Surge protection valve for gas supply line

Abstract

A gas valve is disclosed that includes a valve body extending along an axis of the valve. The valve body has an internal valve seat. The outer surface of the valve body includes a breakable reduced diameter region located axially downstream of the valve seat. The valve gate is movable within the valve body along an axis between a valve open position and a valve closed position. The valve gate includes a central fluid passage extending along an axis and having a varying diameter along the axis. The sealing surface is located radially outward of the central fluid passage and engages the valve seat when the valve gate is in the valve closed position. A radially extending conduit extends from a fluid inlet on an outer surface of the valve gate to a fluid outlet leading to the central fluid passage. The valve gate includes another breakable reduced diameter region located axially downstream of the sealing surface.

Description

Background of the Invention Invention Field

[0001] This invention relates to a series-connected pressure surge protection device for gas supply pipelines, and particularly to a surge protection device for oxygen supply systems.

[0002] Description of related technologies

[0003] Surge protection devices can be installed in series between a gas supply tank or cylinder / bottle and a downstream pressure regulator. The downstream pressure regulator supplies gas to a process utilizing the gas at an appropriate pressure or flow rate. The surge protection device prevents damage to the downstream pressure regulator from sudden gas pressure surges from the gas cylinder when the pressure regulator is opened. Such pressure surges can cause the temperature in the supply line to rise due to adiabatic compression and can potentially promote ignition events, especially when the supplied gas is oxygen. An exemplary surge protection device is disclosed in U.S. Patent No. 4,172,468, issued October 30, 1979, the disclosure of which is incorporated herein by reference. However, known surge protection devices, if accidentally damaged, do not prevent the free release of pressurized gas from the attached cylinder. It is desirable to provide a surge protection device that both prevents pressure surges from affecting the downstream pressure regulator and prevents or significantly inhibits the free release of pressurized gas from the attached supply tank in the event of surge protection device failure or damage. Invention Overview

[0004] The following summary presents a simplified overview to provide a basic understanding of some aspects of the devices, systems, and / or methods discussed herein. This summary is not a comprehensive overview of the devices, systems, and / or methods discussed herein. It is not intended to identify key elements or define the scope of such devices, systems, and / or methods. The sole purpose is to present some concepts in a simplified form as an introduction to the more detailed descriptions that follow.

[0005] According to one aspect of the invention, a gas valve is provided, comprising a valve body extending along an axis of the gas valve. The valve body has an internal valve seat. An outer surface of the valve body includes a disconnectable diameter-reducing region located axially downstream of the internal valve seat. A gate is movable within the valve body along the axis between a valve open position and a valve closed position. The gate includes a central fluid passage extending along the axis and having a varying diameter along the axis. A sealing surface is located radially outside the central fluid passage and engages the valve seat when the gate is in the valve closed position. A radially extending conduit extends from a fluid inlet on the outer surface of the gate to a fluid outlet leading to the central fluid passage. The gate includes another disconnectable diameter-reducing region located axially downstream of the sealing surface.

[0006] According to another aspect of the invention, a gas valve is provided, comprising a valve body extending along an axis of the gas valve. The valve body has an internal valve seat. An outer surface of the valve body includes a disengageable annular groove located axially downstream of the internal valve seat. A gate is movable within the valve body along the axis between a valve open position and a valve closed position. The gate includes a central fluid passage extending along the axis and having a varying diameter along the axis. A sealing surface is located radially outside the central fluid passage and engages the internal valve seat when the gate is in the valve closed position. A radially extending conduit extends from a fluid inlet on the outer surface of the gate to a fluid outlet leading to the central fluid passage. The gate includes at least one disengageable groove located axially downstream of the sealing surface. When the gate is in the valve closed position, at least one disengageable groove is aligned with the disengageable annular groove of the valve body in a radial direction perpendicular to the axis.

[0007] According to another aspect of the invention, a gas valve is provided, comprising a valve body extending along an axis of the gas valve. The valve body has an internal valve seat. An outer surface of the valve body includes a first disconnectable diameter-reducing region located axially downstream of the internal valve seat. A gate is movable within the valve body along the axis between a valve open position and a valve closed position. The gate includes a central fluid passage extending along the axis and having a varying diameter along the axis. A sealing surface is located radially outside the central fluid passage and engages the internal valve seat when the gate is in the valve closed position. A radially extending conduit extends from a fluid inlet on the outer surface of the gate to a fluid outlet leading to the central fluid passage. The gate includes a second disconnectable diameter-reducing region on the outer surface of the gate located axially downstream of the sealing surface. When the gate is in the valve closed position, the second disconnectable diameter-reducing region is aligned with the first disconnectable diameter-reducing region in a radial direction perpendicular to the axis.

[0008] According to another aspect of the invention, a gas valve is provided, comprising a valve body extending along an axis of the gas valve. The valve body has an internal valve seat. An outer surface of the valve body includes a disengageable annular groove. A gate is movable within the valve body along the axis between a valve open position and a valve closed position. The gate includes a central fluid passage extending along the axis and having a varying diameter along the axis. A sealing surface is located radially outside the central fluid passage and engages the internal valve seat when the gate is in the valve closed position. A radially extending conduit extends from a fluid inlet on the outer surface of the gate to a fluid outlet leading to the central fluid passage. The gate includes at least one disengageable groove. When the gate is in the valve closed position, at least one disengageable groove is aligned with the disengageable annular groove of the valve body in a radial direction perpendicular to the axis. Attached Figure Description

[0009] After reading the following description with reference to the accompanying drawings, those skilled in the art will understand the above and other aspects of the invention, in which:

[0010] Figure 1 The gas supply system is shown;

[0011] Figure 2 It is a 3D diagram of a gas valve;

[0012] Figure 3 It is a 3D diagram of a gas valve;

[0013] Figure 4 This is a cross-sectional view of the gas valve;

[0014] Figure 5 This is a cross-sectional view of the gas valve; and

[0015] Figure 6 This is a 3D view of a part of a gas valve. Detailed Implementation

[0016] This invention relates to a series-connected pressure surge protection device for gas supply lines. The invention will now be described with reference to the accompanying drawings, wherein the same reference numerals throughout refer to the same elements. It will be understood that these different drawings are not necessarily drawn to scale with each other, nor within the given drawings, and in particular, the dimensions of the components are drawn arbitrarily for ease of understanding. In the following description, several specific details are set forth for purposes of explanation in order to provide a full understanding of the invention. However, it may be apparent that the invention can be practiced without these specific details. Furthermore, other embodiments of the invention are possible and the invention can be practiced and implemented in ways other than those described. The terminology and phrases used in describing the invention are adopted for the purpose of facilitating understanding of the invention and should not be considered limiting.

[0017] As used herein, “at least one,” “one or more,” and “and / or” are open-ended expressions that are both conjunction and disjunctive in operation. For example, each of the expressions “at least one of A, B, and C,” “at least one of A, B, or C,” “one or more of A, B, and C,” “one or more of A, B, or C,” and “A, B, and / or C” refers to A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together. Any disjunctive words or phrases that give two or more alternative terms, whether in the description of embodiments, claims, or drawings, should be understood to cover the possibility of including one of these terms, any of these terms, or all of the terms. For example, the phrase “A or B” should be understood to include the possibility of “A”, or “B,” or “A and B.”

[0018] Figure 1 A high-pressure gas canister or cylinder / bottle 12, for example, for supplying oxygen to welding systems or other systems, is shown, and this high-pressure gas canister or cylinder / bottle is well-known and includes a manually controlled canister valve 14. As is further well known, a manually controlled regulator or pressure reducing valve 16 is connected between the cylinder 12 and a supply hose 18 leading to a gas torch or other device (not shown). A surge-protected gas valve 10 or pressure damping valve according to the invention is connected in series between the canister valve 14 and the pressure regulator 16 via suitable fittings.

[0019] Surge protection device 10 is positioned in series between tank valve 14 and pressure regulator 16. High-pressure tanks or cylinders containing pure oxygen are prone to oxygen ignition due to their flammability. Surge protection device 10 is used to slowly introduce pressure from cylinder 12 into regulator 16 when the regulator is open, to prevent adiabatic compression and reduce the risk of flammable ignition. As will be discussed in more detail below, surge protection device 10 is a gas valve with a movable gate biased to the closed position by an internal spring and the upstream pressure of the gas in the cylinder. When regulator 16 is open, surge protection device 10 slowly allows pressure to build up downstream of the surge protection device (e.g., slowly introducing oxygen into the regulator body), and then the gate in the surge protection device fully opens due to the increased downstream pressure.

[0020] The surge protection device 10 also features a "quick-break safety" characteristic. Both the body of the surge protection device 10 and its gate have a disconnectable, reduced-diameter region or groove (e.g., a V-shaped notch) that provides a weak point or quick-break point designed to break upon strong impact. When breaking along the weak point, the gate in the surge protection device 10 automatically moves to the closed position due to upstream gas pressure from the cylinder 12. This prevents uncontrolled gas release from the cylinder 12.

[0021] Figure 2 and Figure 3 A perspective view of the surge protection device 10 is shown. Figure 2 The upstream end of the surge protection device 10 is shown, and Figure 3 The downstream end of the surge protection device is shown. The surge protection device 10 has a valve body 20 and an internal valve gate 22 movable within the valve body. The upstream end of the surge protection device 10 is attached to a cylinder (e.g., to a manually controlled tank valve 14). Figure 1For this purpose, the upstream end of surge protector 10 may include a standard tank coupling nut 22. The downstream end of valve body 20 may have external threads (not shown) to receive a coupling for connection to a downstream pressure / flow regulator. It should be understood that the upstream and downstream ends of valve body 20 are relative to the direction of fluid flow through surge protector 10. The upstream end of surge protector 10 includes a gas filter 24 that filters contaminants entrained in the gas from the tank. A C-clamp 26 or other suitable retention device is located directly downstream of gate 22 to retain the gate inside valve body 20. Valve body 20 may include an exhaust port 28 and a disconnectable diameter reduction region 30. The disconnectable diameter reduction region 30 provides a weak point at a specific axial location along valve body 20 to facilitate breakage at that axial location. As shown, the disconnectable diameter reduction region 30 may be an annular or circumferential groove, such as a V-shaped cut, surrounding the outer periphery of valve body 20. The breakable diameter reduction region 30 can have various cross-sectional shapes other than a V-shape, as long as the region promotes fracture at that axial location under a certain amount of force. In some embodiments, the breakable diameter reduction region 30 does not form a complete ring around the outer periphery of the valve body 20. For example, the breakable diameter reduction region 30 can extend partially around the outer periphery of the valve body 20 or take the form of a perforation with multiple diameter reduction segments.

[0022] Figure 4 and Figure 5 This is a cross-sectional view of surge protection device 10. Figure 4 Surge protection device 10 in the valve closed position is shown, and Figure 5 A surge protection device in the valve open position is shown. The valve body 20 and the valve gate 22 extend along axis 32, and the valve gate is movable along the axis within the valve body between the valve open position and the valve closed position.

[0023] Valve body 20 has an aperture extending along axis 32. This aperture may have a generally circular cross-section and a varying diameter along its length. Gate 22 is linearly movable within the aperture in valve body 20 along axis 32. Gate 22 has a central fluid passage 34 through which gas is supplied from a gas cylinder to a pressure / flow regulator. Gate 22 may include a head member 36 removably mounted on the upstream end of the gate. Head member 36 may have a form similar to a hexagonal cap nut and have internal threads to engage with external threads on the end of the gate. Head member 36 may include a truncated conical wall 38 extending circumferentially around the head member and facing downstream relative to the aperture in valve body 20. The truncated conical wall 38 provides a sealing surface located radially outside the central fluid passage 34 in the gate. When gate 22 is in the closed position, the truncated conical wall 38 engages and seals the internal valve seat 40 in valve body 20. The head member 36 is provided with a small-diameter confined passage 42, which is a flow restriction located along the central fluid channel 34. When the valve gate is in the closed position, this flow restriction prevents gas from flowing from the cylinder through the surge protection device 10 (e.g., through the central fluid channel 34). The small-diameter confined passage 42 is in fluid communication with the upstream end of the orifice in the valve body 20 and with the downstream end of the central fluid channel 34 in the valve gate 22. When the regulator is open, the small-diameter confined passage 42 slowly introduces pressure from the cylinder 12 into the regulator 16. Figure 1 In addition, it prevents gas from being rapidly released from the cylinder in the event of a surge protection device failure. It can be seen that the central fluid channel 34 in the valve gate 22 extends along the axis 32 and has a varying diameter along the axis. Specifically, the diameter of the central fluid channel 34 at the downstream end can be larger than the diameter at the upstream end, which has a small-diameter confined passage 42.

[0024] The orifice in the valve body 20 may have a shoulder having a circular inner periphery that provides a valve seat 40. The truncated conical wall 38 or sealing surface of the head member 36 engages the valve seat 40 in the direction of fluid flow through the orifice in the valve body 20. The gate 22 is biased downstream to normally close the orifice in the valve body 20. More specifically, the downstream end of the gate 22 has a shoulder 44, and the orifice in the valve body 20 has a shoulder 46 axially opposed to and spaced apart from the shoulder 44. The shoulders 44 and 46, together with the inner surface of the orifice in the valve body 20 and the outer surface of the gate 22, define a radial space extending circumferentially around the gate, and a compression or biasing spring 50 is received in this radial space, wherein opposite ends of the compression or biasing spring abut against the shoulders 44 and 46. Thus, the spring 50 biases the gate 22 downstream and correspondingly biases the sealing surface of the head member 36 to engage with the inner valve seat 40. The gas pressure from the upstream tank further pushes the truncated conical wall 38 of the head component 36 against the internal valve seat 40.

[0025] As in Figure 6 As best viewed, the gate 22 is provided with radially extending conduits 52 or passages of opposite diameter, located downstream of the head member 36 and its sealing surface. The radially extending conduits 52 extend from corresponding fluid inlets on the outer surface of the gate 22 to corresponding fluid outlets leading to the central fluid passage 34. When the gate is in the open position, the radially extending conduits 52 guide gas from the upstream portion of the orifice in the valve body 20 into the central fluid passage 34 in the gate 22. When the gate is in the open position... Figure 4 In the valve closed position, the radially extending conduit 52 does not receive gas flow from the orifice in the valve body 20 because the gas flow is blocked by the truncated conical wall 38 of the head member 36, which seals against the inner valve seat 40 in the orifice. When the gate 22 moves in the open direction (e.g., when downstream gas pressure overcomes the valve-closing bias force provided by the bias spring 50), the radially extending conduit 52 moves toward the inner valve seat 40 and is thus positioned to allow fluid flow to easily advance through it and into the central fluid passage 34. In the example embodiment shown in the figures, the radially extending conduit 52 can be considered to extend from a first fluid inlet on the outer surface of the gate 22 to a second fluid inlet on the outer surface of the gate, the second fluid inlet being spaced 180 degrees from the first fluid inlet. The radially extending conduit 52 can be a through-hole oriented perpendicular to the central fluid passage 34. The gate may include multiple (e.g., one, two, three, four, etc.) radially extending conduits 52 as needed, sufficient to guide the appropriate gas flow from the orifice in the valve body 20 to the central fluid passage 34 and to the downstream regulator.

[0026] The gate 22 may include a seal (such as an O-ring) to prevent gas leakage around the gate. To prevent any gas pressure build-up in the space between the seals (e.g., in the event of gas leakage through the seals), the valve body 20 may include one or more vent ports 28 communicating with the atmosphere through the valve body.

[0027] From the foregoing description, it should be understood that the gas flows through the valve in the left direction, such as... Figure 4 and Figure 5As shown. It should be further understood that the biasing spring 50 biases the gate 22 in the direction of fluid flow so that the sealing surface of the head member 36 normally remains against the inner valve seat 40, thereby closing the orifice in the valve body 20 to prevent gas from flowing around the head member and through the inner valve seat 40. When the gas supply valve is opened from the gas cylinder, the gas pressure suddenly surges into the upstream end of the orifice in the valve body 20, impacting the head member 36 and advantageously increasing the settling force of the truncated conical wall 38 on the valve seat 40, ensuring that no gas flows along the head member and across the valve seat. The confined passage 42 in the head member 36 discharges the gas from the gas cylinder through the head member to the central fluid passage 34 in the gate 22, and from there to the downstream pressure / flow regulator, so that pressure gradually builds up in the regulator, thereby preventing sudden pressurization of the regulator. When the pressure in the downstream regulator reaches a level where the impact is no longer significant—approximately 40% to 45% of the supply pressure—the force in the downstream working region of gate 22 will overcome the closing force provided by the bias spring 50 and the supply gas pressure acting on the head member 36. When the closing force is overcome in this way, gate 22 shifts to the right, as... Figure 5 As shown, this causes the truncated conical wall 38 to disengage from the internal valve seat 40, thus allowing the entire supply gas to flow through the head member 36 of the gate and into its radially extending conduit 52. The gate 22 will remain in the open position as long as the system is pressurized downstream and the downstream pressure generates a reaction force on the gate that overcomes the biasing force of the biasing spring 50. When the downstream pressure drops to a level that causes the reaction force to be less than the force of the biasing spring 50, the spring will close the surge valve 10 to prepare for a new operating cycle.

[0028] As described above, the surge protection device 10 features a "quick-break safety" characteristic. Both the valve body 20 and the gate 22 have a disconnectable diameter reduction region or groove (e.g., a V-shaped notch) that provides a weak point or quick-break point designed to break upon strong impact. When breaking along the weak point, the gate 22 automatically moves to the valve closed position due to upstream gas pressure from the gas cylinder. The weak point along the valve body 20 is provided by a disconnectable diameter reduction region 30. The corresponding weak point along the gate 22 is provided by another disconnectable diameter reduction region 54. In an example embodiment, the disconnectable diameter reduction region 54 may be a V-shaped notch groove along the outer surface of the gate, extending between radially extending conduits 52. Thus, the disconnectable diameter reduction region 54 may be located at the same axial position along the gate 22 as the radially extending conduits 52. The disconnectable diameter reduction region 54 may extend circumferentially around the outer surface of the gate 22 from a fluid inlet on the outer surface of the gate to a second fluid inlet on the outer surface of the gate. The disconnectable diameter reduction region 30 or disconnectable annular groove on valve body 20 is located axially downstream of inner valve seat 40. The disconnectable diameter reduction region 54 or disconnectable groove on gate 22 is located axially downstream of valve sealing surface provided by truncated conical wall 38 of head member 36. If valve body 20 and gate 22 break along weak points 30, 54, inner valve seat 40 and valve sealing surface provided by truncated conical wall 38 will remain attached to upstream gas cylinder and will close under pressure from the cylinder to prevent rapid, uncontrolled gas release. Gas will still be released slowly through restricted passage 42 in head member 36. Figure 4 As can be seen, when the gate 22 is in the closed position, the disengageable diameter reduction region 54 on the gate is aligned with the disengageable diameter reduction region 30 of the valve body 20 in a radial direction perpendicular to the axis 32. In the example embodiment, the weak points 30, 54 introduced on the surge protection device 10 are designed to break when a specific force or torque (e.g., 50 ft-lb) is applied. This force could be, for example, the result of a gas cylinder falling, or caused by an object falling or otherwise impacting the supply line between the cylinder and the downstream regulator.

[0029] It should be understood that this disclosure is by way of example, and various changes can be made by adding, modifying, or removing details without departing from the reasonable scope of the teaching contained herein. Therefore, the invention is not limited to the specific details of this disclosure unless so required by the appended claims.

Claims

1. A gas valve, comprising: A valve body extending along the axis of the gas valve, wherein the valve body has an internal valve seat, and wherein the outer surface of the valve body includes a disconnectable diameter-reducing region located axially downstream of the internal valve seat; A valve gate, movable along the axis within the valve body between a valve open position and a valve closed position, wherein the valve gate comprises: A central fluid channel, which extends along the axis and has a varying diameter along the axis. A sealing surface, located radially outside the central fluid passage, engages the inner valve seat when the valve gate is in the closed position. A radially extending conduit extends from a fluid inlet on the outer surface of the valve gate to a fluid outlet leading to the central fluid passage. The valve gate includes another disconnectable diameter-reduced region located axially downstream of the sealing surface.

2. The gas valve as claimed in claim 1, wherein, The radially extending conduit extends from the fluid inlet on the outer surface of the valve gate to another fluid inlet on the outer surface of the valve gate.

3. The gas valve as described in claim 2, wherein, The other disconnectable diameter-reducing region extends circumferentially around the outer surface of the gate from the fluid inlet on the outer surface of the gate to the other fluid inlet on the outer surface of the gate.

4. The gas valve of claim 1, further comprising a flow restrictor positioned along the central fluid channel.

5. The gas valve as described in claim 4, wherein, When the valve gate is in the valve closed position, the other disconnectable diameter reduction region is aligned with the disconnectable diameter reduction region of the valve body in a radial direction perpendicular to the axis.

6. A gas valve, comprising: A valve body extending along the axis of the gas valve, wherein the valve body has an internal valve seat, and wherein the outer surface of the valve body includes a disengageable annular groove located axially downstream of the internal valve seat. A valve gate, movable along the axis within the valve body between a valve open position and a valve closed position, wherein the valve gate comprises: A central fluid channel, which extends along the axis and has a varying diameter along the axis. A sealing surface, located radially outside the central fluid passage, engages the inner valve seat when the valve gate is in the closed position. A radially extending conduit extends from a fluid inlet on the outer surface of the valve gate to a fluid outlet leading to the central fluid passage. The valve gate includes at least one disconnectable groove located axially downstream of the sealing surface, and wherein, when the valve gate is in the valve closed position, the at least one disconnectable groove is aligned with the disconnectable annular groove of the valve body in a radial direction perpendicular to the axis.

7. The gas valve as claimed in claim 6, wherein, The radially extending conduit extends from the fluid inlet on the outer surface of the valve gate to another fluid inlet on the outer surface of the valve gate.

8. The gas valve as claimed in claim 7, wherein, The at least one detachable groove extends circumferentially around the outer surface of the gate from the fluid inlet on the outer surface of the gate to the other fluid inlet on the outer surface of the gate.

9. The gas valve of claim 6, further comprising a flow restrictor positioned along the central fluid channel.

10. The gas valve as claimed in claim 9, wherein, When the valve gate is in the valve closed position, the at least one disengageable groove is aligned with the disengageable annular groove of the valve body in a radial direction perpendicular to the axis.

11. A gas valve, comprising: A valve body extending along the axis of the gas valve, wherein the valve body has an internal valve seat, and wherein the outer surface of the valve body includes a first disconnectable diameter-reducing region located axially downstream of the internal valve seat; A valve gate, movable along the axis within the valve body between a valve open position and a valve closed position, wherein the valve gate comprises: A central fluid channel, which extends along the axis and has a varying diameter along the axis. A sealing surface, located radially outside the central fluid passage, engages the inner valve seat when the valve gate is in the closed position. A radially extending conduit extends from a fluid inlet on the outer surface of the valve gate to a fluid outlet leading to the central fluid passage. The valve gate includes a second disconnectable diameter reduction region on the outer surface of the valve gate located axially downstream of the sealing surface, and wherein, when the valve gate is in the valve closed position, the second disconnectable diameter reduction region is aligned with the first disconnectable diameter reduction region in a radial direction perpendicular to the axis.

12. The gas valve as claimed in claim 11, wherein, The radially extending conduit extends from the fluid inlet on the outer surface of the valve gate to another fluid inlet on the outer surface of the valve gate.

13. The gas valve as claimed in claim 12, wherein, The second disconnectable diameter-reducing region extends circumferentially around the outer surface of the valve gate from the fluid inlet on the outer surface of the valve gate to the other fluid inlet on the outer surface of the valve gate.

14. The gas valve of claim 11, further comprising a flow restrictor positioned along the central fluid channel.

15. A gas valve, comprising: A valve body extending along the axis of the gas valve, wherein the valve body has an internal valve seat, and wherein the outer surface of the valve body includes a disengageable annular groove. A valve gate, movable along the axis within the valve body between a valve open position and a valve closed position, wherein the valve gate comprises: A central fluid channel, which extends along the axis and has a varying diameter along the axis. A sealing surface, located radially outside the central fluid passage, engages the inner valve seat when the valve gate is in the closed position. A radially extending conduit extends from a fluid inlet on the outer surface of the valve gate to a fluid outlet leading to the central fluid passage. The valve gate includes at least one disconnectable groove, and when the valve gate is in the valve closed position, the at least one disconnectable groove is aligned with the disconnectable annular groove of the valve body in a radial direction perpendicular to the axis.

16. The gas valve as claimed in claim 15, wherein, The radially extending conduit extends from the fluid inlet on the outer surface of the valve gate to another fluid inlet on the outer surface of the valve gate.

17. The gas valve as claimed in claim 16, wherein, The at least one detachable groove extends circumferentially around the outer surface of the gate from the fluid inlet on the outer surface of the gate to the other fluid inlet on the outer surface of the gate.

18. The gas valve of claim 15, further comprising a flow restrictor positioned along the central fluid channel.

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