Abstract:
An air relief valve for use with an irrigation pipe. The valve comprises a base attached to the wall of the pipe, a vent extending from the interior of the pipe to the exterior of the pipe, a shutoff mechanism, and a water level sensor disposed within the pipe. The vent has an inlet adapted to face the interior of the pipe and an outlet adapted to face the exterior of the pipe. The shutoff mechanism is pivotally articulated to the base between an opening position thereof wherein air can exit the pipe via the vent and a closing position thereof wherein air is prevented from exiting the pipe via the vent. The shutoff mechanism is responsive to the water level sensor to selectively pivot between the opening and the closing positions.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to air relief valves, particularly those adapted for use with irrigation pipes.  
       BACKGROUND OF THE INVENTION  
       [0002]     In large irrigation pipes operating at low pressures, it is common for air to enter therein and become entrapped. This air may be present before the filling and remain trapped, or be present at a much lower volume in water of a higher pressure in the system and expand to a greater volume on entering the low pressure irrigation pipe. Obstructions such as a partially open gate valve may produce cavitations which tend to further expand the entrapped air when the pressure is lowered.  
         [0003]     The air tends to accumulate in large elongated bubbles at points along the pipe which are at higher elevations than adjacent portions (so called local peaks). Since these air pockets cannot move along the pipe, the effective diameter of the pipe in the location thereof is reduced. This may result in turbulent flow of the water in the pipe, as well as in surging and water hammer. Damage or rupture of the pipe may result.  
         [0004]     In order to deal with trapped air, it is known in the art to provide one or more of several types of valves and/or vents, such as air relief/vacuum relief valves, continuous acting air vents (with or without vacuum relief), and pressure relief valves. Such valves/vents are provided, for example, by McMaster-Carr, under the name Air-Release Valve.  
       SUMMARY OF THE INVENTION  
       [0005]     According to first aspect of the present invention, there is provided an air relief valve comprising a base adapted for attachment to the wall of an irrigation pipe, a vent extending through the base from an interior side thereof, adapted to face the interior of the pipe to an exterior side thereof, adapted to face the exterior of the pipe, a water level sensor adapted to be disposed within the pipe at least during use of the vent, and a shutoff mechanism responsive to the water level sensor to open the vent, thereby allowing air to exit the pipe via the vent at least during use, and to close the vent to prevent the air from exiting the pipe via the vent at least during use. The vent has an inlet at the interior side thereof and an outlet at the exterior side thereof, and the shutoff mechanism is movable by the water level sensor between an opening position thereof wherein the inlet of the vent is open for the air from the pipe to pass via the outlet of the vent to the exterior of the pipe, and a closing position thereof wherein the inlet of the vent is closed.  
         [0006]     The water level sensor may have two ends and may be pivotally connected at one end thereof to the base so as to pivot between a first, opening position in which the other end of the sensor is spaced from the wall of the pipe to a first distance, and a second, closing position in which the other end of the pipe is located at a second distance from said wall, which is smaller than said first distance. In this case it may be advantageous if the sensor is connected to the base in such orientation that its second end is located at a location along the pipe downstream of its first end. The valve may comprise an indicium to indicate the orientation at which it should be mounted to the wall of the pipe, to ensure above orientation of the sensor.  
         [0007]     The water level sensor may be in the form of a floatation device adapted to float on water and to be movable between said first and second positions in consequence with the change of the level of water in the pipe.  
         [0008]     According to one embodiment, the vent is in the form of a tube protruding from the base to the interior of the pipe and having a thin-walled portion, and the shutoff mechanism is constituted by the tube being bendable to allow air to exit the pipe via the tube any time except for when the tube is bent to prevent the air from exiting the pipe. In this case, the base may include a rigid tube support portion to support the thin-walled portion of the tube, which may comprise a stationary section, a pivoting section and a bending section therebetween, allowing the pivoting section to pivotally articulate relative to the stationary section, and thereby bend the tube in the area of said bending section, to bring it to said closing position.  
         [0009]     If in this embodiment the water level sensor is in the form of a floatation device, such device may be attached to the pivoting section of the rigid tube support portion of the base to cause this part to pivot and bend the tube in the area of the said bending section, when the water in the pipe reaches a predetermined level.  
         [0010]     According to another embodiment, the vent is in the form of a through-going bore formed in the base and the shutoff mechanism is in the form of a stopper in translational association with the water level sensor, i.e., it is movable by the water level sensor between said opening position in which the stopper is spaced from the inlet of the vent and said closing position in which stopper sealingly bears against the inlet of the vent. The stopper may be formed from a viscoelastic material. The shutoff mechanism may be mounted to the water level sensor or formed as part thereof.  
         [0011]     According to a second aspect of the present invention, there is provided an air relief valve comprising a base adapted for attachment to the wall of the pipe, a vent extending through the base from an interior side thereof, adapted to face the interior of the pipe, to or beyond an exterior side thereof, adapted to face the exterior of the pipe, and a water level sensor, said vent being deformable responsive to the water level sensor, between an opening position allowing, at least during use, air to exit the pipe via the vent, and a closing position to prevent, at least during use, the air from exiting the pipe via the vent.  
         [0012]     The vent may be in the form of a bendable tube to allow air to exit the pipe via the tube any time except for when the tube is bent to prevent the air from exiting the pipe.  
         [0013]     In one embodiment, the tube may protrude from the base to the interior of the pipe and may have a thin-walled portion. In this case, the base may include a rigid tube support portion to support said thin-walled portion of the tube, which may comprise a stationary section, a pivoting section and a bending section therebetween, allowing the pivoting section to pivotally articulate relative to the stationary portion, and thereby bend the tube in the area of said bending section, to bring it to said closing position. If in this embodiment the water level sensor is in the form of a floatation device, such device may be attached to the pivoting section of the rigid tube support portion of the base to cause this part to pivot and bend the tube in the area of the said bending portion, when the water in the pipe reaches a predetermined level.  
         [0014]     In another embodiment, the base may comprise a hollow chamber, with said tube disposed therein. The tube may be disposed in the chamber in a bent position and have a stationary tube section, a pivoting tube section and a bending tube section therebetween, the pivoting section being adapted to pivotally articulate relative to the stationary section by the deformation of the bending section. If in this embodiment the water level sensor is in the form of a floatation device, such device may be also disposed within the chamber to bear against the pivoting tube section, thereby causing the tube to bend when the water in the pipe reaches a predetermined level.  
         [0015]     The water level sensor does not necessarily have to be in the form of a floatation device but may be in any other form capable of bending the tube.  
         [0016]     According to a further aspect of the present invention, there is provided a direction indicator for use in a valve to allow proper orientation thereof inside an irrigation pipe.  
         [0017]     According to a still further aspect of the present invention, there is provided an irrigation pipe comprising a float and an opening located in proximity thereto, the pipe being adapted for introduction into an irrigation main.  
         [0018]     The irrigation main may be a flexible pipe.  
         [0019]     The opening may be formed such that is passes through the float or in the pipe substantially adjacent thereto. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:  
         [0021]      FIG. 1  is a perspective view of an air release valve according to one embodiment of the present invention;  
         [0022]      FIG. 2  is a front view of the valve illustrated in  FIG. 1 ;  
         [0023]      FIG. 3  is a close-up view of the area indicated at ‘A’ in  FIG. 1 , from a slightly different perspective;  
         [0024]      FIGS. 4A and 4B  illustrate the valve of  FIG. 1  installed in a pipe, during different states of fill thereof;  
         [0025]      FIGS. 4C and 4D  are cross-sectional views of a tube, being part of the valve illustrated in  FIG. 1 , taken along line II-II in  FIG. 2 , in open and closed positions, respectively;  
         [0026]      FIG. 5  is a cross-sectional view of an air release valve, in an open position, according to another embodiment of the present invention;  
         [0027]      FIG. 6  is a top view of a base of the valve illustrated in  FIG. 5 ;  
         [0028]      FIG. 7  is a partial back view of the valve illustrated in  FIG. 5 ;  
         [0029]      FIG. 8  is a cross-sectional view of the valve illustrated in  FIG. 5 , in a closed position;  
         [0030]      FIGS. 9A and 9B  illustrate the valve of  FIG. 5  installed in a pipe, during different states of fill thereof;  
         [0031]      FIG. 10  illustrate an air release valve, according to a further embodiment of the present invention;  
         [0032]      FIG. 11  is a cross-sectional view of the valve illustrated in  FIG. 10 , taken along line IV-IV;  
         [0033]      FIG. 12  is a cross-sectional view of the valve illustrated in  FIG. 10 , taken along line VII-VII;  
         [0034]      FIG. 13  is a cross-sectional view of the valve illustrated in  FIG. 10 , taken along line IV-IV, shown during use in a closed position; and  
         [0035]      FIGS. 14A and 14B  are cross sectional views of an irrigation pipe according to two examples of a simplified arrangement of the present invention. 
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0036]      FIGS. 1, 2  and  3  illustrate one example of an air relief valve, generally designated at  10 , in an open position. The valve  10  has a longitudinal axis X and is adapted for installation in the wall of an irrigation pipe with the axis X forming an angle with the wall, as shown in  FIGS. 4A and 4B . The pipe may be any known flexible pipe, such as that disclosed in US 2004-0222321 A1 to the present applicant, the Detailed Description of which is incorporated herein by reference.  
         [0037]     As better seen in  FIG. 2 , the valve  10  comprises a vent tube  2  having an inlet section  3 , an outlet section  4 , and an intermediate section  5  therebetween with a thin-walled section  6 . The thin-walled section  6  has an external diameter essentially less than that of the adjacent thick-walled portions  7  and  9  of the intermediate section  5  of the vent tube.  
         [0038]     The valve further comprises a rigid tube support portion  11  supporting the intermediate section  5  of the vent tube  2 , a base portion, generally indicated at  8 , mounted on the outlet section  4  of the vent tube  2 , and a float  34  mounted on the inlet portion  3  of the vent tube  2 . The vent tube  2  together with the rigid tube support portion  4  may be produced by injection molding, with the base section  8  and the float  34  being molded over the respective inlet and outlet sections  3  and  4  thereof. The base section and the float are made of a material which is substantially non-absorbent and is less dense than water.  
         [0039]     The base portion  8  comprises a flange  16 , adapted for being pressed to the inner surface of the wall of the irrigation pipe, and a cylindrical end-piece  20  adapted to protrude from the outer surface of the wall, when the valve is installed therein and to be held by user&#39;s hand or tool during the installation, as will be explained in more detail later.  
         [0040]     As best seen in  FIG. 2 , the vent tube  2  has a tubular passageway  22  extending all along the valve and having an inlet  13  in the float  34  and an outlet  15  in the cylindrical end-piece  20 .  
         [0041]     The rigid tube support portion  11  comprises a stationary section  12 , a free section  14 , and a bending section  15  therebetween in the form of a living hinge, allowing the free section  14  to be pivotally articulated relative to the stationary section  12  about an axis perpendicular to the longitudinal axis X of the valve. The stationary section  12  of the rigid supporting portion  11  accommodates the thick-walled portion  7  and a part  6 ′ of the thin-walled section  6  of the vent tube  2 , and it merges with the base portion  8 . The free section  14  of the rigid supporting portion  11  accommodates the thick-walled portion  9  and a part  6 ″ of the thin-walled section  6  of the vent tube  2 , and it merges with the float  34 . The bending section  15  of the rigid support portion  11  is formed with aperture  19  extending along the thin-walled portion  6  of the vent tube so that, when the free section  14  is articulated relative to the stationary section  12  thereof, the thin-walled section  6  may deform outwardly when bent in the vicinity of bend-area  17  wherein parts  6 ′ and  6 ″ merge.  
         [0042]      FIG. 4A  illustrates the valve  10  in its open position, mounted to the wall  40  of an irrigation pipe  42 , for instance in a local peak thereof (where trapped air will accumulate). This may be accomplished either before the pipe is filled or after. In the latter case, the water supply should be shut off before the installation. A hole, having a diameter smaller that that of the end-piece  20 , is formed in the pipe. Before insertion, the valve  10  may be bent and re-straightened, in order to create an initial bend-line in the bending section  15  of the rigid tube support portion  11  of the vent tube  2 . The valve  10  is inserted through the hole, free-portion  14  first. The flange  16  is forced through the hole, and then the valve  10  is pulled back so that the flange bears against the interior side of the wall of the pipe. The internal pressure of the irrigation pipe  42  creates a seal between the flange  16  and the interior side of the wall of the pipe.  
         [0043]     Upon filling of the pipe, as seen in  FIG. 4A , a large quantity of air may accumulate above the water  44 . In the absence of any venting means, the effective diameter of the pipe in the location of the air is D 1 . In this state, the free portion  14  of the valve  10  hangs, keeping the vent tube  2  in an open position. Air can therefore exit the pipe  42  by entering the inlet  13  of the vent tube  2  along the path indicated by arrows  46 , and exiting the outlet  15  thereof along the path indicated by arrows  48 . As seen in  FIG. 4B , as the air is vented, the level of water  44  rises, which raises the float  34 , pivoting the free portion  14  thereof, and bending the thin-walled section  6  of the vent tube  2  until it seals itself by kinking (i.e., the section  6  of the tube  2  deforms along the bend-area  17  thereof until the cross sectional shape of the tube becomes linear, as illustrated in  FIGS. 4C and 4D ). The effective diameter of the pipe in the location of the air is thereby increased to D 2 .  
         [0044]     It will be appreciated that the vent tube  2  is to be made of a material which can withstand such bending without rupture, such as from polypropylene or polyethylene.  
         [0045]     During use of the pipe, it is normal for additional air to become trapped therein. As this occurs, the level of water in the vicinity of the valve  10  lowers, causing the free portion  14  thereof, and the float  34  carried thereby, to fall. The vent tube  2  opens, allowing excess air to escape. As the air escapes, the level of water rises, resealing the tube.  
         [0046]     Thus, in operation, the float  34  with the free portion  14  constitutes a water level sensor  41  of the valve, which has a free distal end  43  and a proximal end  45  with which the sensor is pivotally connected to the stationary portion  12 , the latter together with the base portion  8 , constituting the valve&#39;s base  45 . The water level sensor  41  thus pivots between a first, opening position in which the distal end  43  thereof is spaced from the wall  40  of the pipe  42  to a first distance d 1 , and a second, closing position in which the distal end  43  is located at a second distance d 2  from the wall  40 , which is smaller than the first distance d 1 .  
         [0047]     In order to safeguard against the water preventing the free portion  14  from pivoting upward, the valve  10  may be installed such that the distal end  43  of its water level sensor  41  is downstream from its proximal end  45 , as seen in  FIGS. 4A and 4B  (with the direction of water flow being indicated by arrow  50 ).  
         [0048]     It will be appreciated that it is not sufficient that the water level sensor  41  be designed so that the buoyant force thereof when submerged in water is sufficient to raise itself, but the buoyant force must also sufficient to bend the vent tube  2 , and keeping the distal end  43  of the water level sensor above the surface of the water.  
         [0049]      FIG. 5  illustrates another example of an air relief valve, generally indicated at  100 . The valve comprises a base body  102  and a water level sensor in the form of a float  104  having a distal end  103  spaced from the body  102  and a proximal end  107  at which the float is pivotally articulated to the body  102  about axle  106 .  
         [0050]     The body  102  is adapted to be attached to the wall of a pipe. It comprises a vent  108  open to a key-receiving portion  110 . As best seen in  FIG. 6 , the key receiving portion  110  is in the form of a regular hexagon, and is adapted to receive therein a standard allen-type key wrench. The body  102  further comprises a float support  112  adapted to receive therewithin the axle  106 . As seen in  FIG. 7 , the float support  112  comprises two legs  112   a  and  112   b , adapted to receive therebetween the float  104 . It will be appreciated that while the float  104  is illustrated in  FIG. 7  as having a narrow portion adapted to be received within the legs  112   a ,  112   b  and a wide portion, the entire length of the float may be of the same thickness as the portion received within the legs.  
         [0051]     The float  104  is adapted to float on water, and comprises a stopper  114  on an upper surface thereof. The stopper  114  is located such that when the float  104  is in a horizontal position against the bottom of the base  102  (see  FIG. 8 ), it bears against the bottom of the vent  108 , thereby sealing it. It is made from a material adapted to hermetically seal the vent  108 , such as a viscoelastic material. The stopper  104  may be a distinct piece securely held to the float  104 , or it may be integrally formed therewith. Alternatively, the float  104  may be covered with a tight-fitting sheath (not shown) comprising a portion adapted to serve as the stopper.  
         [0052]     In operation, as illustrated in  FIGS. 9A and 9B , the valve  100  is mounted to the wall of an irrigation pipe  116 , for instance in a local peak thereof (where trapped air will accumulate). Upon filling of the pipe, as seen in  FIG. 9A , a large quantity of air accumulates above the water  118 . In the absence of any venting means, the effective diameter of the pipe in the location of the air is D 1 . In this state, the float  104  hangs, keeping the vent  108  open to the pipe. Air can therefore exit the pipe  116  by entering the vent  108  along the path indicated by arrows  120 , and exiting along the path indicated by arrows  122 . As seen in  FIG. 9B , as the air is vented, the level of water  116  rises, which raises the float  104 , and pivoting it until it seals the vent  108 . The effective diameter of the pipe in the location of the air is thereby increased to D 2 .  
         [0053]     During use of the pipe, it is normal for additional air to become trapped therein. As this occurs, the level of water in the vicinity of the valve  100  lowers, causing the float  104  the fall. The vent  108  is opened, allowing excess air to escape. As the air escapes, the level of water rises, causing the float  104  to rise and recluse the vent  108 .  
         [0054]     In order to safeguard against the normal flow of water, and especially the in-rush of new water during filling of the pipe, from causing the float  104  from pivoting upward, the valve  100  may be installed such that the distal end  103  of the float  104  is located downstream from the proximal end thereof, as seen in  FIGS. 9A and 9B  (with the direction of water flow being indicated by arrow  124 ). In order to align the valve  100  after it is installed, an allen-type key wrench may be inserted in the key receiving portion  110  in order to rotate the valve. It will be appreciated that the key receiving portion  110  may be replaced by any other feature which can receive therein a tool adapted to imparting a torque, such as a recess (not shown) adapted to receive a Phillips-head or flat-head screwdriver, or a custom tool. Reverting to  FIG. 6 , an indicium  128 , such as in the form of an arrow, may be provided to indicate the preferred direction of installation (as illustrated in  FIG. 6 , the indicium indicates the downstream direction of the pipe).  
         [0055]     Among the advantages of the above examples is the possibility of being mounted on a lay-flat type pipe, having relatively thin walls, after having been deployed and still have a sensor to float within the pipe.  
         [0056]      FIG. 10  illustrates a third embodiment of an air release valve, generally designated at  200 . The valve  200  comprises a housing having a main portion  202 , a shoulder  204 , and a neck  206  therebetween. The neck  206  is adapted to receiver the wall of the pipe when installed.  
         [0057]     As seen in  FIG. 11 , the main portion  202  of the housing defines therein a hollow main chamber  208 , which is bounded at the top by an upper wall  210 . A bent flexible conduit  212 , constituting a vent, is provided within the chamber  208 , having a proximal, stationary portion  213 , bearing against the wall  210 , a distal, free portion  215  hanging within the main chamber  208 , and a bending portion  217  therebetween. The conduit is made such that when it is bent at the bending portion  217 , air or other fluids cannot pass the location of bending. This may be accomplished, e.g., by constructing the conduit  212  from a thin-walled material with polymer chains oriented along the length thereof.  
         [0058]     The conduit  212  is open at a proximal end  214   a  thereof to the exterior of the valve  200 , and at a distal end  214   b  thereof to the interior of the main chamber  208 . The main chamber  208  is open at the bottom. Three legs  216  are provided there, protruding inwardly from the interior surface of the neck  206  (see  FIG. 12 ).  
         [0059]     A water level sensor in the form of a ball  218 , adapted to float on water, is provided within the main chamber  208 . The ball  218  is of a diameter such that it cannot pass between the three legs  216 . When the ball  218  rests in a neutral position on the legs  216 , the hanging portion of the conduit  212  bears against it. Air is thus free to exit the valve by entering the conduit  212  at its distal end  214   b , e.g., along the path indicated by arrow  220 , and exiting the conduit, as indicated by arrow  222 , from the proximal end  214   a  thereof.  
         [0060]     As illustrated in  FIG. 13 , the valve  200  may receive a pipe wall  224  on its neck  206  for mounting thereon. The valve  200  is place at a point on the pipe which is at a local peak thereof (where trapped air will accumulate). As the air accumulates, it exits the valve  200  as described above. When most of the air has been released, water  226  begins to enter the main chamber  208  of the valve, as indicated by arrows  228 , lifting the ball  218 . The hanging portion of the conduit  212  rises with the ball  218 , causing it to bend further, thereby sealing itself at the point of bending  230 .  
         [0061]     During use of the pipe, it is normal for additional air to become trapped therein. As this occurs, the level of water in the vicinity of the valve  200  lowers, causing the ball  218 , and as a result the hanging portion of the conduit  212 , to fall. The conduit  212  opens, allowing excess air to escape. As the air escapes, the level of water rises, causing the ball  218  to rise, raising the hanging portion of the conduit  212  until it closes itself.  
         [0062]     Some of the advantages of the above examples may further be realized in a simplified arrangement, as illustrated in  FIGS. 14A and 14B . An irrigation pipe  60 , having outlets (not shown) as known in the art, such as drippers, sprinklers, etc., is provided at one end with a float  62  and an opening  64  close to (as in  FIG. 14A ) or integral with (as in  FIG. 14B ) the float. The pipe  60  is inserted into an irrigation main  66  at a location where it is determined that air may or has accumulated. A connector  68  is provided in order to ensure than no water leaks out at the point of connection.  
         [0063]     During use, the float  62  keeps the opening  64  at or near the top of the level of the water within the irrigation main  66 . As air accumulates within the irrigation main  66  in the vicinity of the pipe  60 , it is released via the pipe and exits through the openings. When all of the air has been thus dispelled, water continues to flow through the pipe  60  to the openings.  
         [0064]     Those skilled in the art to which this invention pertains will readily appreciate that numerous changes, variations and modifications can be made without departing from the scope of the invention mutatis mutandis.