FROST-RESISTANT HYDRANT

Abstract: A hydrant (10) has a conduit (12) that communicates with a fluid source at one end thereof and atmosphere at another end thereof. A valve cartridge (100) is positioned in the conduit (12) and includes a cartridge body (104) having a back-flow port (108) and a valve (42) mounted in the cartridge body (104). The valve (42) is movable between an open position allowing fluid flow through the valve (42) to atmosphere in a first direction and a closed position blocking fluid flow. An actuator stem (102) is connected with the valve (42) and extends away from the cartridge body (104) for manipulating the valve (42) between the open and closed positions. The actuator stem has a vacuum breaker port (122) that is axially spaced from the back-flow port (108). A check valve (124) is located in a fluid passage between the vacuum breaker port (122) and the back-flow port (108) for blocking the fluid from flowing through the valve cartridge (100) in a direction opposite to the first direction while permitting fluid flow to atmosphere. The check valve includes a seal member (126) for sealing the back-flow port (108) and a cooperating plunger member (128) for sealing the vacuum breaker port (122). The plunger member (128) is reciprocal with respect to the seal member (126). The plunger member (128) and the seal member (126) simultaneously seal the vacuum breaker port (122) and the back-flow port (108) when the plunger member is extended with respect to the seal member.

Description: FROST-RESISTANT HYDRANT BACKGROUND OF THE INVENTION This invention generally relates to fluid valves and, more particularly, to frost-resistant water supply hydrants. A frost-resistant sill cock or hydrant typically includes an elongated tubular body with a valve mechanism at a first end and with a spout and a valve operator at a second, opposing end. The elongated body allows the valve mechanism to be positioned in an environment where frost or freezing is not likely to occur, such as inside a building or underground, while the spout and valve operator are positioned in a frost- or freezing-prone environment, commonly outside a building or otherwise out-of-doors. Typically, the operator is a handle, and an elongated actuator rod or stem extends within the tubular body between the handle and the valve, whereby manipulation of the handle moves the valve between open and closed positions. A predominant valve mechanism is what may be termed a "plunger valve," wherein a valve plunger or stopper is screw-actuated into and out of sealing engagement with a valve seat. While the plunger valve provides a simple means for controlling flow from a water supply, it does not provide a truly positive control and is prone to damage during closing by over-tightening. That is, rather than screwing the valve plunger into a position of sealing engagement with the valve seat, a user will commonly forcibly close the valve, beyond the point of sealing, mashing and damaging valve seat and plunger sealing surfaces. Further, plunger valves do not readily lend themselves to adaptation for accommodating contemporary health concerns, specifically back- flow prevention, sometimes known as anti-siphoning. Back-flow preventers or anti-siphon devices are desirable to prevent contamination of the water supply caused by siphoning a contaminant back through the hydrant and into the water supply. Plunger-type valves which incoφorate an anti-siphon or back-flow prevention feature are commonly complicated with attendant reduced durability and added expense which often accompany complicated mechanisms. The durability of back-flow prevention and anti-siphon mechanisms may also be compromised by users who over-tighten valves upon closing. Another feature found in contemporary valves is a vacuum breaker. The vacuum breaker will break the "vacuum" in a hydrant which enables siphoning fluid back through the hydrant to the water supply, thereby offering additional anti-siphon protection. The vacuum breaker also offers structural protection to the hydrant in the case of a careless user who leaves a hose connected to the spout or spigot so that the hydrant does not properly drain, but may freeze and rupture. In this instance, the vacuum breaker releases the "vacuum" which holds water in the hydrant in some circumstances, allowing such residual water to drain from the hydrant. The plunger valve does not readily lend itself to the vacuum breaker function which is commonly accomplished with a separate mechanism. U.S. Patent No. 5,392,805 to Chrysler, the subject matter of which is hereby incorporated by reference, has attempted to overcome the above-noted problems by the provision of a frost-resistant hydrant having effective frost- resistance, back-flow prevention or anti-siphon protection, and integrated vacuum breaker protection without the use of conventional plunger valves. The hydrant has a conduit for connection with a fluid source, a valve cartridge positioned in the conduit, and a seal between the valve cartridge and the conduit to block- fluid from flowing between the valve cartridge and the conduit, directing the fluid through the valve cartridge. The valve cartridge has a cartridge body and a valve mounted in the cartridge body. The valve has an open position allowing fluid flow and a closed position blocking fluid flow. The valve cartridge further has an actuator stem extending from the valve for manipulating the valve between the open and closed positions. The stem extends away from the cartridge body. Also, a fluid passage is defmed through the cartridge body, the valve, and the stem. The cartridge body includes a check valve having a seal disk, a first disk seat, and a second seat. The seal disk includes a plunger adapted to abut the second seat in sealing engagement. The seal disk further includes a seal seat adapted to abut the first disk seat in sealing engagement. The seal disk is normally biased by a spring against the first disk seat when the valve is closed. The plunger and disk arrangement is designed to relieve any negative pressure above a certain predefined amount to prevent back-flow from a hose when the valve is open and the water supply turned off. The movement of the plunger to relieve the negative pressure is directly dependent on the movement of the seal disk , which in turn is directly dependent on the force of the spring. However, the spring used to bias the seal disk against the seat requires a very tight tolerance, to provide the proper disk seal against fluid back-flowing into the water supply, and at the same time to permit the disk to unseat when a certain positive pressure is present. Another problem associated with the prior art may occur when the plunger overtravels and becomes lodged in the second seal seat. Even against the spring pressure, the plunger may not unseat to relieve the negative back pressure, and therefore fail to perform in a satisfactory manner. SUMMARY OF THE INVENTION These and other problems of the prior art are overcome by the present invention which provides a valve cartridge having a check valve, an anti- siphon seal disk and a vacuum breaker plunger. The seal disk is adapted to close a back-flow port, and the plunger is adapted to close a vacuum breaker port. According to one aspect of the invention, the plunger includes at one end thereof a seal that slidably and sealingly reciprocates in a coaxial bore extending through the seal disk. A second seal is disposed at another end of the plunger for seating against the vacuum breaker port. A plunger head is located opposite to the plunger one end and is sized to be slidably received within a reduced diameter bore of the vacuum breaker port. An annular stop flange on the plunger head has a diameter greater than the bore to stop plunger movement once the second seal is seated in the vacuum breaker valve seat. According to a further aspect of the invention, the seal disk is biased toward sealing engagement with the back-flow port by a spring. The plunger is axially dimensioned so that when the seal disk is in sealing engagement with the back-flow port, the second plunger seal can be simultaneously seated in the vacuum breaker valve seat. According to another aspect of the invention, a pair of axially extending slots are located in the seal disk to permit water pressure from any back-flow to act against the plunger thereby unseating the plunger from the vacuum breaker port. In this arrangement, unseating of the plunger no longer depends on the spring. Thus, greater tolerance in spring requirements is possible, while significantly improving the vacuum breaker and back-flow operation. These and other objects, features, and benefits of the present invention will be recognized by those skilled in the art, upon further consideration of the specification and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary longitudinal section view of a prior art frost-resistant hydrant. FIG. 2 is a fragmentary longitudinal section view of a valve cartridge according to the present invention. FIG. 3 is a longitudinal section view similar to FIG. 2 with the ceramic valve and stem extension removed, showing the valve cartridge in normal operation when the valve is closed. FIG. 4 is a longitudinal section view similar to FIG. 3 showing the valve cartridge in normal operation when the valve is open. FIG. 5 is a longitudinal section view similar to FIG. 3 showing the valve cartridge in abnormal operation when the valve is open and the inlet is at zero or negative pressure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIG. 1, there is shown a prior art hydrant 10 having a conduit or body tube 12, a seat adapter 14 connected at a first end 16 of body tube 12 for connection with a fluid supply (not shown), such as a water supply pipe, for example, and includes a spout 18 connected at a second end 20 of body tube 12, opposite the first end 16. A valve cartridge 22 is slip-fit into position within body tube 12 and is located near the first end 16. Hydrant 10 also includes a handwheel or operator 24 connected with valve cartridge 22 through the stem extension 47 and actuator stem 40. One end of seat adapter 14 is provided with a cylindrical exterior surface 26 which may be sized for press-fit engagement into conduit end 16, or may be sized for slip-fit engagement and soldering connection with body tube 12. At a second, opposing end of seat adapter 14, external pipe threads 28 and an internal cylindrical bore 30 are provided for either screw or solder connection with the fluid supply. Spout 18 has a cylindrical bore 32 adapted to receive conduit end 20 for press-fit or solder connection. Spout 18 is provided with a hose nipple 34 (shown partially broken away), and internal threads 36 at an end of spout 18 opposite the connection of spout 18 with body tube 12. Valve cartridge 22 includes a cartridge body 38, an actuator stem 40, a valve 42 having a rotating disk 41 and a stationary disk 43, a retainer 44, a cartridge seal 46, and a stem extension 47. The actuator stem 40 operatively connects to the rotating disk 41 of the valve 42 to open and close the valve within a 90-degree rotation. A transverse opening 48 in the actuator stem 40 establishes communication between an interior chamber 50 and a waterway 52 within the body tube 12. The interior chamber 50 includes a back-flow port 54 defined by an annular groove 56 on the interior surface of the actuator stem 40 between the transverse opening 48 and the valve 42 and an O-ring 58 received therein. A sleeve 60 extends between the O-ring 58 and the end of the actuator stem 40 adjacent to the valve 42. An annular stop 62 is disposed in the actuator stem 40 at one end of interior chamber 50 away from the cartridge body 38 and defines a vacuum breaker valve seat 64 at a vacuum breaker port 66. The vacuum breaker port 66 permits communication between the interior chamber 50 and the stem coaxial bore 68. A check valve 70, disposed within the chamber 50 between the O- ring 58 and the vacuum breaker valve seat 64 comprises an anti-siphon seal disk 72 and a plunger 74. The seal disk 72 is adapted to close the back-flow port 54, and the plunger 74 is adapted to close the vacuum breaker port 66. The plunger 74 slidably reciprocates in a coaxial bore extending through the seal disk 72, and has an O-ring 76 disposed in an annular groove at the end thereof extending toward the vacuum breaker valve seat 64. The seal disk 72 is biased toward sealing engagement with the O-ring 58 by a spring 78 extending between the seal disk and the annular stop 62. The O-ring 76 on the end of plunger 72 is adapted to be in sealing engagement with the vacuum breaker valve seat 64. A head 80 on the plunger is spaced away from the O-ring 76 and is received in a recessed seat 82 in the seal disk 72. The head 80 includes an O-ring 84 in sealing engagement with the recessed seat 82. The O-ring 84 is adapted to contact a seal disk flange 86 when the plunger is in its fully extended position. The plunger is axially dimensioned so that when the seal disk is in sealing engagement with the O-ring 58, the O-ring 76 on the end of the plunger will be drawn away from the vacuum breaker valve seat 64 by the interengagement of the head 80 with the seal disk flange 86 through O-ring 84. In this state of normal operation, the valve 42 is closed, and the waterway 52 is in communication with the stem coaxial bore 68 via the transverse opening 48 and the vacuum breaker port 66. In other words, vacuum in the hydrant is broken, and any residual water in the hydrant can exit through the spout 18. When the valve is cracked open as a user begins to rotate the handle, fluid, under pressure, begins to fill the interior chamber 50 and quickly pushes the plunger 74 forward until the O-ring 84 of plunger head 80 contacts the seal disk flange 86 to unseat the seal disk from O-ring 58. The seal disk is pulled forward by the plunger until the plunger is in sealing engagement with the vacuum breaker valve seat 64, thereby closing communication between the stem coaxial bore 68 and the waterway 52. T is sealing action typically occurs before fluid flow enters the waterway 52. Increasing pressure in the interior chamber 50 urges the seal disk 72 against the bias of spring 78 further away from the O-ring and establishes fluid communication between the chamber 50 and the waterway 52. At full flow, the seal disk 72 is urged all the way to the end of the plunger 74, reinforcing the plunger's sealing engagement with the vacuum breaker valve seat 64. In the instance where water pressure is removed, and a vacuum is drawn at the inlet such as in a siphon condition, i.e. when water in a hose connected to the hose nipple 34 backs up into the waterway 52, the seal disk 72 is securely seated against the O-ring 58 due to the pressure from spring 78, and the plunger 74 is normally drawn away from the vacuum breaker valve seat 64 to a point where the O-ring 76 is in sealing engagement with the seal disk 72, thereby preventing fluid flow from the waterway 52 into the interior chamber 50, while at the same time opening communication between the stem coaxial bore 68 and the waterway 52 to break vacuum in the hydrant. In practical use of the above-described arrangement, the material used for the 0-rings 58, 76, and 82 must be very soft to seal the vacuum breaker port during positive water flow at a pressure of less than three psi and before the seal disk 72 leaves the seat at O-ring 58, as required by ASSE 1019 SEC. 3.4. However, the plunger 74 can sometimes become lodged in the vacuum breaker valve seat when subjected to the upper pressure limits as required by ASSE 1019 SEC. 3.10 due at least in part to the softness of the O-ring 76. The plunger depends entirely on the interengagement of the head 80 with the seal disk flange 86 through O-ring 84 to break the vacuum seal. The seal disk in turn depends entirely on the spring 78 to return the seal disk into sealing engagement with the O-ring 58. Thus, when the plunger is lodged in the vacuum breaker valve seat, the spring sometimes does not have enough force to dislodge the plunger for relieving back pressure from any water in the hose. When the plunger refuses to dislodge from the vacuum breaker valve seat, water is free to back-flow from the hose and waterway into the valve cartridge. In this condition, the water cannot drain from the hydrant and may cause internal damage when subject to freezing conditions. When the plunger refuses to dislodge in a negative pressure condition, water is free to back-flow from the hose and waterway, through the open valve, and into the supply line, thereby contaminating the line. The above-described arrangement also requires a tight manufacturing tolerance on the spring 78 in order to permit the plunger to be seated on the vacuum breaker valve seat 64 at the required pressure of three psi, while urging the seal disk against the O-ring 58 when the pressure is relieved. The small space reserved for the spring adds additional limitations to its tolerance. As a consequence, many of the springs being manufactured did not meet the strict tolerance requirements. Referring now to FIG. 2, a fragmentary longitudinal section view of a valve cartridge 100 according to the present invention is shown, wherein like parts in FIG. 1 are represented by like numerals. The valve cartridge 100 includes an actuator stem 102, a valve 42, a retainer 104, and a cartridge seal and cartridge body (not shown) similar to the cartridge seal 46 and cartridge body 38 of FIG. 1. As in FIG. 1, the actuator stem 102 operatively connects to the rotating disk 41 of the valve 42 to open and close the valve within a 90-degree rotation. A transverse opening 48 in the actuator stem 102 establishes communication between an interior chamber 106 and a waterway within the body tube (not shown). The interior chamber 106 includes a back-flow port 108 defined by an annular groove 110 on the interior surface of the actuator stem 102 between the transverse opening 48 and the valve 42. An O-ring 112 is received in annular groove 110. A sleeve 114 extends between the O-ring 112 and the end of the actuator stem 102 adjacent to the valve 42. An annular stop 116 is formed in actuator stem 102 and is defined by a reduced diameter portion 118 at one end of interior chamber 106. A frusto- conical section 120 adjacent to the annular stop 116 defines a vacuum breaker valve seat at a vacuum breaker port 122. The vacuum breaker port 122 permits communication between the waterway (not shown) and the stem coaxial bore 68. A check valve 124, disposed within the chamber 106 between the O-ring 112 and the vacuum breaker valve seat 120 comprises an anti-siphon seal disk 126 and a plunger 128. The seal disk 126 is adapted to close the back-flow port 108, and the plunger 128 is adapted to close the vacuum breaker port 122. The plunger 128 slidably reciprocates in a coaxial bore extending through the seal disk 126, and has an O-ring 130 disposed in an annular groove 132 of a flange section 134. The O-ring 130 is adapted to contact the inner bore surface of seal disk 128 when the plunger reciprocates therein. The plunger flange section 134 engages with an inwardly extending flange 135 of seal disk 126 to prevent separation of the plunger and seal disk. A second O-ring 136 is disposed in an annular groove 138 at a forward section of the plunger. A plunger head 140 located opposite to the flange section 134 is sized to be slidably received within the reduced diameter bore 118. An annular flange 142 on plunger head 140 has a diameter greater than the bore 118 to stop plunger movement once the O-ring 136 is seated in vacuum breaker valve seat 120. Preferably, the annular flange 142 includes a frustro-conical surface 143 adapted to abut against the frustro-conical surface of vacuum breaker valve seat 120. The provision of cooperating structure for stopping the plunger is a significant improvement over the prior art since the plunger can no longer overtravel, and the O-ring is no longer subject to sticking. The seal disk 126 is biased toward sealing engagement with the O-ring 112 by a spring 144 extending between the seal disk and a spring seat 145 of the actuator stem 102. The plunger is axially dimensioned so that when the seal disk is in sealing engagement with the O-ring 112, the O-ring 136 adjacent to flange 142 can seat in the vacuum breaker valve seat 120. A pair of axially extending slots 146 (only one shown) disposed in opposite sides of seal disk 126 permits water pressure from any back-flow to act against flange section 134 and O-ring 130 to unseat the plunger from breaker valve seat 120. This is a significant improvement over the prior art since unseating of the plunger no longer depends on the spring. Thus, greater tolerance in spring requirements is possible, while significantly improving the vacuum breaker and back-flow operation. Although two slots are described in relation to the seal disk, only a single slot or greater than two slots can be provided. The slots may alternatively be located in the plunger and may take any shape desired, as long as the back-pressure unseats the plunger from the vacuum breaker seat. In the state of normal operation, as shown in FIG. 3, valve 42 is closed, seal disk 126 is seated against O-ring 112, and O-ring 136 is seated against vacuum breaker valve seat 120. There is no communication between the waterway and the stem coaxial bore 68 as in the prior art. When the valve is cracked open as a user begins to rotate the handle, fluid under pressure begins to fill the interior chamber 106. Increasing pressure in the interior chamber 106 urges the seal disk 126 against the bias of spring 144 away from O-ring 112 and establishes fluid communication between the chamber 106 and the waterway. At full flow, seal disk 126 is urged against O-ring 136 as shown in FIG. 4, reinforcing the plunger's sealing engagement with the vacuum breaker valve seat 120. Since the plunger is initially in sealing engagement with vacuum breaker valve seat 120, no plunger movement occurs when fluid is introduced into chamber 106. When the fluid pressure drops sufficiently to allow seal disk 126 to return against O-ring 1 12 under spring pressure, as when the valve is closed, the plunger will normally remain seated against the vacuum breaker valve seat 120. If any back pressure is present, i.e. when water in a hose connected to the hose nipple backs up into the waterway, water enters in through slots 146 of seal disk 126 and applies pressure against the plunger flange section 134 and O-ring 130 to drive the plunger away from vacuum breaker valve seat 120, as shown in FIG. 5. This action causes water to flow through stem bore 68 as the plunger head 140 clears the vacuum breaker port 122 until no back pressure remains. The length of the plunger head helps to reduce turbulence over the spring and O-ring during water flow. When back pressure is no longer present, the plunger remains in its unseated position. When the valve is again cracked open as a user begins to rotate the handle, fluid under pressure begins to fill the interior chamber 106 and pushes plunger 128 until O-ring 136 seats against vacuum breaker valve seat 120. This action occurs before seal disk 126 unseats from O-ring 58 to prevent fresh water flow through the stem bore 68. As pressure builds within interior chamber 106, the seal disk is again unseated to establish fluid communication between the chamber 106 and the waterway. This same operation applies in an abnormal condition where water pressure is removed and a vacuum is drawn at the inlet such as in a siphon condition, i.e. when the main water supply is shut of , the valve is open and water in a hose connected to the hose nipple backs up into the waterway. While the invention has been described with reference to its preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereofwithout departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teaching of the invention without departing from its essential teachings.

Claims: -12- CLAIMS The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows. 1. In a hydrant having a conduit adapted to communicate with a fluid source and atmosphere, a valve cartridge positioned in the conduit, the valve cartridge including a cartridge body having a back-flow port and a valve mounted in the cartridge body, the valve being movable between an open position allowing fluid flow through the valve to atmosphere in a first direction and a closed position blocking fluid flow, an actuator stem connected with the valve and extending away from the cartridge body for manipulating the valve between the open and closed positions, the actuator stem having a vacuum breaker port, the cartridge body, valve, actuator stem and conduit defining a fluid passage, a check valve in the fluid passage proximal to the valve cartridge for blocking the fluid from flowing through the valve cartridge in a direction opposite to the first direction while permitting fluid flow to atmosphere, the check valve including a seal member for sealing one of the back-flow port and the vacuum breaker port and a cooperating plunger member for sealing the other of the back-flow port and the vacuum breaker port, the plunger member being reciprocal between a retracted position and an extended position with respect to the seal member, the seal member being positioned between the plunger member and the back-flow port, the improvement comprising: the plunger member and the seal member are adapted to simultaneously seal the vacuum breaker port and the back-flow port when the plunger member is in the extended position. 2. A hydrant according to claim 1 wherein the plunger member is adapted to seal the vacuum breaker port and includes at one end thereof a plunger head that is sized to be slidably received within a bore of the vacuum breaker port. 3. A hydrant according to claim 2 wherein the bore of the vacuum breaker port includes a seat portion and a reduced diameter portion that receives the plunger head, and wherein the plunger member includes a first annular seal and an annular stop flange between the first annular seal and the plunger head, the annular stop flange having a diameter that is greater than the reduced diameter portion of the vacuum breaker port to stop plunger movement once the first annular seal is seated in the seat portion. 4. A hydrant according to claim 3 wherein a coaxial bore extends through the seal member and the plunger member includes at the other end thereof a second annular seal that slidably and sealingly reciprocates in the coaxial bore. 5. A hydrant according to claim 4 wherein a spring extends between the seal member and a portion of the actuator stem to bias the seal member against the back-flow port. 6. A hydrant according to claim 5 wherein the seal member includes at one end thereof an annular rim with a diameter that is smaller than the diameter of the seal member coaxial bore; and the other end of the plunger member includes an annular flange that is adapted to abut the annular rim of the seal member when the plunger member is in the extended position. 7. A hydrant according to claim 6 wherein at least one axially extending slot is located in one of the seal member and plunger member such that fluid pressure from any back-flow of fluid acts against the flange of the plunger member to thereby unseat the plunger member from the vacuum breaker port independent of the spring. 8. A hydrant according to claim 1 wherein the seal member includes a coaxial bore extending therethrough and the plunger member includes at one end thereof an annular seal that slidably and sealingly reciprocates in the coaxial bore of the seal member. 9. A hydrant according to claim 8 wherein the seal member is adapted to seal the back-flow port and a spring extends between the seal member and the actuator stem to bias the seal member against the back-flow port. 10. A hydrant according to claim 9 wherein the seal member includes at one end thereof an annular rim with a diameter that is smaller than the diameter of the seal member coaxial bore; and the one end of the plunger member includes an annular flange that is adapted to abut the annular rim of the seal member when the plunger member is in the extended position. 11. A hydrant according to claim 10 wherein at least one axially extending slot is located in one of the seal member and plunger member such that fluid pressure from any back-flow of fluid acts against the flange of the plunger member to thereby unseat the plunger member from the vacuum breaker port independent of the spring. 12. A check valve for a hydrant, the hydrant having a conduit adapted to communicate with a fluid source, a valve positioned in the conduit, an actuator stem connected to the valve for opening the valve to thereby allow fluid flow therethrough and for closing the valve to thereby block fluid from flowing therethrough, the check valve being located in the conduit between a back-flow port that is in proximity to the valve and a vacuum breaker port spaced axially from the back-flow port, the check va including a first seal member that is reciprocal with respect to the conduit, tne improvement comprising: the first seal member has a stop portion and a seal that is separate from the stop portion, whereby movement of the first seal member is arrested by the stop portion when the seal is seated in one of the back-flow and vacuum breaker ports. 13. A check valve according to claim 12 wherein the first seal member is adapted to seal the vacuum breaker port and includes at one end thereof a plunger head that is sized to be slidably received within a bore of the vacuum breaker port. 14. A check valve according to claim 13 wherein the bore of the vacuum breaker port includes a seat portion and a reduced diameter portion that receives the plunger head, and wherein the seal comprises a first annular seal and the stop portion comprises an annular stop flange between the first annular seal and the plunger head, the annular stop flange having a diameter that is greater than the reduced diameter portion of the vacuum breaker port to stop movement of the first seal member once the first seal is seated in the seat portion. 15. A check valve according to claim 14 and further comprising a second seal member with a coaxial bore extending therethrough, the second seal member being adapted to seal the back-flow port; the first seal member including at the other end thereof a second annular seal that slidably and sealingly reciprocates in the coaxial bore of the second seal member. 16. A check valve according to claim 15 wherein a spring extends between the second seal member and a portion of the actuator stem to bias the second seal member against the back-flow port. 17. A check valve according to claim 16 wherein the second seal member includes at one end thereof an annular rim with a diameter that is smaller than the diameter of the second seal member coaxial bore; and the other end of the first seal member includes an annular flange that is adapted to abut the annular rim of the second seal member when the first seal member is in an extended position. 18. A check valve according to claim 17 wherein at least one axially extending slot is located in one of the first and second seal members such that fluid pressure from any back-flow of fluid acts against the flange of the first seal member to thereby unseat the first seal member from the vacuum breaker port independently of the spring. 19. A check valve according to claim 12 and further comprising a second seal member that is adapted to seal the other of the vacuum breaker port and back-flow port; the first seal member being reciprocally mounted to the second seal member and the second seal member being reciprocal with respect to the conduit; the first and second seal members being adapted to simultaneously seal the vacuum breaker port and the back-flow port when the first seal member is in an extended position with respect to the second seal member. 20. A check valve according to claim 19 wherein the second seal member includes a coaxial bore extending therethrough and the first seal member includes at one end thereof an annular seal that slidably and sealingly reciprocates in the coaxial bore of the second seal member. 21. A check valve according to claim 20 wherein the first seal member is adapted to seal the vacuum breaker port and the second seal member is adapted to seal the back-flow port; and a spring extends between the second seal member and a portion of the actuator stem to bias the second seal member against the back- flow port. 22. A check valve according to claim 21 wherein the second seal member includes at one end thereof an annular rim with a diameter that is smaller than the diameter of the second seal member coaxial bore; and the first seal member includes an annular flange that is adapted to abut the annular rim of the second seal member when the first seal member is in an extended position. 23. A check valve according to claim 22 wherein at least one axially extending slot is located in one of the first and second seal members such that fluid pressure from any back-flow of fluid acts against the flange of the first seal member to thereby unseat the first seal member from the vacuum breaker port independently of the spring.

Inventors: CHRYSLER JIMMIE D, CRESWELL ROBERT S, CHRYSLER, JIMMIE, D., CRESWELL, ROBERT, S.
Applicants: AMERIKAM INC, CHRYSLER JIMMIE D, CRESWELL ROBERT S, AMERIKAM, INC., CHRYSLER, JIMMIE, D., CRESWELL, ROBERT, S.
Application year: 1997
Main classification: E03B9
IPC codes: E03B9, F16K1