Pressure regulator with outlet overpressure safety

Abstract

The invention relates to a regulator (2) for compressed gas comprising: a body (4) having a gas inlet (6), a gas outlet (8) and a gas passage (10) fluidly interconnecting the gas inlet (6) and the gas outlet (8); a pressure reducer (14) having a shut-off device and a movable component in the gas passage (10), the movable component being operatively connected to the shut-off device and defining, together with the body (4), a regulation chamber (14.6) downstream of the shut-off device; a pressure relief device (16) in the gas passage (10) downstream of the regulation chamber (14.6); and a flow restrictor (22) in the gas passage (10) upstream of the shut-off device, the flow restrictor (22) being sized to reduce the gas pressure at the gas outlet (8) below a maximum pressure value when the pressure relief device (16) is open and the shut-off device is open.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of regulators for compressed gases, and more particularly to regulators with pressure reducers, such as those installed on gas cylinders. BACKGROUND

[0002] It is common to install a regulator on a gas cylinder, which is designed to reduce the pressure of the gas in the cylinder, which can be up to about 200 bar, to a much lower pressure, for example a few bar, for use by an end-user installation. Such a regulator houses in its body a pressure reducer, which provides a shut-off device and a movable assembly, which is operatively connected to the shut-off device and delimits, with the body, a regulation chamber downstream of the shut-off device. Any pressure variation in the regulation chamber directly affects the position of the movable assembly, which in turn affects the opening of the shut-off device for compensating the pressure variation.

[0003] It is also common for a regulator installed on a gas cylinder to be provided with a pressure relief device, which is fluidly and operatively connected to the inlet pressure, i.e. the pressure in the cylinder, to avoid the pressure inside the cylinder from exceeding a predetermined level. The presence of such a pressure relief device largely depends on the type of gas stored in the cylinder and the application, i.e. the proximity conditions.

[0004] The published prior art patent document US2019 / 0277496A1 discloses a gas regulator, mainly for supplying a furnace burner with a fuel gas similar to natural gas, which is equipped with a diaphragm pressure reducer, a pressure relief device fluidly connected to the regulation chamber through the diaphragm, and an electrically operable flow restriction valve upstream of the pressure reducer. The purpose of this flow restriction valve is to limit the flow of gas output by the regulator when the end-user installation, for example the furnace burner, shows zero demand for gas. In fact, an electromagnetic shut-off valve is provided upstream of the furnace burner and downstream of the burner regulator. When this electromagnetic shut-off valve is closed, a parallel command signal is provided to the flow restriction valve in order to reduce the amount of gas fed to the burner regulator. The construction of the regulator according to this teaching is of interest for the safety provided to the end-user installation, for example the furnace burner and its regulator. However, it requires a command signal to operate, while many end-user installations do not include a shut-off valve that is electrically operated in the case of zero gas demand.

[0005] The prior art patent document EP3246781A1 discloses a gas regulator for hot air de-icing systems in turbojet engines, i.e. for lower pressure gas regulators. The regulator comprises a movable piston having a side hole which cooperates with a corresponding hole in the regulator body and forms a shut-off valve. The piston delimits with the body a regulation chamber which is fed with compressed gas from an external sensing line. The latter comprises a flow restrictor and a pressure relief device. The flow restrictor serves to fluidically separate the external sensing line from the regulation chamber. The pressure relief device acts only on the external sensing line, i.e. not on the outlet of the regulator, which means that if the piston is stuck in the open position, the outlet pressure will rise uncontrolled. SUMMARY

[0006] TECHNICAL PROBLEM

[0007] The technical problem addressed by the present invention is to overcome at least one of the drawbacks of the above-mentioned prior art. The technical problem addressed by the present invention is to provide a gas regulator with improved safety, in particular with respect to the outlet pressure, while maintaining a simple and reliable construction.

[0008] TECHNICAL SOLUTION

[0009] The present invention relates to a regulator for compressed gas, comprising: a body having a gas inlet, a gas outlet and a gas passage fluidically interconnecting said gas inlet and gas outlet; a pressure reducer having a shut-off device and a movable member in the gas passage, the movable member being operatively connected to the shut-off device and delimiting with the body a regulation chamber downstream of the shut-off device; a pressure relief device in the gas passage downstream of the regulation chamber; wherein the regulator further comprises: a flow restrictor in the gas passage upstream of the shut-off device, dimensioned to reduce the gas pressure at the gas outlet below a maximum pressure value when the pressure relief device is open and the shut-off device is open.

[0010] The flow restrictor is fixed and reduces the constant cross section.

[0011] Advantageously, the ratio of the cross section of the pressure relief device in the open state to the cross section of the flow restrictor is at least 5, preferably at least 10.

[0012] According to a preferred embodiment, the pressure reducer is configured to reduce the pressure at the gas outlet to a pressure reduction value, and the maximum pressure value is equal to or less than said pressure reduction value.

[0013] According to a preferred embodiment, the pressure relief device comprises a burst disk which bursts and opens completely when the pressure at the gas outlet exceeds a pressure relief value.

[0014] According to a preferred embodiment, the pressure relief value is greater than the pressure reduction value and the maximum pressure value.

[0015] According to a preferred embodiment, the regulator further comprises a check valve fluidically arranged downstream of the pressure relief device. The check valve is arranged to allow the gas to flow from the pressure relief device to the environment via the check valve.

[0016] According to a preferred embodiment, the flow restrictor is formed by a nozzle mounted on the body in the gas passage.

[0017] According to a preferred embodiment, the nozzle is an elongated cylindrical element having a calibrated through hole on the upstream side and a larger cavity on the downstream side, the cavity being configured for rotatable engagement with a tightening tool.

[0018] According to a preferred embodiment, the body exhibits a through hole forming part of the gas passage, the nozzle being screwed into said through hole.

[0019] According to a preferred embodiment, the through hole opens downstream into a bore housing a shut-off device of the pressure reducer, said shut-off device comprising a closing member comprising a poppet seated in the through hole and a stem extending from said poppet into the bore beyond the through hole, and an annular seat mounted adjacent to the through hole and cooperating with the poppet.

[0020] According to a preferred embodiment, the regulator further comprises a filtering element arranged directly upstream of the flow restrictor.

[0021] According to a preferred embodiment, the filtering element is seated in the through hole, retained on the upstream side by a shoulder of the through hole and on the downstream side by the nozzle.

[0022] According to a preferred embodiment, the filtering element is made of a porous rigid material forming a cylindrical wall having an upstream open end and a downstream end closed by a radial wall of said porous rigid material.

[0023] According to a preferred embodiment, the burst diaphragm has a periphery clamped between a shoulder formed in the body and a circular front face of the discharge connector screwed into said body.

[0024] According to a preferred embodiment, a cavity is provided on the downstream side of the burst diaphragm, the diameter of the cavity being at least 40%, preferably at least 50% of the diameter of the burst diaphragm at its periphery.

[0025] According to a preferred embodiment, the discharge connector houses a check valve.

[0026] Advantages of the invention

[0027] The invention is particularly interesting in that it provides reliable safety, even if the pressure reducer is blocked in the fully open position, the pressure at the gas outlet does not exceed the maximum pressure value. This is the result of a sufficient matching between the flow restrictor and the pressure relief device, taking into account the gas passage between the two. This solution is very reliable since it does not involve any moving parts and electronic commands.

[0028] The regulator according to the application can be set so that when the pressure relief device is open and the shut-off device is open, the maximum pressure value at the gas outlet is between 250 and 350 bars, while the pressure at the gas inlet is between 550 and 650 bars. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a sectional view of a regulator according to the application.

[0030] Figure 2 is a schematic layout of the regulator of Figure 1

[0031] Figure 3 is an enlarged view of the upper part of the regulator view in Figure 1

[0032] Figure 4 is an enlarged view of the flow restrictor and filter of the regulator view in Figure 1 and 3 DETAILED DESCRIPTION

[0033] Figure 1 is a longitudinal sectional view of a regulator according to the application.

[0034] The regulator 2 comprises a body 4 having a gas inlet, a gas outlet 8 and a gas channel 10 fluidly interconnecting the gas inlet and the gas outlet. The gas channel 10 comprises a first portion 10.1 from the gas inlet 6 to a shut-off valve 12, a second portion 10.2 from the shut-off valve 12 to a pressure reducer 14, a third portion 10.3 from the pressure reducer 14 to the gas outlet 8. The gas channel 10 further comprises a fourth portion 10.4 from the pressure reducer to a pressure relief device 16, parallel to the third portion 10.3. The gas channel 10 further comprises a fifth portion, not visible, between the first portion 10.1 close to the shut-off valve 12 and a refill valve 18, and a sixth portion 10.6 between the refill valve 18 and a refill port 20 closed by a removable refill plug.

[0035] The shut-off valve 12 is only partially visible in Figure 1 . It comprises a circular valve closing member provided with an annular seal contacting an annular seat formed in the body 4. These circular and annular elements are visible in the sectional view of Figure 1 . The shut-off valve 12 further comprises an actuation mechanism (not visible) for moving the closing member between an open position of the gas channel and a closed position of the gas channel, and vice versa.

[0036] ​​​In the cross-sectional portion 10.2 of the gas channel 10, between the shut-off valve 12 and the pressure reducer 14, a flow restrictor 22 is provided, and optionally also a filter 24 directly upstream of said flow restrictor. The flow restrictor 22 forms a channel for the gas with a reduced and calibrated cross-section. The dimensions of the reduced and calibrated cross-section are adapted such that, if the pressure reducer 14 is stuck in the open position, the pressure relief valve 16 will open, allowing a certain flow of gas to be discharged to the atmosphere, limiting the gas pressure directly downstream, i.e. at the gas outlet 8. In normal operation, i.e. when the pressure relief device 16 is not open and the pressure reducer 14 is functioning properly, the gas flow is substantially lower than in the case of a pressure reducer failure and overpressure as described above, which means that the pressure loss caused by the flow restrictor becomes negligible.

[0037] Figure 2 is Figure 1 a layout of the regulator shown, using common hydraulic symbols.

[0038] It can be observed from the gas inlet 6 that the gas inlet 8, the shut-off valve 12, the filter 24, the flow restrictor 22 and the pressure reducer 14 are visible. It can also be observed that the pressure relief valve 26 is provided and fluidically connected to the gas channel portion between the gas inlet 6 and the shut-off valve 12, i.e. is subjected to the inlet pressure, i.e. the pressure in the gas cylinder, and protects said gas cylinder from overpressure, for example in the event of a temperature increase due to a fire. It can also be observed that the pressure relief device 16, which is fluidically connected to the fourth portion 10.4 of the gas channel 10, is followed by a non-return valve 17, which is directly downstream of said pressure relief device.

[0039] Figure 3 is Figure 1 an enlarged view of the upper part of the regulator in

[0040] It can be observed that the pressure relief device 16 comprises a connector 16.1 having a threaded end 16.1.1 which engages with a corresponding thread 4.3 formed in a port 4.1 made in the body 4. The threaded end 16.1.1 comprises a front annular face 16.1.2 which presses the periphery of the burst diaphragm 16.2 against a shoulder 4.2 formed in the port 4.1 of the body 4. The threaded end 16.1.1 has a cavity 16.1.3 directly downstream of the burst diaphragm 16.2 so as to form a discharge passage for the gas and also to provide sufficient space for the diaphragm to deform and burst when the pressure at the gas outlet 8 reaches a predetermined maximum pressure value. The internal diameter of this cavity is at least 40%, and preferably 50%, of the diameter of the burst diaphragm 16.2, i.e. measured at its periphery. The connector 16.1 comprises a longitudinal discharge passage which extends from the cavity 16.1.3 to the outlet. A seat 16.1.4 is formed in the passage of the connector 16.1 against which a ball 17.1 is pushed by a spring 17.2 held by a retainer 17.3, for example in the form of a screw which is screwed into the thread of the passage. The ball 17.1 with the spring 17.2 and the retainer 17.3 forms with the seat 16.1.4 a safety device which prevents the gas from escaping from the pressure relief device 16 when the latter is not connected to the gas outlet 8. The ball 17.1 is held in the seat 16.1.4 by the spring 17.2 and the retainer 17.3. When the pressure relief device 16 is connected to the gas outlet 8, the ball 17.1 is pushed out of the seat 16.1.4 by the gas pressure and the gas can then escape from the pressure relief device 16 via the discharge passage. Figure 2 The check valve 17 is shown in Figure 3 and briefly described above in connection with this figure.

[0041] Furthermore, in Figure 3In this case, it can also be observed that the pressure reducer 14 comprises a shut-off device 14.1 / 14.2, essentially constituted by a closing member 14.1 and a seat 14.2, and a movable assembly 14.3-14.5, operatively connected to the shut-off device, for example to the closing member 14.1. The movable assembly comprises a movable element 14.3, pushed by a spring 14.4, and a flexible membrane 14.5, contacted by the movable element 14.3. The flexible membrane 14.5 delimits, together with the body 4, a regulation chamber 14.6, located in the gas passage formed in the body, downstream of the shut-off device 14.1 / 14.2. The closing member 14.1 comprises a poppet 14.1.1, which contacts the seat 14.2 on its upstream side. The closing member 14.1 also comprises a stem 14.1.2, which extends downstream from the poppet 14.1.1, through the seat 14.2, to the movable member 14.3. The stem 14.1.2 has a distal end, which is preferably attached to the movable member 14.3 in a rigid manner. The pressure reducer 14 also comprises a preset device 14.7, which exerts an elastic counterforce on the flexible membrane 14.5, for opening the shut-off device 14.1 / 14.2 and regulating the pressure in the regulation chamber 14.6, and thus the pressure reduction at the gas outlet 8. The preset device 14.7 essentially comprises a pusher, which contacts the flexible membrane 14.5, a spring, which acts on the pusher at one end, and an adjustable thrust at the opposite end of the spring. The adjustable thrust is, for example, manually operated. Once correctly operated, the preset device 14.7 exerts a counterforce on the flexible membrane 14.5, which is transmitted directly to the movable member 14.3, which is pushed by the spring 14.4 towards said flexible membrane. The counterforce balances the elastic force of the spring 14.4 and moves the movable member 14.3 towards the shut-off device 14.1 / 14.2, thus moving the poppet 14.1.1 away from the seat 14.2 and allowing the gas to flow into the regulation chamber 14.6 and, under pressure reduction, to the gas outlet 8. The working principle of the pressure reducer 14 is well known and does not need to be further detailed.

[0042] Still in Figure 3 In this case, the installation of the flow restrictor 22, the filter 24 and the shut-off device 14.1 / 14.2 of the pressure reducer 14 is described. The second portion 10.2 of the gas passage 10 is formed in the body 4 of the gas regulator 2, downstream of the first portion 10.1, and is delimited by the body 4 and by the closing member 14.1 of the shut-off device 14.1 / 14.2. The second portion 10.2 of the gas passage 10 is in fluid communication with the gas outlet 8. Figure 1) formed in the body 4. The through hole 4.4 opens downstream into a hole 4.5 formed in the body 4 and housing the shut-off device 14.1 / 14.2 of the pressure reducer 14. The filter 24 is inserted into the through hole 4.4 from the hole 4.5, then the flow restrictor 22 is inserted into said through hole 4.4 and fixed thereto by screwing. The hole 4.5 forms a shoulder near the end of the through hole 4.4 opening into said hole 4.5. The seat 14.2 of the shut-off device 14.1 / 14.2 is annular, with a first portion engaged into said through hole 4.4 and a second portion supported on the shoulder. The seat 14.2 is fixed in this position by a screw 14.8 which is threadedly fixed with the hole 4.5 and which shows the front face which presses the seat 14.2 against the shoulder. The screw 14.8 has a central longitudinal cavity through which the stem 14.1.2 of the closing element 14.1 extends. The body 4 shows a larger hole around the hole 4.5 which receives the screw 14.8 and receives the spring 14.4.

[0043] Figure 4 is Figure 1 and 3 Enlarged view of the flow restrictor and filter of the regulator view in

[0044] The filter element 24 is made of a porous rigid material forming a cylindrical wall, with an upstream open end and a downstream end closed by a radial wall of said porous rigid material. The through hole 4.4 formed in the body 4 has a shoulder 4.4.1 at the distal end against which the filter element 24 rests. The through hole 4.4 formed in the body 4 also has an internal thread 4.4.2 which engages with an external thread formed on the flow restrictor 22.

[0045] More particularly, the flow restrictor 22 is a nozzle 23 forming an elongated cylindrical element, with a calibrated through hole 23.1 on the upstream side and a larger cavity 23.2 on the downstream side, the cavity 23.2 having a non-circular annular surface 23.3 configured for rotatable engagement with a screwing tool.

[0046] The above-described structure of the flow restrictor 22 is particularly stable and robust, capable of supporting potentially large forces exerted by the gas at the gas inlet 8, particularly when the shut-off device 14.1 / 14.2 of the pressure reducer is blocked in the open position and the pressure relief device 16( Figures 1 to 3 ) is open so that a large flow of gas is flowing. In this case, the pressure on the downstream side of the flow restrictor is much lower than on the upstream side. The pressure difference between the upstream and downstream sides results in a force tending to push the nozzle forming the flow restrictor 22 out of the through hole 4.4. The cylindrical elongated shape of the nozzle provides sufficient length, i.e. number of turns, to the thread for properly supporting the resulting pushing force, while limiting this pushing force by reducing the cross section.

[0047] With reference toFigure 1 and Figure 3 In operation, before supplying gas to the end-user facility, pressure regulator 14 is preset to a given outlet pressure, causing its shut-off devices 14.1 / 14.2 to open. When shut-off valve 12 is actuated, gas flows from gas inlet 6 through pressure regulator 14 and regulating chamber 14.6 to gas outlet 8. Pressure regulator 14 ensures that the pressure at gas outlet 8 is maintained within a given pressure reduction range independent of the inlet pressure, until the inlet pressure drops below this range. If, for any reason, pressure regulator 14 malfunctions, causing the pressure at gas outlet 8 to increase above the pressure reduction range and reach the threshold level of pressure relief device 16, the latter will open, for example, by rupturing the diaphragm, resulting in the gas being essentially released. This higher gas release flow will create a considerable pressure loss at flow restrictor 22, ensuring that the pressure at gas outlet 8 does not exceed the given maximum pressure.

[0048] The pressure relief device 16 and the flow restrictor 22 are designed such that, once the pressure relief device is fully open and the pressure regulator's shut-off device is blocked in the fully open position, allowing gas to flow out, this will generate a pressure loss through the flow restrictor 22 sufficient to ensure that the pressure at gas outlet 8 does not exceed the maximum pressure value. If the pressure regulator's shut-off device is blocked in the partially open position, resulting in a lower gas flow rate than when the shut-off device is fully open, the pressure loss generated at the flow restrictor 22 will be even lower, meaning that the pressure directly downstream of the flow restrictor 22 will be higher than the maximum pressure value. However, in this case, the partially open shut-off device will generate a second pressure drop, similar to the flow restrictor 22, thus ensuring that the pressure at the gas outlet does not exceed the maximum pressure value.

[0049] For example, for a maximum pressure of approximately 600 bar at the gas inlet, the maximum pressure value can be set to approximately 300 bar. The pressure reduction value of the pressure regulator can also be approximately 300 bar. When in Figure 3 When considering the design of pressure reducer 14, especially preset device 14.7, it is clear that the pressure reducer in this particular example is specifically designed to output a fairly high pressure reduction, such as about 300 bar.

[0050] The cross-section of the flow restrictor cannot be defined or limited by an absolute value, as it largely depends on the maximum pressure value not exceeding and the gas discharge flow rate once the pressure relief device is opened. The gas discharge flow rate depends not only on the pressure relief device but also on the gas passage between the flow restrictor and the pressure relief device.

Claims

1. A regulator (2) for compressed gas, comprising: -A body (4) having a gas inlet (6), a gas outlet (8) and a gas passage (10) that fluidly interconnects the gas inlet (6) and the gas outlet (8); - A pressure reducer (14) having a shut-off device (14.1 / 14.2) and a movable assembly (14.3, 14.5) in a gas passage (10), the movable assembly being operatively connected to the shut-off device (14.1 / 14.2) and defining a regulating chamber (14.6) downstream of the shut-off device (14.1 / 14.2) together with the body (4); - Depressurization device (16) in the gas passage (10) downstream of the regulating chamber (14.6); The regulator (2) is characterized in that it further includes: - A flow restrictor (22) in the gas passage (10) upstream of the shut-off device (14.1 / 14.2) is sized to reduce the gas pressure at the gas outlet (8) below the maximum pressure value when the pressure relief device (16) is open and the shut-off device (14.1 / 14.2) is open.

2. The regulator (2) according to claim 1, wherein, The pressure reducer (14) is configured to reduce the pressure at the gas outlet (8) to a pressure reduction value, and the maximum pressure value is equal to or less than the pressure reduction value.

3. The regulator (2) according to any one of claims 1 and 2, wherein, The pressure relief device (16) includes a burst diaphragm (16.2), which bursts and fully opens when the pressure at the gas outlet (8) exceeds the pressure relief value.

4. The regulator (2) according to claim 3, wherein, The pressure relief value is greater than the pressure reduction value and the maximum pressure value.

5. The regulator (2) according to any one of claims 1 to 2 further includes a check valve (17) fluidly disposed downstream of the pressure relief device (16).

6. The regulator (2) according to any one of claims 1 to 2, wherein, The flow restrictor (22) is formed by a nozzle (23) installed on the body (4) in the gas passage (10).

7. The regulator (2) according to claim 6, wherein, The nozzle (23) is an elongated cylindrical element with a calibration through-hole (23.1) on the upstream side and a larger cavity (23.2, 23.3) on the downstream side, the cavity being configured to rotatably engage with a tightening tool.

8. The regulator (2) according to claim 7, wherein, The body (4) has a through hole (4.4) forming part (10.2) of the gas passage (10), and the nozzle (23) is screwed into the through hole (4.4).

9. The regulator (2) according to claim 8, wherein, The through hole (4.4) leads downstream to a hole (4.5) for receiving a shut-off device (14.1 / 14.2) for a pressure reducer (14). The shut-off device includes a shut-off member (14.1) comprising a lift valve (14.1.1) located in the through hole (4.4) and a rod (14.1.2) extending from the lift valve (14.1.1) out of the through hole (4.4) into the inlet hole (4.5), and an annular seat (14.2) mounted adjacent to the through hole (4.4) and cooperating with the lift valve (14.1.1).

10. The regulator (2) according to any one of claims 1 to 2 further includes a filter element (24) disposed directly upstream of the flow restrictor (22).

11. The regulator (2) according to claim 9, wherein, The filter element (24) is located in the through hole (4.4), held upstream by the shoulder (4.4.1) of the through hole (4.4) and downstream by the nozzle (23).

12. The regulator (2) according to claim 11, wherein, The filter element (24) is made of a porous rigid material and forms a cylindrical wall having an upstream open end and a downstream end closed by the radial wall of the porous rigid material.

13. The regulator (2) according to claim 4, wherein, The burst diaphragm (16.2) has a periphery sandwiched between a shoulder (4.2) formed in the body (4) and a circular front end (16.1.2) of a connector (16.1) screwed into the body (4).

14. The regulator (2) according to claim 13, wherein, The cavity (16.1.3) is located downstream of the rupture diaphragm (16.2), and the diameter of the cavity is at least 40% of the diameter of the rupture diaphragm (16.2) at its periphery.

15. The regulator (2) according to claim 5, wherein, The connector (16.1) according to any one of claims 13 and 14 accommodates the check valve (17).

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