REFILL DEVICE FOR A GAS CYLINDER

Technical field

[0001] The invention is directed to industrial gas, gas cylinders, equipment of gas cylinders and the refilling of such cylinders.

Background art

[0002] Prior art patent document published FR 2 878 312 A1 discloses a method for refilling a gas container such as a gas cylinder. The method provides to refill each container at one end of said container that is on an opposite side of the outlet. More specifically, the refill port comprises a check-valve that prevents the compressed gas to flow out. When refilling the container, a refill device is connected to the refill port of the container. The refill device comprises a body with a first port to be connected to the refill port of the container, and a second port to be connected to a refill gas source. A passage interconnects both ports. The device comprises also a slidable pin extending through the passage and the first port for opening the check- valve of the container. This feature allows a better control of the refill pressure. The device is however not adapted for the refilling of calibration gases that require a high level of purity.

[0003] Prior art patent document published FR 2 895 060 A1 discloses a refill device for calibration gas cylinder. The device comprises a body with a first port to be connected to the refill port of the calibration gas cylinder, a second port to be connected to a refill gas source, a third port to be connected to a vacuum pump and a fourth port to be connected to a liquid injection means. Only the third and fourth ports comprise a shut-off valve. The refill calibration gas source comprises its own shut-valve. The same applies to the gas cylinder to be refilled. Prior refilling, vacuum is applied to the inner volume of the gas cylinder. Afterwards, the liquid is injected in the cylinder and then the gas of the refill calibration gas source flows towards the cylinder so as to refill it. This device is interesting in that it permits to empty the gas cylinder by applying vacuum before refilling with gas. It is however designed to be connected to the outlet port of the gas cylinder, i.e. thereby requiring the manipulation of the shut-off valve of said cylinder.

Summary of invention

Technical Problem

[0004] The invention has for technical problem to provide a device for refilling a gas cylinder that overcomes at least one drawback of the above mentioned prior art. More specifically, the invention has for technical problem to provide a device for refilling a gas cylinder that is convenient to use, compatible to modern cylinders provided with a specific refill port, and that allows to keep a high level of purity of the refill gas.

Technical solution

[0005] The invention is directed to a refill device for a gas cylinder, comprising: a body with a first port for connecting to a refill port of the gas cylinder, and a second port for connecting to a refill gas source, and a passage fluidly interconnecting said first and second ports; a shut-off valve for shutting-off the passage; wherein the shut-off valve is located in the first port.

[0006] According to a preferred embodiment, the shut-off valve comprises a seat around the passage and a shutter slidably movable in the passage and configured for cooperating with said seat. The seat can be unitary with the body or, alternatively, attached to said body.

[0007] Advantageously, the first port comprises a cavity that opens out outwardly, the shutter being located in said cavity. The seat can be formed in the cavity.

[0008] According to a preferred embodiment, the shut-off valve further comprises a hand-wheel and a rod mechanically interconnecting said hand-wheel with the shutter, so that said hand-wheel can open and close the passage by moving the shutter.

[0009] According to a preferred embodiment, the rod is rigidly attached to the hand-wheel and the shutter, said hand-wheel being configured for moving said rod in rotation and translation while being rotated. The rod can be screwed into the shutter. [0010] According to a preferred embodiment, the device further comprises a mechanism interconnected between the rod and the hand-wheel, said mechanism converting a rotation of said hand-wheel exclusively into a translation of said rod.

[001 1] According to a preferred embodiment, the first port comprises a longitudinal axis, the shutter being movable in a direction that corresponds to said axis.

[0012] According to a preferred embodiment, the shutter comprises a front face oriented outwardly and a rear face opposed to said front face, said rear face being for cooperating with the seat for shutting-off the passage.

[0013] According to a preferred embodiment, the rear face of the shutter is conical and diverges in an outward direction of the first port.

[0014] According to a preferred embodiment, the rear face comprises a circular recess or a groove housing a gasket that is for contacting the seat.

[0015] According to a preferred embodiment, the shutter comprises on the front face a protrusion able to force-open a check-valve in the refill port of the gas cylinder when the shutter is distant from the seat.

[0016] According to a preferred embodiment, the body comprises a first portion with the first port and extending along a first direction and a second portion with the second port and extending along a second direction transversal to said first direction.

[0017] According to a preferred embodiment, the second portion of the body intersects the first portion at an intermediate position of said first portion.

[0018] According to a preferred embodiment, the second portion forms a gripping handle of said device.

[0019] According to a preferred embodiment, the hand-wheel is mounted at an end of the first portion of the body that this opposed to the first port.

[0020] The invention is also directed to a method for refilling a gas cylinder, comprising the following steps:

(a) connecting a refill port of the gas cylinder to a vacuum pump and to a refill gas source, by means of a refilling device;

(b) creating vacuum in the refilling device;

(c) refilling the gas cylinder with the source of gas; wherein the refilling device is according to the invention, step (b) is carried out while the shut-off valve of said device is opened and/or step (c) is carried out while said shut-off valve is opened.

[0021] An additional step (a ^* ) can be provided after step (a) and before step (b), consisting of supplying compressed gas to the refill device while the shut- off valve of said device is closed. Steps (a ^* ) and (b) can be carried out successively and iteratively. The compressed gas can be the refill gas or, preferably, an auxiliary gas like nitrogen. The purpose of this injection of gas followed by a suction, preferably in an iterative way, is to clean the passage of refill device. In step (b), the shut-off valve of said device is advantageously open in order to apply the vacuum not only to the gas passage between the first port and the shut-off valve but also the reduced volume between said valve and the refill port of the gas cylinder. If the shutter comprises on the front face a protrusion able to force-open a check-valve in the refill port of the gas cylinder, the shut-off valve is then in an intermediate position where it allows passage between the shutter and the seat while not force-opening the check-valve, i.e. keeping said check- valve closed.

Advantages of the invention

[0022] The invention is particularly interesting in that it provides a reduced volume between the shut-off valve and the refill port of the cylinder to be refilled. This volume reduction is advantageous in that it reduces the pollution of the gas to be refilled. This is particularly important for calibration gases. In addition, the shut-off valve permits to apply sequences of vacuum followed by supply of refill gas while the shut-off valve is closed, so as to "clean" the volume of the gas passage in the device. Also, the protrusion on the shutter of shut-off valve permits to force open the check-valve in the refill port of the cylinder, thereby allowing a better control of the refill flow.

Brief description of the drawings

[0023] Figure 1 is a sectional view of a refill device in accordance with a first embodiment of the invention.

[0024] Figure 2 is a side view of the refill device of figure 1. [0025] Figure 3 is a detail view of the shut-off valve of the device of figure 1 in the open position.

[0026] Figure 4 is a detail view of an alternative of the shut-off valve of the device of figure 1 in the closed position.

[0027] Figure 5 corresponds to figure 4 where the shut-off valve is in the open position.

[0028] Figure 6 is a sectional view of a refill device in accordance with a second embodiment of the invention.

Description of an embodiment

[0029] Figures 1 and 2 illustrate a device for refilling a gas cylinder, the device being in accordance with a first embodiment of the invention. Figure 1 is a sectional view whereas figure 2 is a side view.

[0030] The refill device 2 comprises a body 4 with a first portion 4 ¹ extending along a first main direction and a second portion 4 ² extending along a second main direction that is generally perpendicular to the first one. Both portions 4 ¹ and 4 ² can be assembled to each other, preferably by welding. The body 4 comprises on the first portion 4 ¹ a first port 6 to be connected to a refill port 12 of a gas cylinder (not represented). The body 4 comprises also a second port 8 on the second portion 4 ² , said port being to be connected to a source of refill gas, i.e. a container with pressurized gas for refilling the cylinder. As apparent in figure 1 , the body 4 comprises a passage 10 that fluidly interconnects the first and second ports 6 and 8.

[0031] Still with reference to figure 1 , a refill port 12 of a not represented gas cylinder is engaged with the first port 6 of the device 2. The refill port 12 comprises a check-valve 14 with a shutter 14 ¹ resting on a seat 14 ² against the resilient force of a spring 14 ³ . The check-valve 14 is oriented to block outflow and to allow inflow. For instance, the refill port 12 comprises an external thread that is engaged by a threaded sleeve-shaped nut 16 is in abutment against a shoulder portion of the port 6. The threaded engagement provides an engagement under pressure of the first port 6 against the refill port 12, providing a gas tight connection.

[0032] The first port 6 comprises a cavity 18 that opens out at the outlet of the port. The cavity 18 houses a shutter 20 that is slidable along the longitudinal axis of the port 6. The shutter 20 cooperates with a seat 22 for closing the passage. The seat 22 is formed around the passage 10 and is traversed by a rod 24 that mechanically interconnects the shutter 20 with a hand-wheel 26. This latter is arranged at an opposed end of the first portion 4 ¹ of the body 4. For instance, the rod 24 is rigidly attached to the hand-wheel. Also the hand-wheel 26 is in threaded engagement with first portion 4 ¹ of the body 4. Upon actuation by rotation the hand-wheel 24 moves axially. The same applies to the rod 24 and the shutter 20 which move then both in rotation and translation.

[0033] With reference to figures 1 and 2, the second portion 4 ² of the body 4 can comprise a knurled portion serving as gripping handle of the device 2.

[0034] In operation, the shut-off valve 20/22 can initially be at least partially opened. Vacuum can be applied through the second port 8 in order to empty the passage 10 from the second port 8 until the check-valve 14. Afterwards, the shut-off valve 20/22 can be closed and the passage can be filled with the refill gas or an auxiliary gas like nitrogen. To that end, the refill or auxiliary gas can be supplied to the device while the shut-off valve 20/22 is closed. After that, the refill or auxiliary gas supply can be shut-off and vacuum can then be applied followed by the supply of refill or auxiliary gas. This procedure can be repeated several times to clean the gas passage in the refill device. When applying vacuum, the shut-off valve can be opened to apply the vacuum also to the portion of gas passage between the shut-off valve and the refill port of the cylinder. After that, the shut-off valve 20/22 can be opened or kept opened for refilling the cylinder. The supply pressure of the refill gas opens the check-valve 14, thereby allowing the refill gas to flow into the cylinder. When the refill flow is stopped by shutting-off the refill gas supply, the check-valve 14 automatically closes. The refill device can then be dismounted from the cylinder.

[0035] As is apparent from the above, the fact of providing the shut-off valve 20/22 in the port 6 reduces significantly the dead volume between said valve and the check-valve of the cylinder. This reduces significantly the pollution of the gas to be refilled by the ambient air. This provides therefore a substantial advantage for calibration gases.

[0036] Figure 3 illustrates in detail the shut-off valve of the device of figure 1 in the open position. As apparent in figure 3, the shutter 20 comprises a protrusion 20 ¹ on its front face, i.e. on its face oriented towards the check- valve 14 of the refill port 12. This protrusion 20 ¹ is designed for contacting the shutter 14 ¹ of the check-valve 14 and for force-opening said check- valve. This can be useful during refilling for a better control of the refill flow by avoiding the refill flow having to urge the check-valve in the open position. This can also be useful for applying vacuum to the whole internal volume of the cylinder while applying vacuum to the passage 10 before supplying the refill gas.

[0037] During the above described "cleaning" procedure when refilling a gas cylinder, in view of the protrusion on the front face of the shutter, the shut- off valve is then in an intermediate position when applying vacuum after having applied an auxiliary or the refill compressed gas, where it allows passage between the shutter and the seat while not force-opening the check-valve, i.e. keeping said check-valve closed.

[0038] Still with reference to figure 3, we can observe that the shutter 20 comprises on its rear or internal face 20 ² , i.e. the face opposed to the front face with the protrusion, a circular recess or groove that houses a gasket 20 ³ that cooperates with the seat 22.

[0039] Figures 4 and 5 illustrate an alternative shut-off valve 20722 for the device of figures 1 to 3. Figure 4 illustrates the alternative shut-off valve 20722 in the closed position whereas figure 5 illustrates the valve in the open position. The shutter 20' of the alternative arrangement does not comprise a protrusion as in figures 1 and 3. Due to the absence of this protrusion, the shutter 20' cannot force open the check-valve 14 anymore. This means that during refilling the refill flow will have to force the opening of the check-valve.

[0040] Figure 6 illustrates a second embodiment of the refill device according to the invention. The reference numbers used for the first embodiment in figures 1 to 3 are used here for designating the same or corresponding elements, these numbers being however increased by 100 for differentiation purposes. It is referred to the description of these elements in relation with figures 1 to 3. Specific numbers comprised between 100 and 200 are used for designating specific elements.

[0041] The refill device 102 of figure 6 differs from the device of figures 1 to 3 in that it comprises a mechanism 128 that converts a rotation of the hand- wheel 126 exclusively in an axis translation of the rod 124. Indeed, the mechanism 128 comprises a slider 128 ¹ that is axially moved by a threaded engagement with a rotating sleeve 128 ² that supports the hand- wheel 126. Guiding pins 128 ³ are anchored in the first portion 104 ¹ of the body 104 and extend parallel to the main axis of said portion 104 ¹ . The slider 128 ¹ comprises holes receiving said pins so that the slider is prevented from rotating. The rod 124 is rigidly attached to the slider 128 ¹ .

[0042] Upon actuation of the hand-wheel 126, the sleeve 128 ² is rotated causing the axial movement of the slider 128 ¹ , resulting in an axial translation movement of the rod 124.

[0043] The remaining elements of the refill device 102 are similar to those of the device of figures 1 to 3. As mentioned above, it is referred to the description of these elements in relation with figures 1 to 3.