GAS SAFETY VALVE Field of the Invention This invention relates to an apparatus which is useful in significantly increasing the safety of gas lines and gas equipment. More particularly, this invention relates to a two- way safety valve which prevents the accidental escape of gas when a high pressure gas line leaks or is ruptured Background of the Invention Relatively low pressure inflammable gas is utilized for a great number of applications. For example, metal bottles containing propane are often used to provide fuel for torches, gas barbecues, stoves and gas appliances such as might be found in a typical recreation vehicle. In many areas of the continent, natural gas is piped under pressure from a gas utility to homes for use in cooking, heating and the like. Typically, such gas pressures will run in the vicinity of between about 60 psig and 300 psig. In utilizing gas received through a pressure gas line from a gas source, it is typically passed through a pressure regulator before being transmitted to the point of consumption.

It is a relatively common occurrence for gas lines between the regulator and the point of consumption to become ruptured, or for the valves or lines in such a position to leak.

Such rupture may result from accidental blows to the line or valves, or simply from improper installation. Leakage can also result from a faulty pressure regulator. Any unwanted or undetected leakage can result in an uncontrolled flow of inflammable gas thereby producing a hazardous situation. This is particularly true if the gas leak or flow is proximate to the point of consumption. There is usually a pilot light or flame at the consumption point and leaked or undetected stray gas can cause dangerous uncontrolled fires or explosions.

Many devices have been designed and disclosed in the past for minimizing the danger which may result from accidental leakage of inflammable gas such as referred to in the applicant's United States Patent No. 4,590, 962.

Summary of the Invention Because of the potential hazards associated with the use of high pressure inflammable gas, and the demand of the public that such gas must be completely safe to use, there has been a longstanding need to have a gas safety valve which is relatively simple to construct and reliable in operation, which provides complete cut-off of a gas flow in either direction upon loss of pressure at either the inlet or outlet, and which can be reset without detaching the gas fuse from a gas bottle, or other source of gas. To address this, the present invention is a safety valve which offers three safety features. It provides complete shut-off of high pressure gaseous fuel from the tank to the regulator, complete shut-off of low pressure fuel from the regulator to the appliance, and complete shut-off of upstream flow of gaseous fuel into an empty bottle, thereby eliminating a potentially dangerous situation.

The gas safety valve includes a housing having a valve chamber which has therein a gas inlet and a gas outlet which communicate respectively with an inlet and outlet end of the valve chamber. Valve means are disposed in the housing for allowing a gas flow from the inlet to the outlet when the valve means is in an open position. The valve means prevents gas flow when in the closed position involving either the inlet or the outlet. The valve means is disposed in the valve chamber and is movable therein in response to a pressure differential in either direction between the inlet and the outlet of the valve chamber. The gas safety valve includes resilient means extending between the housing and valve means for urging the valve means into the open position. The resilient means allows the valve means to reversibly move to the closed position when the pressure differential between the inlet and outlet ends of the valve chamber become sufficiently high to overcome the resilient means.

The gas safety valve may include a release valve disposed in a bleed passage from the inlet to the exterior of the housing, so as to release gas from the inlet end of the valve chamber when the valve means is in an inlet closed position. In one embodiment the valve means comprises a rigid shuttle valve such as a piston slidably mounted in the valve chamber.

The release valve may be a manually operable check valve.

The invention is directed to a safety valve for use in a pressurized gas line. The invention includes a housing having a valve chamber, a gas inlet communicating with an inlet at one location in the valve chamber, and a gas outlet communicating with an outlet at another location in the valve chamber. A valve means is disposed in the valve chamber for allowing gas to flow from the inlet to the outlet when the valve means is disposed intermediate the inlet and outlet and for preventing gas flow from the inlet to the outlet when the valve means abuts the outlet, and for preventing reverse gas flow from the outlet to the inlet when the valve means abuts the inlet. The valve means has a gas conduit therethrough which causes gas passing through the conduit to change direction sharply before exiting the valve mean.

Resilient means extends between the outlet of the valve chamber and the outlet side of the valve means for urging said valve means into an intermediate open equilibrium position in the valve chamber, but allowing the valve means to reversibly move to a closed position against the outlet when the pressure differential between the inlet and outlet of the valve chamber becomes sufficiently high to overcome the resistance of the resilient means, the resilient means also permitting the valve means to abut the inlet when a reverse differential in pressure exists in the valve chamber.

In the safety valve, the valve chamber may be of a hollow cylindrical configuration. The valve means may be a piston having a first end facing the inlet of the valve chamber and an opposite end facing the outlet of the valve chamber. The piston fits snugly against the walls of the valve chamber and is free to move from an inlet closed position, wherein the inlet facing end of the piston blocks the inlet, to an outlet closed position wherein the outlet facing end of the piston blocks the outlet. The piston has, between the inlet facing end and the outlet facing end a hollowed-out portion which forms part of the tortuous gas

conduit passing through the piston. The hollowed-out portion may extend around the circumference of the piston. The conduit may pass through the portion of the piston on the inlet side of the hollowed-out area, then through the hollowed-out portion, and through the portion of the piston on the outlet side of the hollowed-out area.

The inlet end is adapted for connection to a source of pressurized gas. An inlet opening communicates with the chamber for permitting gas flow thereto. The outlet end is adapted for connection to a gas distributor. An outlet opening communicates with the chamber for permitting gas flow therefrom.

The valve means is adapted for longitudinal displacement between the inlet opening and the outlet opening in response to the gas pressure differential between the openings. This is accomplished by the valve means including first and second annular parallel disks, each having top and bottom surfaces. A centrally disposed axial shaft is positioned between and separating the parallel disks. It has a diameter substantially less than the diameter of either of the disks. The axial shaft and the disks form therebetween an annular recess. The disks have an outer diameter substantially equal to the diameter of the chamber for providing sliding sealing engagement with the wall of the chamber.

The first disk includes a first frustoconical sealing means for sealing the inlet opening and thereby preventing gas flow to the chamber when the pressure differential between the openings is less than a first preselected level so that the valve means is displaced to and seals the inlet opening. The second disk includes a second frustoconical sealing means for sealing the outlet opening and thereby preventing gas flow from the chamber when the pressure differential between the openings exceed a second preselected level and thereby causes the valve means to be displaced to and seal the outlet opening. The first and second frustoconical sealing means are oppositely co-axially disposed. The resilient means engages the valve means and the outlet end for biasing the valve means for longitudinal displacement toward the inlet so that the pressure differential between the openings must exceed the first

preselected level to cause the valve means to be displaced out of sealing engagement with the inlet opening and to thereby permit gas flow to the chamber.

At least a first passageway in the first disk axially extends from its top surface to its bottom surface and opens into the annular recess for permitting gas flow fi-om the inlet opening to the annular recess when the valve means is displaced away from the inlet end. At least a first passageway in the second disk axially extends from its top surface to its bottom surface and opens into the chamber permitting gas flow from the annular recess into the chamber when the valve means is displaced away from the outlet end. The first disk passageway and the second disk passageway may be displaced axially from each other at least 90 degrees. to permit a shift of the gas flow laterally in the annular recess as it passes from the first disk passageway to the second disk passageway.

Brief Description of the Drawings Figure 1 is, in perspective view, the safety valve of the present invention installed on a gas tank.

Figure 2 is, in exploded view, the safety valve of Figure 1.

Figure 2a is, in partially cut away sectional view, the dash pot in its inlet closed position in the safety valve of the present invention.

Figure 3 is a cross sectional view through the exploded view of Figure 2.

Figure 4 is, in partially sectioned exploded view, the pressure release valve of Figure 3.

Figure 5 is, in enlarged view, the dash pot of Figure 3.

Figure 6 is, in enlarged partially cut away view, the conical seat of the outlet of Figure 3.

Figure 7 is a sectional view along line 7-7 in Figure 5.

Figure 7a is a sectional view along line 7a-7a in Figure 5.

Detailed Description of Embodiments of the Invention As seen in Figures 1-3, gas safety valve I is formed of two mating components, namely a housing and a fitting. Housing 2 has an inlet end 3. Fitting 4 has an outlet end 5.

The housing 2 may have a generally elongated hexagonal shape except for the inlet end 3 which is circular, having male threads 6 around the exterior thereof. Housing 2 and fitting 4 in combination form a valve chamber 7. Valve chamber 7 is in fluid communication with an inlet conduit or inlet 8 formed in housing 2 and extending through inlet end 3, and an outlet conduit or outlet 9 formed in fitting 4.

A portion of the inside surface of the valve chamber 7 at the outlet 9 is provided with standard female threads 10. The exterior inlet end 3 is provided with standard male threads 6 which are adapted to be received gas-tight in the mating female threads of a standard gas connection or line such as that used on a commercial propane or butane tank or cylinder la so as to provide a gas flow in direction A. The inlet 8 extends axially through the inlet end 3 of the housing 2 and connects the exterior of the inlet end 3 in fluid communication with the valve chamber 7.

The outlet end of housing 2, by being provided with female threads 10, is adapted to receive the corresponding male threads 11 of fitting 4. Fitting 4 may also be hexagonally shaped and has a female threaded surface 12 which is adapted to receive a

standard gas line fitting (not shown) such as is used on a regulator or a propane stove or the like. The female threads 12 correspond in pitch with male threads 6 of housing 2. The outlet 9 has a frustoconical portion 13 extending from the outlet 9 into the area enclosed by threads 12.

The opposite end of outlet 9 communicates with the outlet end of valve chamber 7. An O-ring 27 fitting in a recess in fitting 4 ensures that a tight gas seal is obtained between fitting 4 and housing 2.

As can be better seen in Figure 5, a two-way piston, shuttle, or dash pot 14 fits within valve chamber 7. The side wall 15 of chamber 7 is cylindrical. Likewise, the lateral exterior surface 16 of dash pot 14 is cylindrical so that dash pot 14 fits snugly within cylindrical walls 15 and can slide in direction B backwardly and forwardly left-to-right and vice versa as seen in Figure 3 a short distance inside valve chamber 7.

The dash pot 14, being slidably disposed within valve chamber 7, will slide therein in response to a pressure differential between the inlet 8 and outlet 9 of the valve chamber 7. The dash pot 14 can slide in direction B between an inlet closed position as shown in Figure 2a, in which the dash pot 14 is abutted against inlet 8, and an outlet closed position wherein dash pot 14 abuts the opening to outlet 9. In the inlet closed position which occurs when there is a back pressure between inlet 8 and outlet 9, tapered plug or nose 20 mates into the downstream end of inlet 8 so as to prevent gas flow out through the inlet 8 in a direction opposite to direction A. An O-ring 20a mounted in a groove around the base of plug 20 provides a gas tight seal between dash pot 14 and inlet 8. In the outlet closed position, in which the dash pot 14 abuts the outlet 9, a frustoconical plug 18, mounted on dash pot 14 so as to be oppositely disposed relative to plug 20 and co-axial therewith along axis of symmetry C, mates into a corresponding conical seat 9a in outlet 9 so that no gas can flow from the valve chamber 7 through outlet 9. An O-ring 18a mounted in a groove medially along furstoconical plug 18 provides a gas tight seal between dash pot 14 and outlet 9. 0-rings 18a and 20a may be of the type available on the market under the trademark Viton, for example a Viton O-ring 01 1. The conical angle a of plug 18 may be in the range of generally sixty degrees and should match an equal angle ß in conical seat 9a.

Compression coil spring 17 is disposed in the valve chamber 7 so as to abut outlet 9 at one end and dash pot 14 at the opposite end. The spring 17 is a compression coil spring type so as to resiliently bias or urge the dash pot 14 into an open or equilibrium position approximately mid-way along chamber 7 between inlet 8 and outlet 9. In this position, gas can flow from inlet 8 through to outlet 9 along a sinuous or tortuous flow path through the dash pot as hereinafter better described. However, the compression strength of the spring 17 is selected so as to allow the dash pot 14 to reversibly move to the outlet closed position thereby blocking outlet 9 when the pressure differential between inlet 8 and outlet 9 of the valve chamber 7 becomes sufficiently high. The expression"sufficiently high"is to be interpreted as meaning that the pressure differential between inlet 8 and outlet 9 becomes sufficiently great so as to cause the dash pot 14 to move in a direction toward the outlet 9 and compress the spring 17 until the dash pot 14 reaches the outlet c) osed position. The compression strength of the spring 17 can be varied according to the capacity of the gas safety valve that is required for any given situation, for example, home use, industrial use, or camper use.

Thus, gas safety valve 1 has the capacity to prevent gas flow in either direction along axis C. Gas flow in direction H from the inlet 8 to the outlet 9, as described above, is prevented when dash pot 14 overcomes the resistance of spring 17 and abuts outlet 9. In my previous design which is the subject of United States Patent No. 4,590, 962, gas sealing capacity was enhanced by an O-ring resting in a groove around the planar face circumferentially surrounding outlet 9. It was found that it was difficult to retain O-ring 18 within that groove without machining the groove with an annular retaining lip to hold the O- ring in the groove. This as it turns out was prohibitive in attempts at mass-production while maintaining the required close tolerances. Consequently there was a need for the improvement, which is the subject of the present invention, wherein the 0-ring is moved from a planar face around outlet 9 to a new frustoconical plug 18 formed on the dash pot itself.

The construction of dash pot 14 is illustrated in detail in Figure 5, which represents a side section view, and Figure 7 and 7a, which represents sectional elevation views of dash pot 14. Viewed from the side, dash pot 14 is constructed to have roughly an"H"

shape. The mass of dash pot 14 can be varied to satisfy various capacity and pressure response requirements for the safety valve 1. For small applications, the mass of dash pot 14 would be reduced by increasing the width of annular recess 21, or machining away material. For higher capacity applications requiring a heavier dash pot 14, recess 21 would be relatively narrow, and more mass might be present in the downstream end, for example in plug 18. The dash pot 14 illustrated in Figure 5 would be typical for the ordinary home gas consumption environment wherein gas pressures would be in the order of 250 psig, and gas flows would be such as to result in for example 80,000 BTU's per hour.

The circumference of the dash pot 14 fits snugly against the cylindrical wall of the valve chamber 7 and is generally gas-tight. Thus, the dash pot 14 is constructed so that it has small openings therethrough, which permit gas to pass through the dash pot 14 when the dash pot 14 is in its equilibrium position mid-way between inlet 8 and outlet 9. The forward or upstream disc 23 (or left leg of the"H"as seen from the side in Figure 5) has machined therethrough at least one small opening or aperture 24. If need be, two openings 24, illustrated to be oppositely disposed on disc 23, can be provided. The diameter of apertures 24 are selected to suit the gas consumption requirement for the particular application in which the gas safety valve 1 is being installed. The flow of gas through apertures 24 balances the compression strength of spring 17, so that when the gas safety valve I is in the equilibrium position, that is, mid-way between inlet 8 and outlet 9, there is a balance. A sudden upset of the balance of pressure, from either side, will then either move the dash pot 14 to an outlet closed position abutting outlet 9, or an upstream, that is inlet, closed position, wherein the dash pot 14 abuts inlet 8. The safety valve I is therefore capable of stopping the flow of gas when there is a drop in gas pressure in either the upstream or downstream side of the safety valve.

As illustrated in Figure 7, two small openings 24 may be machined in the primary piston head wall formed by disc 23. One or more similar openings or apertures 25 are machined in the secondary wall formed by corresponding parallel disc 26. Openings or apertures 25 in disc 26 may be of the same diameter as openings 24. In order to increase the sensitivity of the dash pot 14 to changes in pressure differential, the positions of openings 24

in the disc 23 may be offset (for example by 90 degrees) relative to openings 25 in disc 26.

While the applicant does not wish to be bound to any particular physical theory, it is thought that by having the gas first flow through opening or openings 24 (such as the oppositely spaced pair illustrated), and then forcing the flow to turn or twist through the manifold formed by annular recess 21 in order to flow through opening or openings 25 (such as the oppositely spaced pair illustrated), a slight torque force may be imparted on the dash pot 14, which may cause the dash pot 14 to be more sensitive to gas pressure changes. This action may occur regardless of the direction in which the gas is flowing through the safety valve 1. This may give high sensitivity on the low pressure portion of the system existing from the regulator to the appliance. Complete shut-off may thus be provided even in instances where the remaining pressure in the bottle is only 9 or 10 ounces.

A filter 28 may be mounted in the upstream end of inlet 8. Filter 28 may be of stainless steel mesh having a 140 micron gauge. Filter 28 prevents sold matter from entering the gas safety valve 1. inlet 8 in inlet end 3 has a bleed passage 29 which has disposed in it at its other end, a pressure release valve 30 in the form of a manually operable check valve.

As better seen in Figure 4, a press-button 31 threadably mates with an elongate piston 32 so as to slidably mount the resulting manually operable plunger in collar 33 for sliding along axis D. Collar 33 threadably mounts into an expanded end 29a of bleed passage 29 so as to maintain piston 32 in the expanded end resting against spring 34 also mounted within the expanded end. Depressing button 30 against the side of housing 2 drives piston 32 into the expanded end 29a against the return biasing force of spring 34 so as to unseat O-ring 35 on piston 32 from its sealing engagement against the underside of collar 33. This allows pressurized gas in inlet 8 and upstream of dash pot 14 to escape through bleed passage 29, past piston 32 loosely journalled through collar 33.

All main components of the gas safety valve described are made from non- corrosive metals such as brass and stainless steel. This provides virtually indefinite life. The

inside surface of the valve chamber 7 has a fine finish which enables the dash pot 14 to smoothly slide therein without undue friction. The 0-rings sealing all connection points may be made from a suitable elastic material such as made by Viton or such as Nitrille (trade mark) or the like as would be known to one skilled in the art.

To use the gas safety valve 1, the inlet suitable end 3 is screwed into the female standard coupling of a source of pressurized gas, typically gas with a pressure in the vicinity of 60 psi to 300 psi. The female threaded portion 12 is then connected by means of suitable approved gas coupling to a standard pressure regulator which in turn is connected to the point of consumption of the gas. Consumption is usually in the form of an open flame. Under normal operation, gas will be free to flow from the source of pressurized gas, progressively through the inlet 3, the inlet 8 of the valve chamber 7, apertures 24 and 26 in the dash pot 14, the outlet 9 of the valve chamber 7, and finally out of outlet end 5 to the pressure regulator.

However, if pressure at the outlet 5 drops beyond a level which corresponds to the compression force on spring 17, such as would occur upon rupture in any lines receiving gas from the outlet 5, a pressure imbalance develops because the rate of gas flow through the apertures 24 and 25 is fixed and the pressure at the inlet end 3 of the valve chamber 7 remains virtually constant. This imbalance results in a sufficient pressure differential on the upstream side of the dash pot 14 which thereby causes the dash pot 14 to overcome the force of spring 17 and move the dash pot 14 against outlet 9. Thus, outlet 9 is closed and gas is unable to flow from the valve chamber 7 into outlet 9. This action blocks the flow of gas in the gas line.

In order to reset the gas safety valve 1 so that the dash pot 14 returns to the open position, once the reason for the drop in downstream pressure has been rectified, an operator simply closes the main valve at the gas source, and presses the button 31 on release valve 30. This allows the gas to be released from the inlet end 3 of the chamber 7 thereby equalizing the pressure in the safety valve 1 and enabling dash pot 14 to be returned to the open position by spring 17. The main valve of the gas source can then be reopened.

If the operator has forgotten to correct the leakage problem, or has not corrected it properly, a very small amount of gas will again escape through the outlet 5, before the dash pot 14 will again move rapidly into the closed position. Thus, with the safety valve 1 in place, at no time can a significant amount of gas pass from the outlet 5 unless the pressure in the gas safety valve 1 is reasonably balanced so that the dash pot 14 remains in the open position.

Disastrous consequences are thus avoided even if the leakage problem has not been corrected and there is an open flame. The preceding process can be conveniently and quickly repeated until the leak has been properly repaired.

Protection is provided in other ways. lfthe leal<age problem has been corrected but the operator inadvertently neglects to turn off the main valve at the source of the pressurized gas, or such valve does not properly close, opening pressure release valve to relieve upstream pressure and return the dash pot 14 to the open position will not succeed.

The dash pot 14 will not return to the open position because the net pressure in the inlet end 3 will be positive and either the dash pot 14 will remain in the. downstream closed position, or the gas will hiss as it escapes the release valve, that is, the operator will detect a leak by means of a continued hissing through bleed passage 29 and release valve 30. As only small amounts of gas will escape through the release valve 30 in such a situation, a potentially hazardous situation is avoided. If the valve at the source has been properly closed, the dash pot 14 will of course move back to the open position when the release valve 30 is opened. When the leak has been properly repaired, the dash pot 14 will remain in the open position and the accepted amount of gas will flow through the gas safety valve 1.

The gas safety valve I also provides protection against drops in pressure on the upstream side of the gas safety valve, or pressure"blow-back"from the downstream end of the gas line. For example, if there is an explosion at the source of gas consumption, a positive pressure from the downstream end will be created which then causes dash pot 14 to move quickly to the upstream closed position against inlet 8 so as to seat O-ring 20a. Thus, any danger of a flame being blown back through the safety valve 1 and into the gas tank is avoided. Many unfortunate accidents and deaths have occurred where the contents of for

example a propane tank have ignited, or a rupture between the tank and the consumption point has occurred, thereby permitting dangerous gas to escape. A particularly hazardous situation involves propane tanks at the rear of a recreation vehicle becoming ruptured due to collision or roll over, or the valve of a propane tank for a gas fired barbecue grill is inadvertently opened by a child.

During manufacture, springs of various tension could be used in otherwise identical safety valves) to act as spring 17. The higher the tension of the spring used, the lower the pressure at the outlet 9 must be for a given pressure at the inlet 8, before the dash pot 14 will move to the closed position. The gas safety valve can also be utilized for liquids, and it is to be understood that"gas", as used in this application, is intended to include a fluid such as a liquid.

As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.