Backflow prevention valve

Abstract

The backflow prevention valve comprises various embodiments for installation in a liquid conduit for the prevention of reverse flow therethrough. The valve is particularly well suited for installation in a fire hydrant, where it prevents the illicit backflushing of the water system with contaminants. The valve may be constructed for use with either dry barrel hydrants, i.e., where the water is drained from the hydrant when the water is shut off, or wet barrel hydrants, where water remains in the hydrant body at all times. The valve may be constructed with a cylindrical body or with a thinner ring for the body, depending upon the installation desired. Each embodiment includes a series of generally triangular leaves hinged about the inner circumference of the valve body, which close against the central control rod or against one another at their apices when water is not flowing therethrough.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to fluid control valves, and more particularly to a valve that is particularly well configured to prevent fluid backflow in systems configured for relatively high flow rates and pressures. The present valve may be readily adapted for use in both wet and dry barrel fire hydrants to prevent contamination of the water supply therethrough, or may be adapted to other relatively high pressure and high flow fluid systems requiring one-directional flow and backflow prevention.

2. Description of the Related Art

Fire hydrant systems are generally connected to a central municipal high pressure water supply source. The hydrants themselves are configured to provide relatively large fluid flows, as necessary to quench a large fire. Hydrants are nearly universally readily accessible, in order to provide for rapid connection of hoses and opening of the hydrant valve since time is critical in fighting fires. Hydrants are generally not equipped with backflow prevention valves for the main water flow, as in the past there has been no apparent reason that such valves would be needed in hydrant installations.

The ready accessibility to the water supply by means of fire hydrants has resulted in various users tapping into the water supply for various reasons. In many cities, street sweepers and construction water tank trucks will have their water tanks refilled by means of readily available municipal hydrants. This is generally not of great concern, as it does not affect the water supply to any significant degree.

However, the access to fire hydrant water supplies by non-firefighting personnel leaves the door open for potentially tragic misuse of such a system. It has occurred to the present inventor that one or more terrorists could easily contaminate a municipal water supply, merely by pumping contaminated water or other liquid back into the water supply through an easily accessible hydrant. A terrorist would need nothing more than a relatively small tanker truck or water tank on a trailer, and a pump providing higher pressure than the municipal water supply in the hydrant system. Contaminated water or other liquid could be pumped back into the municipal water supply, thereby contaminating the entire municipal water supply, or at least a good portion of it, depending upon the contaminant and its spread or proliferation in the water supply.

Accordingly, the present inventor has developed a solution to this potential problem by means of a backflow prevention valve which is readily adaptable for installation in existing fire hydrants of various types, and which may be adapted to other fluid flow systems as well. The present valve essentially comprises a series of generally triangular vanes which are pivotally attached at their bases to the inside of a cylindrical insert which is installed between the base of the hydrant and the underlying standpipe or shoe. Various embodiments of the present backflow prevention valve provide for installation within both dry barrel and wet barrel type hydrants, with the cylindrical insert having a flanged fitting(s) for bolting between the hydrant components, or other conventional attachment as required. The present valve is completely automatic in its operation, opening as water flow through the hydrant and out the hydrant outlet(s) pushes it open, and automatically closing when the flow is shut off. Any frangible, breakaway couplings or components used with the original hydrant are retained when the present backflow prevention valve is installed. The present valve is not accessible without removing the hydrant from its base, thereby precluding tampering by unauthorized persons.

A discussion of the related art of which the present inventor is aware, and its differences and distinctions from the present invention, is provided below.

U.S. Pat. No. 3,185,171 issued on May 25, 1965 to Frank H. Mueller et al., titled “Valving Structure For Fire Hydrant,” describes a hydrant configuration having an easily replaceable seat assembly for the control valve in the base thereof. The Mueller et al. U.S. patent also discloses a frangible, breakaway control valve rod coupling and flanged hydrant attachment to provide for ease of replacement of the hydrant in the event that it is struck from its base (e.g., automobile collision, etc.). However, no backflow prevention valve, automated or otherwise, is disclosed by Mueller et al. in their patent.

U.S. Pat. No. 3,506,027 issued on Apr. 14, 1970 to John T. Dunton, titled “Fire Hydrant,” describes a “dry barrel” type hydrant having relatively small one way valves installed in the drain ports thereof. Dry barrel hydrants conventionally automatically drain the water from the barrel after use, to prevent freezing of any remaining water in the barrel and resultant damage to the hydrant barrel. The Dunton device comprises rubber flapper valves which are pushed closed due to water pressure in the upper portion of the hydrant, and which open when the water is shut off to allow water to drain from the upper barrel of the hydrant. No large capacity backflow prevention valve for flow from the hydrant supply and through the barrel is disclosed by Dunton.

U.S. Pat. No. 3,850,190 issued on Nov. 26, 1974 to Donald K. Carlson, titled “Backflow Preventer,” describes a flexible toroidal seal, the inner lip of which seals against a hemispherical shell in the center of the assembly. Fluid may flow in one direction through a series of peripheral ports around the central shell. The device is not adaptable for use in preventing backflow through the central barrel of a fire hydrant, as the flexible seal would not hold against significant backflow pressure in such a relatively large diameter installation. Moreover, the Carlson valve could not be installed in a fire hydrant to prevent backflow, as the central shell would preclude passage of the control valve stem therethrough in a wet barrel type hydrant. The Carlson valve also has outlets to release any backflowing fluid to the exterior of the valve, which would be unacceptable where a contaminated fluid of some sort is being introduced into the system.

U.S. Pat. No. 3,980,096 issued on Sep. 14, 1976 to Daniel A. Ellis et al., titled “Fire Hydrant,” describes a hydrant control valve configuration which allows the valve to remain with the hydrant shoe when the barrel is removed therefrom. No backflow prevention valve of any type is disclosed.

U.S. Pat. No. 3,980,097 issued on Sep. 14, 1976 to Daniel A. Ellis, titled “Fire Hydrant With Drain Valve And Backflow Preventer Mechanism,” describes the installation of small backflow prevention valves in the drain ports of a dry barrel type hydrant. These valves are much too small to serve as a backflow prevention valve for the main flow through the hydrant barrel, as provided by the present invention. In any event, the Ellis valves have no central clearance for a valve control shaft in a dry barrel type hydrant, as provided by at least one embodiment of the present invention.

U.S. Pat. No. 4,073,307 issued on Feb. 14, 1978 to John H. Royce, titled “Valve For Fire Hydrants,” describes a generally conventional control valve in which the resilient valve facing material includes a circumferential lip extension. Royce states that this provides a better seal when the valve is closed. However, no form of backflow prevention valve is disclosed by Royce.

U.S. Pat. No. 4,117,856 issued on Oct. 3, 1978 to Donald E. Carlson, titled “Frostproof Backflow Preventer,” describes a one way valve closely resembling the valve of the '190 U.S. patent to the same inventor, discussed further above. The same differences noted between that device and the present invention are seen to apply here as well.

U.S. Pat. No. 4,139,931 issued on Feb. 20, 1979 to John H. Royce, titled “Assembly Method For Fire Hydrants,” is a division of the parent application upon which the issued '307 U.S. patent (discussed further above) is based. The same differences noted above between the device of the '307 U.S. patent and the present invention are seen to apply here as well.

U.S. Pat. No. 4,483,361 issued on Nov. 20, 1984 to Edward J. Jungbert, Sr., titled “Anti-Syphon Frost-Proof Hydrant,” describes a combination drain and anti-siphon valve located at the base of the assembly and extending from one side thereof, allowing water to flow from the barrel after the lower valve has been closed. However, the valve closes when pressure on the outlet side of the valve is higher than the pressure within the empty barrel. Due to the valve stems at each end of the device, it cannot be installed in a dry barrel type fire hydrant with a central control valve rod or stem. Moreover, the Jungbert, Sr. valve is not configured for use in relatively high pressure applications, whereas the present valve is constructed to handle relatively high pressure differentials and large flow volumes.

U.S. Pat. No. 4,763,686 issued on Aug. 16, 1988; U.S. Pat. No. 4,770,203 issued on Sep. 13, 1988; U.S. Pat. No. 4,790,341 issued on Dec. 13, 1988; and U.S. Pat. No. 4,791,952 issued on Dec. 20, 1988, all to David F. Laurel and titled “Hydrant And Components Thereof,” are a series of closely related patents describing numerous detail improvements in fire hydrants. None of the Laurel U.S. patents disclose any form of backflow prevention valve therein.

U.S. Pat. No. 5,129,416 issued on Jul. 14, 1992 to Rand H. Ackroyd, titled “Anti-Siphon Frost-Proof Water Hydrant,” describes a relatively complex water tap for outdoor installation, incorporating two backflow prevention valves and an air inlet. The two valves extend completely across the entire internal cross sectional area of the outlet, with no provision for any form of central control valve rod as is required in a dry barrel hydrant.

U.S. Pat. No. 5,228,470 issued on Jul. 20, 1993 to John E. Lair et al., titled “Self Draining Hose Connection Dual Check Valve Back Flow Preventer,” describes a very complex hose coupling multiple check valves therein. One of the valves has a flexible diaphragm with an opening around the stem of another valve. The two central valves are situated upon central stems, which preclude the use of this type of valve in a dry barrel type fire hydrant with its concentric valve control rod.

U.S. Pat. Nos. 5,590,679 and 5,632,303 issued respectively on Jan. 7 and May 27, 1997 to Lawrence Almasy et al., both titled “Wall Water Hydrant Having Backflow And Back Siphonage Preventor,” are continuations of the same abandoned parent patent application. Both describe a toroidally shaped, flexible elastic valve surrounding a central shaft. Water flow in the desired direction forces the outer edges of the valve to flex inwardly, toward the stem, with water flowing around the outside of the valve, rather than flowing through the center of the outwardly sealed valve as in the present invention. The Almasy et al. valve assemblies appear to be more closely related to the valve assembly of the '470 Lair et al. U.S. patent, than to the present invention.

U.S. Pat. No. 5,971,022 issued on Oct. 26, 1999 to Bunya Hayashi et al., titled “Selector Valve With Counterflow Prevention Means,” describes a pneumatic or hydraulic multiple port valve with a plurality of concentric, one way seals. The seals open along their outer circumferences to allow flow, and flex outwardly to seal about their outer circumferences to block flow in the opposite direction. This configuration appears to be more closely related to the valves of the '679 and '303 U.S. patents to Almasy et al., described further above, than to the present invention.

U.S. Patent Publication No. 2002/144,731 published on Oct. 10, 2002, titled “Hydrant With Improved Drain Mechanism,” describes the installation of a diffuser(s) to the outlet(s) of the drain passage(s) in a dry barrel type fire hydrant. There is no backflow prevention valve provided with the diffuser, nor is any disclosed for the main water passageway of the hydrant.

U.S. Pat. No. 6,561,214 issued on May 13, 2003 to Howard Heil, titled “Hydrant With Improved Drain Mechanism,” is the issued patent based upon the '731 U.S. patent application Publication to the same inventor, discussed immediately above. The same points noted in that discussion are seen to apply here as well.

Finally, Japanese Patent Publication No. 2002-21,123 published on Jan. 23, 2002, titled “Fire Hydrant,” describes (according to the drawings and English abstract) a single, side hinged flapper valve which is held in the closed position by a control rod which bears thereagainst. When the rod is raised, the valve is free to open to allow water to flow. Any back pressure when the valve is open, will push the valve back to its closed position against the seat to prevent backflow. The assembly serves as both the outlet flow control valve and backflow control valve, and would require replacement of the conventional valve in the base of the hydrant assembly for most U.S. hydrants. The outlet directly from the valve is also non-concentric, unlike U.S. hydrants, and cannot be readily adapted for use with U.S. hydrants.

None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a backflow prevention valve solving the aforementioned problems is desired.

SUMMARY OF THE INVENTION

The present backflow prevention valve comprises various embodiments which may be installed in either dry barrel or wet barrel type fire hydrants to prevent the unauthorized back flushing of the hydrant with a contaminated substance, thereby precluding the entrance of such a contaminated substance into the water supply. The present valve embodiments comprise generally cylindrical assemblies having a series of generally triangular segments or leaves pivotally attached to the inner peripheries thereof.

In an embodiment for dry barrel type hydrants, i.e., where the water is drained from the upper barrel when the control valve is closed, the backflow prevention valve segments seal against one another, with their apices sealing against the central control rod or stem for the underlying control valve. In an embodiment for a wet barrel type hydrant, i.e., where the water remains in the barrel due to the control valve being situated at the top of the barrel, the apices of the segments meet one another in the center of the barrel when the water is shut off.

The present backflow prevention valve body may include at least one externally disposed flange for bolting the device between the barrel and the underlying standpipe for the hydrant, with taller embodiments having opposed flanges at each end of the cylinder. A frangible coupling of the appropriate length is also provided for installation along the control rod in dry barrel hydrants, with the coupling also providing a bearing surface for the apex seals of the valve segments of the present invention.

These and other features of the present invention will become readily apparent upon consideration of the following specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an environmental, elevation view of a first embodiment of a backflow prevention valve according to the present invention, installed in an otherwise conventional fire hydrant, riser, and shoe assembly.

FIG. 2 is an elevation view in section of the backflow prevention valve assembly of FIG. 1, showing the internal construction thereof.

FIG. 3 is a detailed broken away elevation view of the hinge detail of a single leaf or vane of the valve of FIG. 2, showing further details thereof.

FIG. 4 is an elevation view in section of a second embodiment of the present invention, configured for installation in wet barrel hydrants having no central control rod or stem.

FIG. 5 is a detailed perspective view of the attachment ring and leaves or segments of the present valve.

FIG. 6 is an elevation view in section of another embodiment of the present invention, in which the body comprises a single relatively thin ring.

Similar reference characters denote corresponding features consistently throughout the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention comprises various embodiments of a completely automatic backflow prevention valve configured to withstand relatively high liquid backflow pressures, yet to allow relatively free liquid flow in the desired direction. It will be noted that the present valve may be incorporated in any of a number of different liquid conduits serving different purposes. However, a primary use of the present valve is envisioned with fire hydrants of various types and configurations, as illustrated in the drawing Figs.

FIG. 1 of the drawings illustrates a fire hydrant installation comprising a barrel B extending concentrically from a standpipe S. The hydrant assembly is conventional, with the exception of the installation of the present backflow prevention valve 10 sandwiched concentrically between the standpipe S and the barrel B. Conventionally, fire hydrant barrels B are secured to their underlying standpipes S by means of a mating circumferential barrel flange BF and standpipe flange SF and a series of peripheral bolts P passing therethrough. This greatly assists in protecting the underlying standpipe S from damage in the event the hydrant barrel B is damaged, e.g. struck by an automobile, etc., by allowing the barrel B to break away from the underlying structure without damage to that structure.

FIG. 2 illustrates further details of the present backflow prevention valve 10. The valve 10 comprises a hollow cylindrical housing or body 12 having an open central area 14 defined by the inner periphery 16 of the housing 12. The housing or body 12 has a first edge 18 and opposite second edge 20 which define a length or height 22 therebetween, with first and second attachment flanges 24 and 26 extending radially outwardly respectively from the first and second edges 18 and 20 of the housing 12. The two flanges 24 and 26 of the housing or body 12 attach respectively to the standpipe flange SF and barrel flange BF by means of the peripheral bolts P. This places the hollow interior 14 of the housing or body 12 in a concentric relationship with the hollow barrel interior BI and standpipe interior SI, to allow liquid to flow freely through the assembly when the conventional lower shutoff or control valve (not shown) is opened.

The housing or body 12 contains a series of rigid, generally triangular valve segments therein, e.g. segments 28a, 28b, 28c, etc., with 28a through 28c being shown in FIG. 2. Any practicable number of valve leaves or segments may be provided for the present invention, as desired. While the perspective view of an exemplary valve embodiment having six leaves or segments is illustrated in FIG. 5 and discussed in detail further below, greater or fewer segments may be provided as desired. Each of the valve segments has a base, e.g. bases 30a, 30b, and 30c shown in FIG. 2, a radially disposed first edge, e.g. first edges 32a, 32b, and 32c in FIG. 2, a radially disposed second edge, e.g. second edges 34a, 34b, and 34c in FIG. 2, and an apex, with truncated apices 36a and 36c being visible in FIG. 2. The first edges 32a, 32b, etc. each mate with an adjacent second edge 34a, 34b, etc. of an adjacent vane 28, e.g. the first edge 32a of the first vane 28a mates with the second edge 34b of the second vane 28b, the first edge 32b of the second vane 28b mates with the second edge 34c of the third vane 28c, etc. around the circular configuration of the assembly. Various mating seals may be provided along these radially disposed edges, with an exemplary configuration being illustrated in FIG. 5 and discussed further below.

FIG. 2 also shows the attachment of the various hinge segments 28a, 28b, etc. within the housing or body 12, with FIG. 3 providing an exploded detail elevation view of this attachment. Each of the segments 28a, 28b, etc. is connected at its base to a flexible hinge 38 which extends inwardly from the inner periphery 16 of the valve housing or body 12. The hinge 38 may comprise a separate component for each valve segment 28a, 28b, etc., or may comprise a toroidal configuration, with each of the valve segments 28a, 28b, etc. being secured to an arcuate portion of the continuously circular flexible hinge 38. The hinge 38 is formed of a resilient material having an outer peripheral valve housing attachment portion 40 and an opposite, inner peripheral valve segment attachment portion 42. A clamp plate or ring 44 having a toroidal configuration seats within a recess 46 formed in the first or lower edge 18 of the housing or body 12, and sandwiches the outer peripheral portion 40 of the flexible, resilient hinge 38 therebetween to secure the hinge 38 in place.

The hydrant configuration illustrated in FIGS. 2 and 3 is that of a “dry barrel” hydrant, i.e. a hydrant having its shutoff or control valve disposed below the hydrant barrel B. When the control valve is opened, water flows upwardly through the valve and into the barrel, thence outwardly through the conventional hose fittings at the top of the barrel. When the control valve is closed, water drains from the barrel B by means of a few relatively small drain passages at the lower end of the barrel B. This prevents water from freezing within the barrel B and damaging the barrel B in below freezing temperatures. Accordingly, the housing or body 12 preferably includes a few such drain passages 48 disposed immediately above the valve assembly 28, one of which is illustrated in FIG. 3, in order to allow water to drain from the barrel B.

As the conventional water shutoff or control valve employed with such dry barrel hydrants is located below the base of the barrel, a control valve rod or stem extends from the operating nut or fixture at the top of the hydrant, down through the interior of the hydrant to the shutoff valve. Such a configuration is shown in FIG. 2 of the drawings. The control valve stem is conventionally formed in two lengths or segments joined by a frangible coupling, in order to preclude damage to the shutoff valve in the event the hydrant barrel B is knocked from its underlying standpipe S. Accordingly, the first and second control valve stem segments S1 and S2 pass concentrically through the standpipe S and barrel B, and are connected in the housing or body 12 by an elongated frangible coupling 50. The coupling 50 is pinned at each end 52 and 54, and includes a weakened, necked down portion 56 to allow breakage at that point 56 in the event the hydrant barrel B is dislodged from its standpipe S. The coupling 50 is of sufficient length to join the two valve stem segments S1 and S2 to compensate for the length or height 22 of the housing 12, with the lengths of the housing 12 and coupling 50 being adjusted to correspond with one another as required.

In the above described dry barrel hydrant configuration, the apices 36a, 36c, etc. bear against the outer circumference of the valve stem coupling 50, rather than forming a sharp apex to seal against one another. Accordingly, the apices of the various valve segments 28a, etc. are truncated for installation in such dry barrel type hydrants, with the truncated apices configured to fit closely against the side of the coupling 50 (or perhaps against the valve stem itself, depending upon the configuration of the assembly). FIG. 3 of the drawings clearly shows such a truncated valve segment tip 36a for the valve segment 28a, with the truncated tip 36a configured to fit closely against the circular shape of the coupling 50 of FIG. 2. It will be seen that some form of resilient seal may be provided to extend from the tip 36a, as required. Such a resilient tip seal is shown in FIG. 5 of the drawings, and discussed further below.

While dry barrel type hydrants are the most prevalent type in use, wet barrel hydrants, i.e. hydrants in which water remains in the upper barrel at all times, may also be found in certain locations. These hydrants have their water control valves situated at the top of the hydrant with water constantly filling the barrel of the hydrant, thus eliminating the need for a long control valve stem assembly. Accordingly, the truncated or relieved valve segment tip shown in FIGS. 2 and 3, is not required for such wet barrel type hydrants. FIG. 4 illustrates a wet barrel hydrant embodiment of the present backflow prevention valve, designated as valve assembly 110. The backflow prevention valve assembly 110 includes a housing or body 112 similar to the housing or body 10 of the dry barrel embodiment of FIGS. 2 and 3, but lacking the drain port(s) 48 of the dry barrel housing 12 shown in FIG. 3. The housing 112 includes an open central area 114 defined by an inner periphery 116, and has opposed first and second edges or ends 118 and 120 defining a length or height 122. First and second attachment flanges, respectively 124 and 126, extend outwardly from the first and second ends 118 and 120.

The valve body or housing 112 contains a series of generally triangular valve leaves or segments, respectively 128a, 128b, 128c, etc., depending upon the number of segments of the valve assembly. Each segment is configured similarly to the valve segments 28a, 28b, etc. of the assembly of FIG. 2, having a base edge 130a, 130b, etc. pivotally extending from the inner periphery 116 of the valve body or housing 112, and first and second radial edges, respectively 132a, 132b, etc. and 134a, 134b, etc. However, the extended point apices 136a, 136b, etc. of the valve segments of the assembly of FIG. 4 differ from the truncated apices 36a, 36b, etc. of the assembly of FIGS. 2 and 3, as there is no central structure running concentrically through the hydrant and housing in a wet barrel type hydrant. Thus, the apices 136 am 136b, etc. come to a relatively sharp point in such a wet barrel hydrant installation and bear against one another when the valve assembly is closed, rather than against a central shaft or coupling. The hinge 138 of the assembly 110 of FIG. 4 may have the same configuration as that of the hinge 38 of the assembly 10 of FIGS. 2 and 3, i.e. a flexible, resilient toroidal having its outer edge secured between the first or lower edge of the housing or body 112 and a toroidal clamping plate or ring 144. The valve leaves or segments 128a, 128b, etc. are pivotally attached to the inboard portion of the hinge 138, and flex upwardly and outwardly toward the inner wall or periphery 116 of the housing 112 when a liquid passes through the assembly from the standpipe S2 to the hydrant barrel B2, just as in the case of the assembly of FIGS. 2 and 3.

FIG. 5 provides a perspective view of an exemplary valve segment assembly 210 for a dry barrel type hydrant, showing the sealing means used along the edges of the valve segments. It will be noted that rather than having a generally cylindrical housing, as in the embodiments of FIGS. 1 through 4, a relatively thin, toroidal ring 212 is provided from which the valve segments extend inwardly. The ring 212 includes an outwardly extending circumferential flange 224 to provide for attachment between the flanges of the standpipe and hydrant barrel, and an inner periphery 216. A series of six generally triangular vanes 228a through 228f are pivotally secured by their bases 230a through 230f along the inner periphery 216 of the ring 212. A flexible, resilient hinge member 238 with a toroidal configuration surrounds the segment bases 230a through 230f, with the outer periphery 240 of the circumferential hinge 238 being secured to the flange 224 adjacent the inner periphery 216 of the ring 212, and the inner periphery 242 folding upwardly and securing to the bases 230a through 230f of the valve segments or leaves 228a through 228f.

Each of the valve segments 228a through 228f includes a first edge, respectively 232a through 232f, an opposite second edge, respectively 234a through 234f, and an apex, respectively 236a through 236f. Each of the mating edges 232a through 232f and 234a through 234f includes means for sealing when the leaves or segments 228a through 228f are closed or folded together, generally as shown in FIGS. 2, 4, and 6. Each of the first edges 232a through 232f includes parallel first and second lips, respectively 58 and 60, which define a groove or channel 62 therebetween. The adjacent mating second edges 234a through 234f each have a convex ridge 64 extending therealong. When the valve leaves or segments 228a through 228f fold together when there is no flow through the hydrant, the ridges 64 of each of the segment first edges 232a through 232f nest within the corresponding groove or channel 62 between the lips 58 and 60 of the adjacent segment second edges 234a through 234f, thereby providing a close seal between mating valve leaves or segments to preclude backflow of liquid therethrough.

The backflow prevention valve 210 of FIG. 5 is configured for use in a dry barrel type hydrant, due to the truncated apices 236a through 236f of each of the valve segments 228a through 228f. Additional apex seals 66 extend from each of the truncated apices, and bear against the central coupling 50 (shown in FIG. 2) when the valve segments 228a through 228f are closed. These apex seals 66, along with the edge sealing lips, grooves, and ridges 58 through 64, provide a reasonably secure seal against backflow through the valve mechanism while still allowing the segments to hinge outwardly against the inner periphery of the backflow prevention valve housing or hydrant barrel, depending upon the valve embodiment employed.

FIG. 6 provides an elevation view in section of another backflow prevention valve assembly 310, installed between a standpipe S and a hydrant barrel B, with the standpipe S and barrel B being essentially identical to the standpipe S and barrel B shown in FIGS. 1 and 2. The backflow prevention valve assembly 310 of FIG. 6 is quite similar to the valve assembly 210 of FIG. 5, comprising a toroidal ring 312 with a circumferentially extending flange 324 which bolts between the flanges F of the standpipe S and hydrant barrel B and is secured in place by peripheral bolts P.

A series of valve segments or leaves extend from the inner periphery 316 of the ring 312, with three of the segments 328a through 328c being shown in the cross sectional view of FIG. 6. The edge and apex seals may be essentially identical to those illustrated in FIG. 5 of the drawings, and discussed further above. However, the flexible hinge 338 is configured differently, with its outer peripheral housing or ring attachment edge 340 extending downwardly along the inner periphery rather than being sandwiched between the circumference of the ring 312 and a circumferential retaining ring, as shown in FIGS. 2 through 5 of the drawings. The inner circumferential portion or edge 342 of the hinge 338 secures to the bases 330a through 330c of the valve segments 328a through 328e, as in the embodiments of FIGS. 2 through 5.

The above described arrangement may be used in either dry barrel or wet barrel type hydrants, with the primary difference being in the configuration of the apices of the valve segments. In FIG. 6, the truncated apices 336a and 336c are shown in solid lines, abutting the central coupling 350. (The coupling need not be so long as shown in FIG. 6 when a relatively thin ring valve configuration is used, but the longer length provides a smooth surface against which the apices of the valve segments may seal.) Where the valve assembly 310 is used in a wet barrel type hydrant without the central control valve stem components S1 and S2, the apices are extended to form mating points, as shown by the apex portions 336a and 336c shown in broken lines in FIG. 6. The sealing means illustrated in FIG. 5 and discussed further above may be incorporated along the edges of the valve segments of the embodiment 310 of FIG. 6, and other embodiments as well.

In conclusion, the present backflow prevention valve in its various embodiments provides a positive, fully automatic means of preventing liquid flow through a conduit in an undesired direction. The present valve may be used in sewage conduits to prevent backups, and/or various other fluid conduit systems as applicable. However, it may find its greatest value in fire hydrant installations, where it will prevent the unauthorized backflushing of hydrants with contaminants, as might otherwise be easily accomplished by terrorists. The present valve is well suited for installation in both dry and wet barrel hydrants, with the primary difference in the valve being the configuration of the valve segment apices to accommodate the central control valve stem in dry barrel hydrants or to mate with one another in wet barrel hydrants.

The present valve is relatively low, and extends the height of a hydrant by only a few inches so as not to exceed any maximum height standards. Where height is even more critical, the ring embodiments of FIGS. 5 and 6 may be employed. While flanges have been illustrated with each of the various embodiments disclosed herein, it will be understood that other conventional means may be used for connecting the present backflow prevention valve with other components, e.g. mating threaded attachments as in pipe fittings, etc.

Any of a number of suitable materials may be used to construct the various components of the present valve embodiments. The outer housing or ring may be cast of iron, similarly to the technique conventionally used for forming fire hydrant barrels, standpipes, and similar components. The vanes must be a relatively stiff material, in order to resist the pressure developed by a high pressure pump in an attempt to induce backflow through the system. Various metals may be used, or alternatively relatively stiff plastics may be used, depending upon the diameter of the valve, the anticipated pressure, and perhaps other factors. The sealing edges and apices may be coated or fitted with relatively softer materials, e.g. Neoprene®, rubber, or other suitable material, in order to provide a water tight seal. Where dry barrel installations are made, the central coupling is preferably formed with a relatively low friction coating to allow the coupling to slide downwardly and upwardly between the apex seals as the operating valve is opened and closed.

Accordingly, the present backflow prevention valve will greatly reduce the risks of contamination to a water supply through a hydrant system, and will prove to be of great value and to greatly improve peace of mind for those responsible for municipal water systems.

It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.

Claims

1. A backflow prevention valve, comprising: a hollow cylindrical body having a first edge, a second edge opposite said first edge defining a length therebetween, and an inner periphery; a plurality of rigid, generally triangular valve segments each having a base, a radially disposed first and second edge, and an apex, the first edge and the second edge of each of said valve segments having a mating, complementary configuration, the first and the second edge of adjacent said valve segments sealing with one another when said valve segments are closed; and at least one flexible hinge extending inwardly from the inner periphery of said body and securing the base of each of said valve segments to said body.

2. The backflow prevention valve according to claim 1, further including: a first attachment flange extending radially outwardly from said first edge of said body; and a second attachment flange extending radially outwardly from said second edge of said body.

3. The backflow prevention valve according to claim 1, further including: a first and a second control valve stem segment passing concentrically through said body; a frangible coupling connecting said first and said second control valve stem segment; said apex of each of said valve segments having a truncated tip; and a seal extending from said truncated tip of each of said valve segments and sealing against said coupling when said valve segments are closed.

4. The backflow prevention valve according to claim 1, wherein: said at least one flexible hinge comprises a resilient material having a toroidal configuration with an outer peripheral body attachment portion and an inner peripheral valve segment attachment portion; and a clamp plate having a toroidal configuration is secured to said first edge of said body, sandwiching said outer peripheral body attachment portion of said at least one flexible hinge between said first edge of said body and said clamp plate.

5. The backflow prevention valve according to claim 1, wherein said apex of each of said valve segments has a pointed tip, bearing against one another when said valve segments are closed.

6. The backflow prevention valve according to claim 1, further including: a first lip and a second lip spaced apart therefrom disposed along said first edge of each of said valve segments, and defining a groove therebetween; and a ridge disposed along said second edge of each of said valve segments, and sealing closely within the mating said groove of an adjacent one of said valve segments when said valve segments are closed.

7. A backflow prevention valve, comprising: a thin ring having a toroidal configuration defining an inner periphery; a plurality of rigid, generally triangular valve segments each having a base, a radially disposed first and second edge, and an apex, the first edge and the second edge of each of said valve segments having a mating, complementary configuration, the first and the second edge of adjacent said valve segments sealing with one another when said valve segments are closed; and at least one flexible hinge extending inwardly from the inner periphery of said ring and securing the base of each of said valve segments to said ring.

8. The backflow prevention valve according to claim 7, further including an attachment flange extending radially outwardly from said ring.

9. The backflow prevention valve according to claim 7, further including: a first and a second control valve stem segment passing concentrically through said ring; a frangible coupling connecting said first and said second control valve stem segment; said apex of each of said valve segments having a truncated tip; and a seal extending from said truncated tip of each of said valve segments and sealing against said coupling when said valve segments are closed.

10. The backflow prevention valve according to claim 7, wherein: said at least one flexible hinge comprises a resilient material having a toroidal configuration with an outer peripheral ring attachment portion and an inner peripheral valve segment attachment portion; and a clamp plate having a toroidal configuration is secured to said ring, sandwiching said outer peripheral ring attachment portion of said at least one flexible hinge between said first edge of said ring and said clamp plate.

11. The backflow prevention valve according to claim 7, wherein said apex of each of said valve segments has a pointed tip, bearing against one another when said valve segments are closed.

12. The backflow prevention valve according to claim 7, further including: a first lip and a second lip spaced apart therefrom disposed along said first edge of each of said valve segments, and defining a groove therebetween; and a ridge disposed along said second edge of each of said valve segments, and sealing closely within the mating said groove of an adjacent one of said valve segments when said valve segments are closed.

13. A hydrant having a backflow prevention valve installed therein, comprising in combination: a hydrant barrel having a hollow interior and a base; a hydrant standpipe disposed concentrically below said barrel; a hydrant backflow prevention valve installed concentrically between said hydrant barrel and said hydrant standpipe, the valve having: a valve housing having an open center concentric with said hydrant barrel and said hydrant standpipe, and having an inner periphery; a plurality of rigid, generally triangular valve segments each having a base, a radially disposed first and second edge, and an apex, the first edge and the second edge of each of said valve segments having a mating, complementary configuration, the first and the second edge of adjacent said valve segments sealing with one another when said valve segments are closed; and at least one flexible hinge extending inwardly from the inner periphery of said valve housing and securing the base of each of said valve segments to said valve housing.

14. The hydrant and backflow prevention valve combination according to claim 13, wherein said valve housing comprises: a hollow cylindrical body having a first edge, a second edge opposite said first edge defining a length therebetween, and an inner periphery; a first attachment flange extending radially outwardly from said first edge of said body; and a second attachment flange extending radially outwardly from said second edge of said body.

15. The hydrant and backflow prevention valve combination according to claim 13, wherein said valve housing comprises a thin ring having a toroidal configuration with an inner periphery.

16. The hydrant and backflow prevention valve combination according to claim 13, further including: a first and a second control valve stem segment passing concentrically through said hydrant barrel, said hydrant standpipe, and said valve housing; a frangible coupling connecting said first and said second control valve stem segment; said apex of each of said valve segments having a truncated tip; and a seal extending from said truncated tip of each of said valve segments and sealing against said coupling when said valve segments are closed.

17. The hydrant and backflow prevention valve combination according to claim 13, wherein: said at least one flexible hinge comprises a resilient material having a toroidal configuration with an outer peripheral valve housing attachment portion and an inner peripheral valve segment attachment portion; and a clamp plate having a toroidal configuration is secured to said valve housing, sandwiching said outer peripheral valve housing attachment portion of said at least one flexible hinge between said valve housing and said clamp plate.

18. The hydrant and backflow prevention valve combination according to claim 13, wherein said apex of each of said valve segments has a pointed tip, bearing against one another when said valve segments are closed.

19. The hydrant and backflow prevention valve combination according to claim 13, further including: a first lip and a second lip spaced apart therefrom disposed along said first edge of each of said valve segments, and defining a groove therebetween; and a ridge disposed along said second edge of each of said valve segments, and sealing closely within the mating said groove of an adjacent one of said valve segments when said valve segments are closed.