figure 2 yes Figure 1 A view of the device after the screen is broken;

[0027] [ Figure 3 ] Figure 3 is a schematic cross-sectional view of a device according to a third embodiment of the present invention, the device comprising a plurality of rupture screens, Figure 3 (a) shows the screen before rupture. Figure 3 (b) shows some screens after being broken and others still intact;

[0028] [ Figure 4 ] Figure 4 is a schematic cross-sectional view of a device according to a fourth embodiment of the present invention, the device comprising an additional sensor placed in the chamber;

[0029] [ Figure 5 ] Figure 5 An example of the internal and external pressure profiles for a particular screen is shown. DETAILED DESCRIPTION

[0030] Figure 1 and Figure 2 A pressure variation detection device according to a first embodiment is shown and is indicated by the general reference numeral 1 .

[0031] The device 1 according to the invention allows detecting sudden changes in pressure in a fluid or in other words a gaseous or liquid medium.Sudden changes in pressure of a fluid used in an industrial plant are liable to damage the industrial plant in which the device 1 is installed.

[0032] Figure 1An embodiment of the device 1 before rupture is shown. The device 1 comprises a cylindrical housing 20 open at both of its opposite ends and a rotating screen 10 closing the housing 20 at each of its open ends to create a chamber 30. The housing 20 holds the screen 10 and protects it. Figure 1 The cylindrical shape of the device 1 is an example, and the device 1 can adopt any shape that allows the housing 20 to be open at at least one end thereof and the screen 10 to close the end. For example, the housing 20 can have a total height of about 35 mm and an outer diameter of about 35 mm. Still by way of example, the inner diameter of the housing 20 can be about 15 mm.

[0033] In addition, the housing 20 can take different shapes so that it can be fixed in the medium in which the device 1 is used. In particular, holes and buckles can be added to allow the device 1 to be fixed to a part of the equipment in which the device is used, such as a wall. However, it should be understood that these devices are not necessary, and the device 1 can simply be placed in the equipment in which the pressure change is detected.

[0034] Figure 2 The device 1 is shown after the screen 10 has ruptured. The screen 10 ruptures when the fluid pressure outside the chamber 30 exceeds the pressure inside the chamber 30 by a predetermined value. Since the screen is constructed so that the pressure inside the chamber approaches the external pressure when the pressure outside the chamber is substantially stable or changes slowly, this pressure difference can only occur in the case of a sudden change in the pressure outside the chamber. This can be achieved by appropriate mechanical properties of the material constituting the screen 10.

[0035] The screen 10 is in fact constructed so that the pressure inside the chamber 30 is close to the external pressure when the pressure outside the chamber 30 is substantially stable or slowly changing. This property is obtained, for example, by a porous screen whose porosity is selected so that the pressure can be balanced between the inside and the outside of the chamber 30 under substantially stable pressure conditions in the equipment in which the device 1 is installed.

[0036] The porosity of the screen 10 is also small enough that the pressure inside and outside the chamber 30 does not immediately equalize when a sudden change in external pressure occurs. Thus, in this case, the screen 10 is subjected to a significant pressure difference, thereby inducing a force greater than its rupture threshold. The porosity is selected not only based on the pressure change that is desired to be detected, but also based on the medium in which the device 1 is placed.

[0037] In one embodiment, the adjustment of the rate of change of the rupture pressure detectable by the device 1 is achieved by selecting the thickness of the screen 10 so that its mechanical rupture occurs for a predetermined rate of change of pressure between the two faces of the screen.

[0038] The device 1 preferably has small dimensions. In this way, it is very suitable for placement in all types of equipment that are susceptible to pressure changes, in order to monitor the maximum speed of the pressure changes to which they are subjected. This is particularly useful for equipment that promises a mechanical guarantee to withstand sudden changes in pressure. Thus, the device 1 allows to determine whether damage to industrial equipment (such as a pipeline) is caused by a manufacturing defect of the pressurized equipment or by a sudden change in pressure caused by improper use of the equipment (such as in the case of water hammer or pump control errors). This is therefore particularly useful for defining liability in damage issues in order to apply for warranty or obtain insurance benefits.

[0039] Advantageously, the device 1 is made of a material that allows resistance to corrosion and to very high temperatures, which allows the device 1 to be used in most industrial installations. Preferably, the screen 10 comprises graphite impregnated with a resin, preferably a phenolic resin. In fact, impregnated graphite has corrosion resistance and high temperature resistance, which makes it particularly suitable for manufacturing the screen 10 of the device 1.

[0040] In a particular embodiment, the screen 10 consists only of graphite impregnated with resin. This makes it more resistant to corrosion and high temperatures.

[0041] For example, to produce a device for detecting sudden changes in pressure 1 that is sensitive to changes in pressure of 2 bar / minute, a rupture screen 10 made of impregnated graphite with a thickness of 0.9 mm and a diameter of 15 mm can be used. This thickness of 0.9 mm corresponds to a rupture of 1.7 bar at a standard temperature of 20° C., as confirmed by tests carried out on samples of the material used to produce the device.

[0042] Therefore, when the device 1 thus manufactured is subjected to a pressure variation outside the chamber 30 greater than 2 bar / minute, the pressure difference between the inside of the chamber 30 and the outside of the chamber 30 is greater than 1.7 bar and causes the screen 10 to rupture.

[0043] As information, in Figure 5 Examples of curves showing the effect of the rate at which the external pressure (or ambient pressure) changes on the pressure difference between the fluid below the screen 10 and the external fluid are shown in .

[0044] In other embodiments, the screen 10 is made of a metal that is resistant to corrosion and high temperatures of the medium in which the screen 10 is immersed during use.

[0045] The housing 20 may also comprise graphite or any other corrosion and high temperature resistant material, such as ceramic, or a metal or metal alloy, such as stainless steel or titanium.

[0046] Advantageously, the device 1 is placed at random in a space of the equipment in which it is subjected to the pressure variations of the method or the equipment it is checking.

[0047] It should be noted that unlike rupture disks often found on industrial equipment, the function of the device 1 is not to release pressure by creating an opening in the expansion space. Its function is to be used as a pressure indicator, for example in case of disputes over equipment warranty or for pressure checks in methods using liquids or gases.

[0048] The device 1 allows tracking of individual events. Since the device 1 is adjusted to a pressure change, it must be replaced after a rupture caused by this pressure change.

[0049] The rupture of the screen 10 of the device 1 is irreversible and very rapid. Due to the materials used, the response time of the device 1 makes it a very sensitive device to pressure peaks of very short duration, for example of the order of milliseconds.

[0050] When in use, the operator of the equipment in which the device 1 is placed customizes the frequency of visual inspection of the device. Therefore, the device 1 is regularly taken out of the equipment space in which it is placed for visual inspection. If there is no damage, it is put back in place. If the screen 10 is broken, the device 1 is replaced with a new one.

[0051] Figure 3 Another embodiment of the device 1 is shown. In this embodiment, the device 1 comprises a plurality of screens 10, 11, 12, 13 having mutually different thicknesses. Advantageously, the screens are positioned in order of thickness and the screens with the smallest thickness are located at the outermost sides of the chamber 30. This embodiment makes it possible to detect different pressure variations. This may be useful if it is known that in certain devices the damage varies depending on the pressure variation (speed of variation and pressure intensity).

[0052] Figure 4 A further embodiment of the device 1 is shown. In this embodiment, a measuring device 40 is located in the chamber 30. This measuring device 40 makes it possible to measure additional parameters when the screen 10 ruptures. The device 40 may be, for example, a timer which allows recording the precise moment when the rupture of the screen 10 occurs. The device 40 may also be a "conventional" pressure sensor which, in addition to the information provided by the device 1 about the sudden change in pressure, also provides information about the maximum pressure reached at the moment of the rupture of the screen 10. Figure 4 In the embodiment of (a), the measuring device 40 is a wireless device. Figure 4 In the embodiment of (b), the measuring device 40 is connected by a wire. The measuring device 40 can be a disposable type, performing its function only once when it first comes into contact with the fluid surrounding the device according to the invention. Its protection in the chamber makes it possible to measure only when the screen 10 is broken.

[0053] The present invention is not limited to the embodiments described and other embodiments will be apparent to those skilled in the art.

Claims

1. A pressure change detection device for detecting a sudden change in pressure in a fluid, the pressure change detection device (1) comprising: - a housing (20) open at one end, - a screen (10) closing said housing (20) to create a chamber (30), The screen (10) is porous, and the porosity of the screen (10) is selected so as to slowly balance the external pressure and the internal pressure of the chamber (30), so that: when the external pressure of the chamber (30) is basically stable or changes slowly, the internal pressure of the chamber (30) is close to the external pressure; and when the external pressure of the chamber (30) changes suddenly, the screen (10) ruptures when it is subjected to a predetermined difference between the external pressure and the internal pressure.

2. The pressure change detection device according to claim 1, wherein: The screen (10) comprises graphite impregnated with resin.

3. The pressure change detection device according to claim 2, wherein: The resin is a phenol resin.

4. The pressure change detection device according to claim 1, wherein: The screen (10) consists only of graphite impregnated with resin.

5. The pressure change detection device according to claim 4, wherein: The resin is a phenol resin.

6. The pressure change detection device according to any one of claims 1 to 5, comprising a plurality of screens (10, 11, 12, 13) having thicknesses different from each other.

7. The pressure change detection device according to claim 6, wherein: The plurality of screens (10, 11, 12, 13) are placed in order of increasing thickness, and the screen with the smallest thickness is located at the outermost side.

8. The pressure change detection device according to any one of claims 1 to 5, further comprising a measuring device (40) placed in the chamber (30).

9. The pressure change detection device according to claim 8, wherein: The measuring device (40) is a timer.

10. The pressure change detection device according to claim 8, wherein: The measuring device (40) is a pressure sensor.

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