Patent Description:
The present invention is generally directed toward a passive explosion isolation valve that comprises vertically-oriented flaps that are open during normal valve operation permitting communication between the valve inlet and valve outlet, but close automatically in response to an energetic event occurring downstream of the valve. Valves according to the present invention may also be optionally equipped with valve seat cleaning assemblies configured to remove particulate material that has accumulated near the valve seat and that might interfere with complete closure of the flaps in response to the energetic event. In addition, valves according to the present invention are provided with latch assemblies that secure the flaps in the closed position following the energetic event until it is desired to reopen the valve.

Certain kinds of industrial plants employ dust collection systems for removing fine particulate matter from material processing equipment to avoid discharge of the particulate matter into the environment. Such dust collection systems often comprise a baghouse or similar dust collection apparatus in which the particulate matter is collected prior to venting of the air stream into the atmosphere. The particulate matter collected may be highly flammable or even explosive. Isolation devices, in particular isolation valves, are often employed to protect upstream equipment from the disastrous consequences of an explosion within the dust collection apparatus.

Isolation valves can be of the active or passive type. Active isolation valves generally require mechanical actuation in response to a detected hazardous condition, such as a deflagration wave or flame front. Active isolation valves may be of the gate valvetype, such as disclosed in <CIT>, in which shifting of a gate member is effected through actuator apparatus. Another type of active isolation valve is a pinch valve, such as disclosed in <CIT>, in which an inner sleeve is compressed. As with a gate-type isolation valve, closure of the pinch valve sleeve is effected through an actuator device. Active isolation valves, while effective, are generally more complex and require the installation of detection equipment capable of identifying the onset of a hazardous energetic event and triggering the valve-closing actuator, thus resulting in increased capital cost.

Passive isolation valves are generally much less complex and do not rely upon detection devices for their actuation. Rather, passive isolation valves are generally responsive to environmental changes, such as the energetic event itself or changes in pressure or direction of fluid flow. As such, passive isolation valves generally are not actively monitored to ensure their operational readiness, apart from routine inspection and maintenance.

Traditionally, many passive isolation valves have comprised a horizontally-hinged gate element, such as that illustrated in <CIT>, although, such traditional gate elements have more commonly been configured as flat, rather than contoured, members. Nevertheless, being horizontally-hinged has meant that gravitational forces must be considered when designing the gate element as the process stream or any mechanical assisting device must be capable of pivoting the gate element to a valve open position during normal operation of the process equipment, which means that the weight of the gate element that will naturally tend to bias the gate element to the closed position must be overcome. As the valve diameter increases, the size of the gate element required also increases, which adds weight to the gate element. To conserve weight, the gate element may be constructed from thinner material. Additionally, a larger gate element results in a greater path of travel that for the gate element when shifting between the valve open and valve closed positions leading to longer closure times in response to an energetic event.

Hinged gate elements have also been known to suffer from valve "chattering," which is the occasional slamming of the gate element against the valve seat and/or stop members due to normal fluctuations in flow of the process stream through the valve. If the gate element is constructed of too thin of material, this chatter can lead to deformation of the gate element and failure of the gate element to properly block communication between the valve inlet and valve outlet when the valve has shifted to a closed position in response to a downstream energetic event. Thus, upstream process equipment may not be effectively isolated from the effects of the energetic event.

In dust collection systems, accumulation of particulate matter near the valve can adversely impact the valve's effectiveness in preventing propagation of an energetic event by interfering with full closure of the valve's gate element. The '<NUM> patent discloses one solution to this problem. However, the described solution is specific to the particular valve shown having a horizontally-hinged gate element.

<CIT> describes a back pressure flap valve arrangement. The arrangement comprises a housing having an inlet opening and an outlet opening adapted for connection of the housing to a ducting, and at least one side wall extending along a flow direction through the housing from the inlet opening to the outlet opening. A flap is pivotably hinged about a shaft thereby being movable between an open position and a closed position, said shaft extending transverse the flow direction. At least one locking device is fixedly mounted to the side wall and comprises a locking pin and a stopping member. The locking pin is movable between a retracted position and a locking position, and being biased towards said locking position. The stopping member is movable from a stop position in which the stopping member is adapted to hold the locking pin in its retracted position, to a release position by the flap acting on the stopping member in case of a back pressure. Thereby the locking pin is allowed to move into the locking position in which the locking pin maintains the flap in the closed position.

The present invention seeks to overcome one or more of the shortcomings noted above with prior art passive isolation valves. According to one embodiment of the present invention the problems associated with valves comprising a horizontally-hinged gate element are addressed by dividing the valve closure into two independent and smaller masses. In addition, the smaller gate elements may be vertically-hinged to lessen or remove the impact of gravitational forces acting thereon. According to one particular embodiment there is provided a passive isolation valve comprising a valve body, a gate assembly secured to the valve body that comprises a pair of vertically-hinged gate members, and one or more latch assemblies. The valve body comprises a valve inlet, a valve outlet, and a valve passage through the valve body that interconnects the inlet and outlet. The gate members are shiftable, in response to an energetic event downstream of the valve outlet, between a valve open position, in which the valve inlet is in communication with the valve outlet, and a valve closed position, in which the gate members block communication between the valve inlet and the valve outlet. The gate assembly further comprises at least one biasing mechanism configured to bias the gate members toward the valve open position. The one or more latch assemblies are configured to be deployed in response to shifting of the gate members to the valve closed position and to hold the gate members in the valve closed position.

According to another embodiment of the present invention the problem of accumulation of particulate material that affects valve closure is addressed by providing a novel valve seat cleaning assembly. In particular, there is provided a passive isolation valve comprising a valve body, a gate assembly secured to the valve body comprising one or more hinged gate members, a valve seat, and a valve seat cleaning assembly configured to remove accumulated particulate matter from the vicinity of the valve seat. The valve body comprises a valve inlet, a valve outlet, and a passage through the valve body interconnecting the valve inlet and the valve outlet. The one or more hinged gate members are shiftable, in response to an energetic event downstream of the valve outlet, between a valve open position, in which the valve inlet is in communication with the valve outlet, and a valve closed position, in which the one or more gate members block communication between the valve inlet and the valve outlet. The one or more gate members contact against the valve seat when in the valve closed position. The valve seat cleaning assembly is configured to remove accumulated particulate matter from the vicinity of the valve seat that might interfere with seating of the one or more gate members against the valve seat during shifting of the one or more gate members between the valve open and the valve closed positions. The valve seat cleaning assembly comprises a gas-directing channel and a gas-dispersing guide that faces the gas-directing channel. The gas-dispersing guide comprises a plurality of ports that are in communication with the gas-directing channel and configured to disperse a gas flowing through the gas-directing channel into the passage in the vicinity of the valve seat.

According to yet another embodiment of the present invention there is provided a passive isolation valve comprising a valve body, a gate assembly secured to the valve body comprising one or more hinged gate members, and at least one latch assembly for the one or more gate members. The valve body comprises a valve inlet, a valve outlet, and a passage through the valve body interconnecting the valve inlet and the valve outlet. The gate members are shiftable, in response to an energetic event downstream of the valve outlet, between a valve open position, in which the valve inlet is in communication with the valve outlet, and a valve closed position, in which the one or more gate members block communication between the valve inlet and the valve outlet. The at least one latch assembly is configured to be deployed in response to shifting of the gate members to the valve closed position and to hold the gate members in the valve closed position. The at least one latch assembly comprises a trigger configured to be contacted by the one or more gate members during shifting of the one or more gate members between the valve open and valve closed positions, a securing element configured to restrict movement of the one or more gate members from the valve closed position, and a shiftable body that is configured, upon activation of the trigger, to move the securing element into engagement with the one or more gate members.

While the drawings do not necessarily provide exact dimensions or tolerances for the illustrated components or structures, the drawings are to scale with respect to the relationships between the components of the structures illustrated in the drawings.

The following description is intended to illustrate a preferred embodiment of the present invention and should not be viewed as limiting upon the scope of the invention as defined by the appended claims. It will be recognized that not all structures or features described herein are critical to practicing the concepts of the present invention and that the invention can be practiced in alternate ways without departing from the scope thereof.

Turning to <FIG>, a passive isolation valve <NUM> is illustrated. The valve <NUM> comprises a valve body <NUM> coupled to an inlet duct <NUM> and an outlet duct <NUM>. Each of ducts <NUM> and <NUM> comprises a flange <NUM> that is configured to be secured to respective body inlet flange <NUM> and body outlet flange <NUM>, such as with bolts <NUM>. As used herein, the terms "inlet" and "outlet" generally refer to the upstream and downstream sides, respectively, of valve <NUM> during normal operation thereof in the valve open configuration when installed within process equipment. Thus, the inlet of valve <NUM> receives the process flow during valve-open operation, which, upon passage through the valve, exits via the outlet of the valve.

Valve body <NUM> is generally of cylindrical configuration and may be configured with a window <NUM> that during operation of the valve is covered by a shield <NUM>. Shield <NUM> is secured to valve body by a closure mechanism <NUM>. Window <NUM> permits inspection of the interior of valve body <NUM> without having to decouple the valve body from ducts <NUM> and <NUM>.

<FIG> provides an expanded assembly view of the various components of valve <NUM>. Valve body <NUM> generally comprises a valve inlet <NUM> and a valve outlet <NUM> and a passage <NUM> through the valve body that interconnects inlet <NUM> and outlet <NUM>. Valve <NUM> also comprises a gate assembly <NUM> that comprises at least one, and preferably two, hinged gate members <NUM>, <NUM>. As explained in greater detail below, gate members <NUM>, <NUM> are shiftable, in response to an energetic event downstream of the valve outlet, between a valve open position, in which the valve inlet <NUM> is in communication with the valve outlet <NUM>, and a valve closed position, in which the gate members <NUM>, <NUM> block communication between the valve inlet <NUM> and the valve outlet <NUM>.

According to the claimed invention, the valve <NUM> comprises one or more latch assemblies <NUM> that are configured to be deployed in response to shifting of the gate members <NUM>, <NUM> to the valve closed position and to hold the gate members <NUM>, <NUM> in the valve closed position until it is desired to reopen the valve. A preferred embodiment of latch assembly <NUM> is described in further detail below.

In certain embodiments, the valve <NUM> may further comprise a valve seat cleaning assembly <NUM> that is configured to remove accumulated particulate matter from the vicinity of a seat <NUM> (see, <FIG>) for the gate members <NUM>, <NUM> when the gate members shift from the valve open to the valve closed position. In particular embodiments, the valve seat cleaning assembly <NUM> utilizes a pressurized gas to cause particulate matter that has settled in the immediate area of the valve seat <NUM> to become resuspended in a stream of process gas flowing through the valve passage <NUM>. A preferred embodiment of the valve seat cleaning assembly is described in further detail below.

Referring to <FIG>, a preferred embodiment of the gate assembly <NUM> is depicted. As previously described, gate assembly <NUM> comprises a pair of gate members <NUM>, <NUM>. Gate members <NUM>, <NUM> are shown as being independently hinged, which permits the gate members <NUM>, <NUM> to pivot independently of each other, especially between the valve open and valve closed positions, although this need not always be the case, nor does it mean that the action of each gate member needs to be entirely independent from the other.

It can be desirable to provide a biasing mechanism <NUM>, which may be in the form of a coil spring, that interconnects the gate members <NUM>, <NUM> and operates to bias the gate members toward the valve open position. Thus, biasing mechanism <NUM> helps to maintain valve <NUM> in a maximum state of openness even if the intensity of the flow of the process stream through valve <NUM> temporarily subsides or is halted completely. When biasing mechanism <NUM> comprises a coil spring as depicted, each end of the spring may be secured to a post or bolt <NUM> installed in gate members <NUM>, <NUM> and affixed to a downstream face <NUM>, <NUM> of each gate member. In certain embodiments, gate assembly <NUM> may also include one or more stops <NUM> that restricts movement of gate members <NUM>, <NUM> in the valve open position and sets a maximum path of travel for the gate members when the process stream is flowing through valve <NUM>. Stop <NUM> may be affixed to the valve body <NUM> or any part thereof, such as mounting ring <NUM>, by fasteners <NUM>. In certain embodiments, stops <NUM> are configured to permit a maximum path of travel for gate members <NUM>, <NUM> of approximately <NUM>°, approximately <NUM>°, or approximately <NUM>° relative to the valve closed position. In particular embodiments, valve design is configurable to permit the end user to set the maximum degree of openness for gate members <NUM>, <NUM> during normal operation of valve <NUM>. This can be accomplished by providing specific mounting positions for the stops <NUM> or by providing alternate stop geometries that the end user can install. The configuration may take into account the hazard that is likely to be encountered within the process equipment and how quickly the valve <NUM> needs to be closed to protect upstream equipment.

As illustrated, the inboard segments <NUM>, <NUM> of each of gate members <NUM>, <NUM> has been rolled to form an elongate bore <NUM> into which a hinge pin <NUM> may be inserted. Thus, in the illustrated embodiment, each gate member <NUM>, <NUM> pivots about a different axis, although it is preferred for the two pivot axes to be substantially parallel. It will be appreciated that other hinge structures may be employed to mount gate members <NUM>, <NUM> besides that illustrated in the drawings. For example, the rolled sections <NUM>, <NUM> of each gate member may be cut away in alternating fashion so that the rolled sections can be fitted together and a single hinge pin <NUM> used to mount the gate members around a common pivot axis. Still alternatively, the hinge pins may be welded to the gate members so that formation of bore <NUM> is avoided. Further yet, bore <NUM> may be formed from a round tube that has been welded onto each gate member <NUM>, <NUM>. Still further yet, round bars may be welded to the gate members, with the ends of the respective round bars being drilled or tapped so that bolts could be inserted in place of hinge pins <NUM>.

It is preferred, although not essential in every embodiment according to the present invention, for gate assembly <NUM> to be configured such that when valve <NUM> is installed within particular process equipment, the gate members <NUM>, <NUM> pivot about a vertically oriented axis or axes. Thus, in these embodiments, the gate members <NUM>, <NUM> would pivot without regard to the effect of gravity on the pivoting action. Although, it is within the scope of the present invention for gate members <NUM>, <NUM> to be obliquely oriented with respect to valve body <NUM> and passage <NUM> therethrough. It is preferred, however, to avoid configuring gate assembly <NUM> so that gate members <NUM>, <NUM> pivot about a horizontal or substantially horizontal axis or axes when valve <NUM> is installed within process equipment as the force of gravity acting upon members <NUM>, <NUM> when in the valve open configuration would have to be considered when providing structure to bias the members open or closed as necessary. In particular embodiments, verticality of the pivot axis or axes is provided to an accuracy of ±<NUM>°, ±<NUM>°, or ±<NUM>°.

In certain embodiments, it is possible to mount valve <NUM> such that the process flow is travelling vertically therethrough. For example, valve <NUM> may be mounted downstream of a <NUM>° elbow in the process conduit. In such embodiments, the axis or axes about which gate members <NUM>, <NUM> pivot would no longer be substantially vertically oriented. Rather, the axis or axes about which members <NUM>, <NUM> pivot would be substantially horizontally oriented. Thus, gravitational effects acting upon gate members <NUM>, <NUM> would need to be taken into account in designing valve <NUM> and/or other parts of the system in which the valve is installed. For example, if the process flow is travelling vertically upward through the valve <NUM> (i.e., against gravity), the effects of gravitational forces acting upon gate members <NUM>, <NUM> to shift the gate members to the valve closed position would need to be countered. Such forces could be counterbalanced through use of a stronger biasing mechanism <NUM> to maintain the gate members <NUM>, <NUM> in the valve open position. If the process flow is travelling vertically downward through the valve (i.e., with gravity), the gravitational forces will tend to assist in maintaining the gate members <NUM>, <NUM> in the valve open position thereby reducing or eliminating the need for biasing mechanism <NUM>. Alternatively, biasing mechanism <NUM> could be reconfigured and/or repurposed to provide a valve-closed biasing force so that upon experiencing upstream propagation of an energetic event, biasing mechanism <NUM> could assist with overcoming gravitational forces encountered during shifting of gate members to the valve closed position. Therefore, instead of being under tension as in the embodiments illustrated in the Figures, biasing mechanism <NUM> could be provided under compression in this particular embodiment, if necessary.

As illustrated, a mounting ring <NUM> may be provided to which gate members <NUM>, <NUM> are directly attached. Mounting ring <NUM> may then in turn be fastened to the main valve body <NUM>. However, it is within the scope of the present invention for mounting ring <NUM>, or similar structure, to be unitarily formed with valve body <NUM> rather than provided as a separate part. Mounting ring <NUM> comprises a central opening <NUM> configured to align and/or be coaxial with the longitudinal axis of the valve passage <NUM>. In certain embodiments, mounting ring <NUM> presents substantially the same inner diameter as the main valve body <NUM>, but this need not always be the case. Mounting ring <NUM> also comprises at least one opening that is generally perpendicular to the central opening <NUM> through which hinge pin(s) <NUM> may be received. At least one other opening <NUM> may be formed in mounting ring <NUM> opposite from opening(s) <NUM> in which the distal end of pin(s) <NUM> may be anchored. Generally, opening <NUM> need not be a through bore interconnecting the interior and exterior of ring <NUM> as with opening <NUM>. In addition, one or more bushings <NUM> may be received within openings <NUM>, <NUM> and through which pin(s) <NUM> may be inserted to provide for smoother rotation of gate members <NUM>, <NUM> and to prevent frictional wear of ring <NUM> and pin(s) <NUM>.

As noted above, and as illustrated in <FIG>, valve <NUM> comprises valve seat <NUM> which gate members <NUM>, <NUM> contact when in the valve closed position. Since the valve seat <NUM> faces a downstream direction relative to normal passage of the process stream through valve <NUM>, a small dead space of limited gas circulation can be created in the immediate vicinity of the seat. Particulate matter suspended within the process stream can settle within this dead space and accumulate. This is problematic as any accumulated particulate material can interfere with full closure of gate members <NUM>, <NUM> in response to a downstream energetic event. Therefore, certain embodiments of the present invention comprise a valve seat cleaning assembly <NUM> that functions to remove such accumulated material from the vicinity of valve seat <NUM> that would interfere with seating of gate members <NUM>, <NUM> against the valve seat potentially permitting the energetic event to propagate upstream of valve <NUM> and damage upstream process equipment.

A preferred valve seat cleaning assembly <NUM> is illustrated in <FIG> and comprises an inlet ring <NUM> that can be fastened to mounting ring <NUM>, or directly to valve body <NUM>, as the case may be. In certain embodiments, inlet ring <NUM> comprises the valve seat <NUM>; however, it is within the scope of the present invention for the valve seat <NUM> to be formed within another portion of the valve structure if desired. Inlet ring <NUM> comprises a gas-directing channel <NUM>, representing a recessed portion of the inlet ring, that is fluidly connected to a gas inlet <NUM> that is configured to be connected to a source of pressurized gas (not shown). As illustrated, channel <NUM> essentially forms a complete circle about inlet ring <NUM> so as to provide cleaning through essentially all <NUM>° of the valve seat; however, this need not always be the case. Gas inlet <NUM> may be positioned on inlet ring <NUM> so that gas-directing channel <NUM> only partially circumscribes ring <NUM>, particularly in and around the bottom region of valve seat <NUM> where it most likely for particulate materials to accumulate under the force of gravity.

Valve seat cleaning assembly <NUM> further comprises a gas-dispersing guide <NUM>, which is preferably in the form of a ring-shaped member that encircles the valve inlet <NUM>, although this need not always be the case as noted above. Gas-dispersing guide <NUM> is installed within a recess <NUM> formed in mounting ring <NUM>, faces gas-directing channel, <NUM> and comprises a plurality of ports <NUM> that are in communication with channel <NUM> and configured to disperse a gas flowing through the gas-directing channel into the valve passage <NUM> in the vicinity of the valve seat <NUM>. As used herein, the expression "in the vicinity of the valve seat" refers primarily to that portion of the valve passage <NUM> that encompasses any dead space in which the velocity of gas circulating there within is insufficient to maintain particulate matter suspended within the gas stream flowing through valve <NUM>, such that the particulate matter may accumulate within the passage. In particular, this expression may also encompass at least a portion of or all the pathway that gate members <NUM>, <NUM> must travel when transitioning from the valve open to valve closed position, especially the last <NUM>°, the last <NUM>°, or the last <NUM>° of the path of travel of the gate members.

In certain embodiments, ports <NUM> are distributed substantially uniformly about the gas-dispersing guide <NUM> so that the gas that is dispersed from the valve seat cleaning assembly <NUM> is evenly distributed in the specific region of the valve to be treated. In preferred embodiments, ports <NUM> include respective nozzle <NUM> and throat sections <NUM>, which act to throttle the flow of gas through the ports to create a jet-like action. The operation of valve seat cleaning assembly <NUM> is explained in further detail below.

Inlet ring <NUM> may also be configured with a hinge cover <NUM> that protects the gate assembly hinge structure. A gasket <NUM> may be provided and placed between inlet ring <NUM> and mounting ring <NUM> to provide a seal to prevent escape of the process stream therebetween. In particular, gasket <NUM> is received within a recess <NUM> formed in inlet ring <NUM>. In addition, a pair of D-shaped gaskets <NUM> are also provided and received within recess <NUM> formed in inlet ring <NUM>. Recess <NUM> is located inboard of recess <NUM> on the inlet ring <NUM>. Hinge cover <NUM> also comprises recesses <NUM> and <NUM> that are also configured to receive respective portions of gaskets <NUM>. D-shaped gaskets <NUM> are configured to form a part of valve seat <NUM> and against which gate members <NUM>, <NUM> contact when in the closed position. Gasket <NUM> can be made of a material that meets the performance needs of a particular application. Exemplary materials include ethylene propylene diene terpolymer (EPDM), silicon, and nitrile rubber. As mentioned previously, the dead space behind valve seat <NUM> presents an area in which particulate matter may accumulate and this can negatively affect the ability of the valve to close properly. However, one unexpected benefit of this dead space, though, is that the gaskets <NUM> remain very well protected from high velocity process media abrasion effects. Thus, the selection of an appropriate gasket material does not have to place as much emphasis on abrasion resistance as other characteristics for the gasket material, which can be an advantage.

<FIG> illustrate more closely an embodiment of a latch assembly <NUM> according to the present invention. It is noted that the illustrated embodiment represents a preferred type of latch assembly that may be used with the valve <NUM>, and that other latching mechanisms that provide a similar functionality may also be used without departing from the scope of the present invention as defined by the appended claims. In addition, it is not within the scope of the present invention for valve <NUM> to utilize no latching mechanism at all. The number and positioning of latch assemblies <NUM> within valve <NUM> are generally dependent upon the valve diameter and gate member size. The large the valve diameter and gate member size, generally the more latch assemblies that will be used to secure the gate members upon valve closure. If only one latch assembly <NUM> is required per gate member for a particular application, generally the latch assembly <NUM> would be positioned at the three-o'clock or the nine-o'clock position (i.e., about <NUM>° from either top or bottom dead center of the valve passage <NUM>) about the mounting ring <NUM>. If more than one latch assembly <NUM> is required per gate member to ensure sufficient securement of the gate members in the valve closed position, the latch assemblies are preferably uniformly spaced about mounting ring <NUM>. As illustrated in the Figures, two latch assemblies <NUM> are provided for each of gate members <NUM>, <NUM>. Latch assemblies <NUM> are spaced about <NUM>° apart from each other, and about <NUM>° from the pivot point for each respective gate member.

According to the claimed invention, latch assembly <NUM> is configured to be deployed in response to shifting of the gate members <NUM>, <NUM> to the valve closed position and to hold the gate members in the valve closed position. Latch assembly <NUM> comprises a latch base member <NUM> to which the various components making up the latch assembly <NUM> may be secured. Base member <NUM> may be configured for installation within the valve body <NUM>, or, as illustrated in the figures, within mounting ring <NUM> through orifices <NUM> and notches <NUM>.

Latch assembly <NUM> comprises a trigger <NUM> that is configured to be contacted by one of gate members <NUM>, <NUM> during shifting of the gate member between the valve open and valve closed positions. In the illustrated embodiment, trigger <NUM> is biased toward an undeployed position by a small coil spring <NUM> and secured thereto by a retaining pin <NUM>. Trigger <NUM> is configured so that contact with one of gate members <NUM>, <NUM> causes a securing element <NUM> to deploy. Securing element <NUM> is configured to restrict movement of the gate members <NUM>, <NUM> from the valve closed position until the hazard condition downstream of valve <NUM> that caused valve <NUM> to close has subsided and it has been deemed safe to reopen the valve. Securing element <NUM> restricts movement of the gate members <NUM>, <NUM> by physically engaging the downstream faces <NUM>, <NUM> of the gate members to prevent rotational movement about hinge pins <NUM>. Securing element <NUM> is fastened to base member <NUM> by a hinge pin <NUM> and biased toward a retracted or undeployed position by a spring <NUM>.

Latch assembly <NUM> comprises a shiftable body <NUM> that is received within a bore <NUM> formed in a body housing <NUM> that is threadably received within an orifice <NUM> formed in base member <NUM>. A spring <NUM> is positioned within bore <NUM> and about body <NUM>. Spring <NUM> is configured to engage a flange <NUM> extending from body <NUM> and a shoulder <NUM> within bore <NUM>. Shifting of body <NUM> into a retracted position, as illustrated in <FIG>, compresses spring <NUM> in between flange <NUM> and shoulder <NUM>. Body <NUM>, when retracted and valve <NUM> is in the valve open position, is held in place by a retaining member <NUM> that is configured to mate with a groove <NUM> formed in body <NUM>. Retaining member <NUM> is connected to an L-shaped flat spring <NUM> that is secured to base member <NUM> by a fastener <NUM>. Flat spring <NUM> is configured to reside generally within a recessed portion <NUM> of base member <NUM>. A bushing <NUM> is also provided within bore <NUM> into which body <NUM> may be received. Bushing <NUM> may also include an orifice <NUM> into which retaining member may be inserted to hold body <NUM> in the retracted position. A cover <NUM> may be provided for attachment to base member <NUM> and to cover mounting ring notch <NUM> when latching assembly <NUM> is installed within mounting ring <NUM>. A threaded nut <NUM> is provided around body housing <NUM> and is operable to assist with securing latch assembly <NUM> to mounting ring <NUM> once installed within notch <NUM>.

It is noted that latch assembly <NUM> may have applications beyond those described herein and apart from isolation valve <NUM>. Therefore, latch assembly <NUM> should be viewed as a standalone device with utility that is independent from isolation valve <NUM>, as well as a device that can be used in conjunction with isolation valve <NUM>.

The operation of valve <NUM> will now be described in greater detail. Valve <NUM> is configured to be installed within process equipment, and particularly intermediate inlet duct <NUM> and outlet duct <NUM> in applications to protect upstream process equipment (not shown) from damage due to energetic events occurring downstream of valve <NUM>. Such energetic events include, but are not limited to, explosions associated with detonation of carbon-containing fine particulate materials. Preferably, valve <NUM> is installed so that gate members <NUM>, <NUM> are oriented vertically within valve passage <NUM> and at the inlet or upstream end of the valve. Although, as noted previously, modifications to this configuration are contemplate herein without departing from the scope of the present invention.

A process stream may then be flowed through valve <NUM>. In certain embodiments, the process stream comprises particulate matter suspended in a pneumatic stream. The process stream enters valve <NUM> and impinges upon gate members <NUM>, <NUM>. If the velocity of the process stream is sufficient, gate members <NUM>, <NUM> may be shifted to open the valve <NUM> even more than what is provided by spring <NUM>, and possibly contacting stops <NUM>.

As noted previously, some portion of the process stream may enter the dead space near valve seat <NUM> where the velocity of the process gas will be insufficient to keep the particulate material carried thereby suspended. The particulate material may then drop out and accumulate adjacent to the valve seat <NUM>. Preferably, and as illustrated in the Figures, valve <NUM> is equipped with a valve seat cleaning assembly <NUM>. Gas inlet <NUM> is coupled to a source of pressurized gas, such as compressed air, which is then conducted through inlet <NUM> and into gas-directing channel <NUM>. The pressurized gas is delivered into ports <NUM>, and directed through throat sections <NUM> and nozzle sections <NUM> and into valve passage <NUM> in the vicinity of valve seat <NUM> to remove accumulated particulate material that might prevent seating of gate members <NUM>, <NUM> during shifting of the gate members to the closed position as depicted in <FIG>. The pressurized gas supplied to and discharged from valve seat cleaning assembly <NUM> may be a continuous flow or it can be pulsed with high-intensity bursts occurring at random or regular intervals.

Should an energetic event, such as a detonation, occur downstream of valve <NUM>, valve <NUM> is configured to respond passively to isolate equipment located upstream of the valve by closing. Valve <NUM> accomplishes this by harnessing the forces generated by the detonation, such as percussive forces traveling upstream through the process equipment, to shift gate members <NUM>, <NUM> from a valve open position in which the valve inlet <NUM> communicates with the valve outlet <NUM> to a valve closed position in which the gate members block communication between the inlet and outlet. According to the claimed invention, and as illustrated in the Figures, valve <NUM> is equipped with one or more latch assemblies <NUM> that are configured to secure the gate members <NUM>, <NUM> in the valve closed position once this shifting has occurred.

Turning now to <FIG>, operation of the latch assemblies is described. <FIG> is a close-up view of a latch assembly <NUM> in its undeployed state, such as when the valve would be normally operating in the valve open position. As gate member <NUM> pivots about its respective hinge pin <NUM> in response to the downstream energetic event, the outboard edge of the gate member will contact the tip <NUM> of trigger <NUM> thereby causing trigger <NUM> to rotate about the shaft <NUM> of retaining pin <NUM> against the bias of spring <NUM>. This rotation creates a cam-like action in that end <NUM> of trigger <NUM> engages end segment <NUM> of flat spring <NUM> thereby elevating end segment <NUM> away from recessed portion <NUM>. This in turn also causes retaining member <NUM>, which passes through slot <NUM> of flat spring <NUM> to be displaced laterally and disengage groove <NUM> of body <NUM>. Once retaining member <NUM> disengages groove <NUM>, body <NUM> is released and free to slide within bore <NUM> under the force of spring <NUM>.

As illustrated in <FIG>, as body <NUM> slides under the force of spring <NUM>, the end <NUM> of the body contacts a groove <NUM> formed in securing element <NUM>. As body <NUM> continues to contact securing element <NUM> and slide through groove <NUM>, securing element shifts against the bias of spring <NUM> to a deployed position as depicted in <FIG>. Further, as can be seen in <FIG>, securing element now directly engages downstream face <NUM> of gate member <NUM> thereby holding gate member <NUM> against valve seat <NUM> preventing it from shifting from the valve closed position.

When desired to place valve <NUM> back into service following the energetic event, the latch assemblies <NUM> can be reset to an undeployed position so that gate members <NUM>, <NUM> can be released and be free to pivot to the valve open position once again. To reset latch assembly <NUM>, body <NUM> is shifted within bore <NUM> in a direction away from securing element <NUM> that causes spring <NUM> to be compressed. Retraction of body <NUM> can be accomplished by various means. In one embodiment, a tool (not shown) may be attached to distal end <NUM> of body <NUM>, and in particular by insertion into opening <NUM>, which may be threaded. The operator can the manually shift body <NUM> against the bias of spring <NUM> until retaining member <NUM> becomes locked into groove <NUM> thereby holding body <NUM> in the retracted position.

While body <NUM> is being retracted, it comes out of engagement with securing element <NUM>, which causes spring <NUM> to shift securing element <NUM> to the retracted position as illustrated in <FIG> and out of contact with gate member <NUM>. Gate member <NUM>, under the biasing influence of spring <NUM>, shifts toward the open position and rotates trigger <NUM> to a neutral position before trigger <NUM> can return to the undeployed position resulting from the engagement of holding body <NUM> and groove <NUM>.

Although not illustrated, it is within the scope of the present invention for valve <NUM> to be equipped with sensors that provide an operator with operational status information about valve <NUM>. For example, sensors may be placed on gate members <NUM>, <NUM> to provide real time information regarding the state of openness thereof. Sensors may also be placed in association with latch assemblies <NUM> to indicate whether a latch assembly has been activated. For example, if one latch assembly has been activated, but not all, such could signal a malfunction of the latch assembly and a need for servicing.

Claim 1:
A passive isolation valve (<NUM>) comprising:
a valve body (<NUM>) comprising a valve inlet (<NUM>), a valve outlet (<NUM>), and a passage (<NUM>) through the valve body (<NUM>) interconnecting the valve inlet (<NUM>) and the valve outlet (<NUM>);
a gate assembly (<NUM>) secured to the valve body (<NUM>), the gate assembly (<NUM>) comprising one or more hinged gate members (<NUM>, <NUM>) that are shiftable, in response to an energetic event downstream of the valve outlet (<NUM>), between a valve open position, in which the valve inlet (<NUM>) is in communication with the valve outlet (<NUM>), and a valve closed position, in which the one or more gate members (<NUM>, <NUM>) block communication between the valve inlet (<NUM>) and the valve outlet (<NUM>); and
at least one latch assembly (<NUM>) configured to be deployed in response to shifting of the one or more gate members (<NUM>, <NUM>) to the valve closed position and to hold the one or more gate members (<NUM>, <NUM>) in the valve closed position.
the at least one latch assembly (<NUM>) comprising a trigger (<NUM>) configured to be contacted by the one or more gate members (<NUM>, <NUM>) during shifting of the one or more gate members (<NUM>, <NUM>) between the valve open and valve closed positions,
characterized in that
the at least one latch assembly (<NUM>) further comprises a securing element (<NUM>) fastened to a base member (<NUM>) of the latch assembly (<NUM>) by a hinge pin (<NUM>), biased toward a retracted or undeployed position by a spring (<NUM>) and configured to restrict movement of the one or more gate members (<NUM>, <NUM>) from the valve closed position, and a shiftable body (<NUM>) that is configured, upon activation of the trigger (<NUM>), to move the securing element (<NUM>) into engagement with the one or more gate members (<NUM>, <NUM>).