Abstract:
A water supply system is described for supplying water to a linearly moving irrigation system. The water supply system is able to take water from a stationary water supply conduit (either a collapsible conduit or a rigid conduit) and feed it into one end of a feed pipe for the irrigation system. The water supply system includes a pickup shoe which extends into the water supply conduit through a traveling opening in the top side of the conduit. The pickup shoe intercepts substantially all of the water in the supply conduit and pumps it upwardly through the traveling opening to the feed pipe for the irrigation system. The pump is located in the portion of the shoe which extends into the supply conduit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of my application Ser. No. 11/445,705, filed Jun. 2, 2006 now abandoned, which is based upon, and claims priority from, my Provisional Application No. 60/688,117, filed Jun. 7, 2005. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to field irrigation systems. More particularly, this invention relates to linearly moving sprinkler systems. Even more particularly, this invention relates to water supply systems for supplying water from a stationary conduit at a continuously changing location to a linearly moving sprinkler irrigation system. 
     BACKGROUND OF THE PRIOR ART 
     Efficient irrigation of large fields with sprinklers requires that a relatively small number of sprinkling nozzles be moved over the field. One method of accomplishing this is to mount these nozzles on an overhead moving pipeline. The most prominent system now in use is called a center pivot and consists of an overhead pipeline supported by towers on wheels. The overhead pipeline rotates about a fixed point called the pivot. Water is supplied to the pipeline at this fixed pivot point and flows radially outward to the nozzles mounted on the pipeline. The resulting paths taken by the nozzles are concentric circles. Disadvantages of the center pivot system are adapting the circular pattern to square or rectangular fields and the fact that each nozzle travels at a rate proportional to its distance from the pivot point and must therefore be individually calibrated such that the rate of water application is as uniform as possible over the entire field. 
     Linear systems, sometimes called lateral move systems, also consist of an overhead pipeline supported by towers on wheels. Linear systems move perpendicular to the axis of the pipeline such that all points on the pipeline move at the same rate. Linear systems alleviate the two listed disadvantages of the center pivot system because their spraying patterns are rectangular and each nozzle sprays at the same rate, but they create another problem of their own. This problem is getting the supply water into the moving linear irrigation system. Because of this problem and the high cost of overcoming it with existing technology, linear systems are not now as widely used as are center pivot systems. 
     In general, there are two methods that are now in use to get supply water into a moving linear irrigation system. They are the ditch feed method and the hose drag method. The ditch feed method requires that there be an open ditch adjacent to or through the field carrying more water than is needed to irrigate the field. For the great majority of fields, this is not feasible, so that the hose drag method is now the most prevalent method of getting supply water into a moving linear irrigation system. A hose drag system consists of a hose attached at one end to a fixed hydrant and at the other end to the moving overhead pipeline system. The hose is doubled back on itself with a 180° bend so that it can accommodate the changing distance between the fixed hydrant and the moving overhead pipeline. 
     Hose drag systems are cumbersome and expensive. The length of hose that can be dragged is limited by the traction of the drive wheels of the linear irrigation system and this limit is generally less than desired. Thus, more than one hydrant is needed, which requires additional underground pipelines to the additional hydrants. Switching from one hydrant to the next is a significant chore that requires a shut-down of the system while the hose is dragged to the next hydrant. To accommodate the high flow rates necessary to irrigate large fields, the hose must be relatively large in diameter and therefore heavy when filled with water. Forces required to drag it are substantial. The hose itself must be strong enough to transmit these forces. The hose must also be flexible and resistant to wear. A smooth strip of land at least twice as wide as the minimum bending radius of the hose must be provided for dragging the hose, and this strip of land cannot otherwise be utilized. Clearly, there is a need for a better system for getting supply water to a moving linear irrigation system. 
     In 1971 U.S. Pat. No. 3,592,220 (Reinke) was issued for a LINEAR IRRIGATION SYSTEM WITH PICKUP SHOE. The patent discloses a system for withdrawing fluid from a stationary closed conduit at a continuously changing location in order to supply a linear irrigation system. However, a system using the concept disclosed in the patent is not available on the market. 
     In the aforementioned Reinke patent, it appears that the water conduit 104 must be rigid, and the water in the conduit must be pressurized in order to keep the slit closed in the top of the conduit. It further appears that the water pressure in conduit 104 is substantially the same along the full length of that conduit, both upstream and downstream from the pickup shoe 94. Another disadvantage of the Reinke system is that a peripheral seal 102 is required which is external to the conduit and extends the length of the pickup shoe. The seal is subject to leakage whenever the pickup shoe and the conduit are not in perfect alignment. 
     In 1980 U.S. Pat. No. 4,219,043 (Zimmerer et al.) was issued for Continuous-Feed Fluid Supply Apparatus. The patent describes apparatus for supplying water or other fluids from a stationary pipe to a moving pipe. A system using this concept is not available on the market. The stationary supply conduit has a seam which can be opened and closed somewhat like a zipper. An extractor is located inside the supply conduit and has a riser portion which protrudes through an opening in the seam. The extractor includes a generally cylindrical body portion. There is no description of a pump in the tube for pressurizing the water and pushing it upwardly. Apparently in Zimmerer&#39;s system the water pressure in the supply conduit is responsible for pushing the water out through the riser portion. This would normally preclude the use of thin-walled plastic conduits. 
     Other patents that disclose traveling openings in closed conduits are U.S. Pat. Nos. 3,903,917 (Ede); 3,011,502 (Jordan); 3,019,813 (Dormann); 2,974,876 (Poynor); and 4,576,335 (McAberg). None of these systems appear to have been commercialized, possibly due to leakage past the seals. 
     Another type of prior art includes the technology previously used in designs for closing plastic bags and is marketed under trade names such as ZIPLOC, HEFTY ONE, ZIP, GLAD LOCK, and others, and it is disclosed in numerous patents including U.S. Pat. Nos. 4,212,337; 3,173,184; 5,664,299; and many others. 
     There has not heretofore been provided a moving linear irrigation system which is able to effectively and efficiently remove water from a low pressure supply conduit and use that water in a moving sprinkler apparatus. 
     SUMMARY OF THE INVENTION 
     The present invention provides apparatus and techniques to get supply water from a fixed location such as a well or hydrant to a moving linear irrigation system in an economical and convenient manner. Water from the fixed location is directed to a stationary water conveyance system, i.e. a closed conduit. The stationary water conveyance system has a traveling opening such that a pressurizing pickup shoe mounted on a moving linear irrigation system can extend down through the traveling opening in the stationary water conveyance system to take water from that system. The pressurizing pickup shoe comprises (1) an inlet for intercepting the water in the stationary water conveyance system (i.e. a conduit), (2) a seal (preferably around the periphery of the portion of the pickup shoe which is inside the conduit) for maximizing the amount of water intercepted and for separating that portion of the conduit containing water from the downstream portion that should be empty; (3) a pump for pressurizing the water in the pickup shoe; and (4) a suitable channel (i.e. a neck or riser portion) for passing the water up through the traveling opening into the moving linear irrigation system. The channel can be shaped to conform to the shape of the traveling opening in the stationary water conveyance system (i.e. conduit). The channel must contain a compartment for getting power down to the pump and must furnish structural support for the pump, the pump motor and the rest of the pressurizing pickup shoe. 
     The first embodiment of the present invention utilizes a thin-walled flexible and collapsible plastic tube for the stationary water conveyance system (i.e. the water conduit). The thin-walled plastic tube has a longitudinal slit running the length of the tube, and the slit is closed with a long adaptation of a reclosable fastener assembly such as those used to open and close small plastic household containers and know by tradenames such as ZIPLOC, HEFTY ONE ZIP, GLAD.LOCK or other similar identities. 
     A second embodiment of the invention uses a rigid stationary closed conduit with a slit running the length of the rigid stationary closed conduit. The slit is held in a normally closed position by spring forces that are either built into the wall of the stationary closed conduit or press against the external wall of the stationary closed conduit. The flattened and streamlined neck or riser portion of the pressurizing pickup shoe has a wedge shape on each end that pries open the slit as the linear irrigation system moves along the slitted rigid stationary closed conduit. Flanges extending radially outward can be provided on both sides of the slit, both to facilitate the prying and to assist in sealing the slitted rigid stationary closed conduit against leakage. 
     In addition to supplying water to a linearly moving sprinkler irrigation system, the invention may also be used to supply water to high pressure squirt guns, thereby replacing the costly heavy duty hose reels now in use. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates the most common prior art method now in use for getting supply water to a linear irrigation system. Typically the four-wheel cart shown in  FIG. 1  will have a platform on which an engine, generator or oil pump and various panels and controls are mounted, but the platform and items mounted thereon are not shown here for reasons of clarity. 
         FIG. 2  is similar to  FIG. 1  except that the present invention is used for getting supply water to the linear irrigation system. 
         FIG. 3  is a cross-sectional view of a thin-walled flexible conduit taken along line  3 - 3  of  FIG. 2 , where the conduit is filled with water. 
         FIG. 4  is a cross-sectional view of a thin-walled flexible conduit taken along line  4 - 4  of  FIG. 2  after the water has been removed by a pressurizing pickup shoe. 
         FIG. 5  is an enlarged view of the pressurizing pickup shoe. 
         FIG. 6  is a perspective view of that portion of the pressurizing pickup shoe that would remain after a longitudinal cut along the center line of the pressurizing pickup shoe. 
         FIG. 7  is a plan view of that portion of the pressurizing pickup shoe that would remain after a horizontal cut through the flattened and streamlined neck of the pressurizing pickup shoe. 
         FIG. 8  is a perspective view of that portion of the pressurizing pickup shoe that would remain after a lateral cut along plane  8 - 8 , as indicated by line  8 - 8  on  FIG. 7 . 
         FIG. 9  is a perspective view similar to  FIG. 8  except that  FIG. 9  illustrates the connection apparatus necessary when a press fit type of closure fastening device is utilized. The location of the lateral cut of  FIG. 9  is indicated by line  9 - 9  in  FIG. 7 . 
         FIG. 9A  is an enlarged view of a portion of the cross-sectional cut of  FIG. 9  illustrating the guideways that hold the closure fastening device while it is disengaged. 
         FIG. 9B  is an enlarged view of a portion of  FIG. 9  that illustrates the roller mechanism that is used to open and close the closure fastening device. 
         FIG. 10  illustrates a prior art type of closure fastening device from U.S. Pat. No. 4,212,337 that can be utilized in the present invention. 
         FIG. 11  illustrates another type of prior art closure fastening device from U.S. Pat. No. 5,664,299 that can also be utilized in the present invention. 
         FIG. 12  is similar to  FIG. 11  except that a modification has been made wherein the walls of the zipper profile extend in opposite directions from the slider. 
         FIG. 13  is similar to  FIG. 7  except that  FIG. 13  illustrates the pressurizing pickup shoe needed for the second embodiment of the invention which utilizes a rigid stationary closed conduit in place of the flexible and collapsible stationary closed conduits of embodiment one.  FIG. 13  is a plan view of that portion of a specially adapted pressurizing pickup shoe that would remain after a horizontal cut through the neck of the pressurizing pickup shoe. 
         FIG. 14  is a cross-sectional view of a rigid stationary closed conduit as utilized in the second embodiment of the invention. The cross-section is taken along line  14 - 14  in  FIG. 13 . 
         FIG. 15  is a cross-sectional view of a rigid stationary closed conduit taken at a location where the rigid stationary closed conduit is pried open by the pressurizing pickup shoe as indicated by line  15 - 15  on  FIG. 13 . 
         FIG. 16  illustrates a method for assembling the rigid stationary closed conduit utilized in the second embodiment of the invention to get the necessary pre-stressing forces for holding the seam closed. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a prior art technique and system for getting water into a linear irrigation system and sprayed onto crops. Water from hydrant  11  enters hose  12 , which is connected to cart  13  at either point  14   a  or  14   b . The water then flows up vertical feed pipe  15  to a swivel connection  16 , thence out into a main water line  17 . The water then flows down through drops  18  to nozzles  19  where it is sprayed onto the crops. Swivel connection  16  enables the main line to be rotated 180° so that crops on the opposite side of cart  13  can be irrigated. The main water line  17  is supported by truss structure  20 . Cart  13  has drive wheels  21  which propel the cart  13  down the field, dragging one end of hose  12  along with it. 
       FIG. 2  illustrates how the present invention connects with the sprinkler apparatus of the type shown in  FIG. 1 . Water is directed into stationary closed conduit  22 . Conduit  22  has a traveling opening  23  that moves together with cart  13  such that the traveling opening  23  remains directly under cart  13 . A pressurizing pickup shoe  24  extends through traveling opening  23  into conduit  22 . Pressurizing pickup shoe  24  picks up water from the conduit  22 , pressurizes it, and directs it out through traveling opening  23  into vertical pipe  15 . The water then proceeds onto the crops in the same manner as in the system described and illustrated in connection with  FIG. 1 . 
       FIG. 3  illustrates an approximation of a typical cross-section of stationary closed conduit  22  at points between the water source and cart  13  where the conduit is full of water. Conduit  22  can be a thin-walled flexible plastic tube which has a generally flat or planar bottom surface, as shown. Conduit  22  has a longitudinal seam  25  that runs the length of the conduit  22 . Longitudinal seam  25  is an adaptation of any one of numerous reclosable fastener assemblies of the prior art such as those used to open and close small plastic household containers and are known by trade names such as “Ziploc”, Hefty One Zip, GLAD.LOCK, or similar identities. Longitudinal seam  25  is normally closed but can be opened to create traveling opening  23 . 
       FIG. 4  illustrates a typical cross-section of stationary closed conduit  22  at points downstream from cart  13  after pressurizing pickup shoe  24  has taken the water out of conduit  22 . 
       FIG. 5  is an enlarged view of pressurizing pickup shoe  24  with stationary closed conduit  22  in place. Sliders  26   a  and  26   b  open and close seam  25 . When pressurizing pickup shoe  24  and hence the whole linear irrigation system is moving to the left on  FIG. 5 , slider  26   a  will be opening seam  25 , and slider  26   b  will be closing seam  25 . When pressurizing pickup shoe  24  is moving to the right on  FIG. 5 , slider  26   a  will be closing seam  25 , and slider  26   b  will be opening seam  25 . Sliders  26   a  and  26   b  are attached to pressurizing pickup shoe  24  by brackets  27 . Seam is open between sliders  26   a  and  26   b , and is therefore separated into two parts,  25   a  and  25   b . Seam part  25   a  is visible and is designated on  FIG. 5 , while seam part  25   b  is on the back side of pressurizing pickup shoe  24  and invisible on  FIG. 5 . Flange  28  connects pressurizing pickup shoe  24  with vertical feed pipe  15 . 
       FIG. 6  is a perspective view of that portion of pressurizing pickup shoe  24  that would remain after a longitudinal cut along the center line and shows the inside of said pressurizing pickup shoe  24 . Because the walls of conduit  22  are too thin to be properly illustrated at the cutting plane by a pair of lines with cross hatching between them, the wall of conduit  22  is illustrated at the cutting plane by a single line with cross hatching across said single line. 
     Water enters pressurizing pickup shoe  24  through flared inlet  29 . The maximum circumference of flared inlet  29  is at location  30  and is slightly smaller than the circumference of stationary closed conduit  22  such that there will be a close fit of conduit  22  over flared inlet  29 . The shape of flared inlet  29  at location  30  conforms approximately to the cross-sectional shape of closed conduit  22  as shown in  FIG. 3 . As noted in the foregoing,  FIG. 3  is only an approximation to the shape that stationary closed conduit  22  will assume when full of water. The exact shape depends upon flow and pressure. A thin-walled plastic tube can only withstand very minimal pressure, so that the pressure in stationary closed conduit must be very low, almost nil. The lower the pressure in conduit  22 , the flatter the cross section depicted in  FIG. 3  will be. 
     The circumference of flared inlet  29  at the leading edge  31  is smaller than at location  30 , and said leading edge  31  is rounded and turned inwardly in order to prevent snagging of conduit  22  as pressurizing pickup shoe  24  moves along said conduit  22 . The trailing edge  32  of flared inlet  29  is circular and conforms to pump housing  33 . Fasteners  34  attach flared inlet  29  to pump housing  33 . If desired, a seal may be provided on the surface of inlet  29  so that there is only minimal leakage of water around the shoe. The seal may be comprised of soft pliable rubber or plastic and may be fastened to the surface of inlet  29  by means of glue or by mechanical fastener. 
     Pump  35  takes low pressure water from flared inlet  29  and discharges it at a higher pressure into diffusion chamber  36 . If pump  35  operates too slowly, the system may become flooded. If pump  35  operates too fast, it may collapse flexible conduit  22 . Therefore, pump  35  needs to be a variable speed pump governed by pressure sensors in the inlet region. 
     As shown in  FIG. 6 , pump  35  is located in the portion of the shoe  24  which is located within the conduit  22 . The pump  35  receives the low pressure water from conduit  22  and pushes pressurized water upward out of the shoe and into the sprinkler supply line. In contrast to the system described in U.S. Pat. No. 3,592,220 (Reinke), there is no pressure at the traveling opening in the stationary water conveyance system of the present invention. The rigid pressurizing pickup shoe  24  extends through the traveling opening and upstream a short distance. After the water is pressurized in the pressurizing pickup shoe, the water is completely contained within a rigid system until the water exits the sprinkler system. A seal around the leading edge of the pickup shoe upstream from the traveling opening separates the portion of the stationary water conveyance system that is carrying water from the part that is empty. The seal is only subjected to the low pressures of the stationary water in the conduit  22 . Because of the close fit between the pickup shoe and the interior surface of the conduit  22 , essentially all of the water in the conduit  22  must pass into the leading end of the pickup shoe and pump  35 . Consequently, conduit  22  is substantially void of water at all locations downstream from the pump, including the location of the traveling opening. 
     Pump  35  takes low pressure water from flared inlet  29  and discharges it at a higher pressure into diffusion chamber  36 . Pump  35  is a variable speed pump governed by pressure sensors in the inlet region. The pump may be, for example, a Goulds 6DHLC 2-stage LS Bowl pump powered by a S12972 460 V 3ph 10 HP submersible motor. A pressure transducer located within the interior of inlet  29 , and providing 1 ft. of amplitude control, sends signals to an ABB variable frequency drive  15  HP controller. The controller is located on cart  13  and will vary the frequency of the power to the pump motor  41  such that the pump  35  operates at the right speed at all times. 
     Diffusion chamber  36  has a relatively long thin slot on the top side which spreads the compact concentrated stream coming out of pump  35  into a confined stream wide in the direction longitudinal to conduit  22  and narrow in the direction lateral to conduit  22  so that this confined stream can pass through traveling opening  23  in stationary closed conduit  22  with as little disruption to the structural integrity and continuity of said conduit  22  as possible. The component of pressurizing pickup shoe  24  that extends through traveling opening  23  in said conduit  22  is called the neck or riser portion and is given designation  37  in the drawings. Neck or riser portion  37  has a non-cylindrical elongated cross-section. Water passes from neck  37  into concentrating chamber  38  through a long thin slot in concentrating chamber  38 . Concentrating chamber  38  consolidates the water flow into a compact stream and feeds said water flow into vertical pipe  15  of the linear irrigation system. 
     In addition to conveying water out of stationary closed conduit  22 , neck or riser portion  37  must also convey energy down into conduit  22  in order to operate pump  35 . Therefore, a small portion of neck  37  is divided off from the water carrying portion by wall  39 . Wall  39  extends out and forms one end of both diffusing chamber  36  and concentrating chamber  38 . Either hydraulic or electrical energy is supplied through duct  40  to motor  41 , which converts it to mechanical energy and transmits said mechanical energy to pump  35  via shaft  42 . A combination bearing and seal  43  is mounted on wall  39  and supports shaft  42 . Motor  41  is housed in motor housing  44 . Bearing  45  is mounted in the base of fairing  46  and supports shaft  42 . The function of fairing  46  is to facilitate a smooth transition of conduit  22  between being full of water and being empty, as depicted in  FIGS. 3 and 4 . When the linear irrigation system and hence the pressurizing pickup shoe are moving to the right in  FIG. 6 , fairing  46  will penetrate into the collapsed portion of conduit  22  and open up the cross section. Seam  25  will remain closed until it reaches slider  26   b . When the systems are moving to the left in  FIG. 6 , fairing  46  will help the collapsing portion of conduit  22  to lay out smoothly. Fasteners  47  attach fairing  46  to motor housing  44 . 
     Heretofore, the various components of the pressurizing pickup shoe  24  have been discussed with regard to function. Turning to manufacturing and assembly, flared inlet  29  requires a smooth and gradual transition in cross-sectional shape between the leading edge, location  30 , and the trailing edge  32  such that flared inlet  29  may be most conveniently constructed out of fiberglass over a suitable mold. The most economical and practical shape for diffusion chamber  36 , concentrating chamber  38 , pump housing  33 , and motor housing  44  are cylindrical. Pump housing  33  and diffusion chamber  36  can be one monolithic piece. Short lengths of the same tubing can be used for concentrating chamber  38  and motor housing  44 . Wall  39  is cut out and welded to the appropriate ends of diffusion chamber  36  and concentrating chamber  38 . Motor housing  44  is aligned with diffusing chamber  36  and welded to wall  39  on the assembly. Two plates are formed and welded to the assembly to make neck  37 . Pump  35  is inserted into pump housing  33  from the flared inlet  29  end of said pump housing  33 . Motor  41  is inserted into motor housing  44  from the fairing  46  end of motor housing  44 . Although shown in  FIG. 6 , sliders  26   a  and  26   b  are assembled with stationary closed conduit  22 . Standard and known techniques can be used for the remainder of the fabrication and assembly of pressurizing pickup shoe  24 . 
       FIG. 7  is a plan view of that portion of the pressurizing pickup shoe  24  that would remain after a horizontal cut through neck  37  at a location just below the point where neck  37  meets concentrating chamber  38 . Thus, as shown, neck  37  has a non-cylindrical, elongated cross-section. The forward and rearward ends of neck  37  are slightly pointed. This shape results in a minimal gap between the neck and the conduit  22  in the traveling opening, thereby reducing the possibility of dirt or other contaminants entering the reclosable fastener assembly and/or the stationary closed conduit. When seam  25  is in the open position, the two separated halves are designated  25   a  and  25   b . Seam half  25   b  was behind neck  37  and not visible in  FIG. 5 . Thus,  25   b  appears for the first time in  FIG. 7 . For purposes of clarity, shaft  42  is not shown in  FIG. 7  even though it would be visible in the cavity of neck  37 . However, the combination bearing and seal  43  that supports shaft  42  in wall  39  is shown in  FIG. 7 . 
       FIG. 8  is a perspective view of that portion of pressurizing pickup shoe  24  that would remain after a lateral cut through the forward portion of said pressurizing pickup shoe  24  at the location indicated on  FIG. 7  by line  8 - 8 . Again, because the walls of conduit  22  are too thin to be properly illustrated at the cutting plane by a pair of lines with cross-hatching between them, the wall of conduit  22  is illustrated at the cutting plane by a single line with cross-hatching across said single line. 
       FIG. 9  is similar to  FIG. 8  except that  FIG. 9  illustrates a press fit type of closure fastening device in place of the double slider arrangement illustrated in  FIG. 8 . U.S. Pat. No. 4,212,337 discloses an example of a press fit type of closure fastening device. A press fit type of closure may require that the two halves of seam  25  be held in guides when they are separated and include an apparatus for pressing the two halves together.  FIG. 9  and  FIG. 9A  illustrate the guideways. One guideway  48  would hold half seam  25   a  and another guideway  49  would hold half seam  25   b .  FIG. 9B  illustrates a tapered finger  50  that would slide into the cavity of seam  25  in order to open said seam  25  by separating half seam  25   a  from half seam  25   b .  FIG. 9B  also illustrates a pair of rollers  51  that press seam half  25   b  into seam half  25   a , thereby causing them to meld into seam  25 . Rollers  51  are supported by brackets  52   a  and  52   b . Brackets  52   a  are attached to pressurizing pickup shoe  24  on the outside of stationary closed conduit  22 , and brackets  52   b  are attached to pressurizing pickup shoe  24  at a location that is inside stationary closed conduit  22 . Another tapered finger  50 , a pair of rollers  51  and their supporting brackets  52   a  and  52   b  are also located on the opposite end of neck  37  of pressurizing pickup shoe  24  and not shown in  FIG. 9 . 
       FIG. 10  is similar to FIG. 7 of U.S. Pat. No. 4,212,337 with the numerical designations of that patent removed and with finger  50  added to the illustration. Finger  50  is tapered so that as said finger  50  moves in one direction with respect to the closure fastening device, dimension  53  will become larger and the closure fastening device will be pried open. When finger  50  moves in the opposite direction, dimension  53  will become smaller and finger  50  will disengage from the closure fastening device. 
       FIGS. 11 and 12  illustrate how a slight modification to prior art can make closure fastening devices that were developed primarily to seal household containers better suited for use in the present invention. Household containers require complete closure at both ends of the zipper profile. This can be best attained if the walls to be sealed together both enter the slider on the bottom of the slider and the two sides of the slider are interconnected across the top of the slider. This arrangement will work in the present invention but the seam that is formed will protrude outward from a line defining the circumference of the stationary closed conduit and may be subject to damage from ordinary wear and tear. 
       FIG. 11  is similar to FIG. 3 of U.S. Pat. No. 5,664,299 with the numerical designations of that patent removed and new numerical designations added.  FIG. 11  is a cross-sectional view of a slider from the &#39;299 patent near the front of the slider where the zipper profile is open. The two container walls that are about to be joined and sealed together enter the slider from the bottom. The stradling slider has an inverted U-shaped member having an integral top  54  and side walls  55  and  56 . For use in the present invention, the two container walls become walls  22   a  and  22   b  of stationary closed conduit  22 , and slider  26  is attached to bracket  27  by any suitable connection between bracket  27  and the inverted U structure of slider  26  consisting of top  54  and side walls  55  and  56 . 
       FIG. 12  illustrates a similar slider that has had part of top  54  removed and has been turned on its side so that walls  22   a  and  22   b  can enter the slider from opposite sides. Because top  54  provided structural integrity between walls  55  and  56 , an alternative means of holding walls  55  and  56  in position must be provided. One of the walls  55  and  56  is now on the inside of stationary closed conduit  22 , and the other is on the outside such that the alternative structural connection between walls  55  and  56  must pass through traveling opening  23 . Pressurizing pickup shoe  24  passes through traveling opening  23 . Thus, the modification to the slider that is illustrated in  FIG. 12  requires a pair of brackets  27   a  and  27   b  for each slider, one of which is mounted on that portion of pressurizing pickup shoe  24  that is on the outside of stationary closed conduit  22 , and the other of which is mounted on that portion of said pressurizing pickup shoe  24  which is on the inside of said stationary closed conduit  22 . 
       FIGS. 13 ,  14 ,  15  and  16  illustrate a second embodiment of the invention wherein a rigid stationary closed conduit  57  is substituted for collapsible stationary closed conduit  22 . Rigid stationary closed conduit  57  has a longitudinal slit  58  that serves the same purpose as seam  25  in collapsible stationary closed conduit  22 . Slit  58  is normally held closed and sealed by spring-like forces that can be created by pre-stressing forces in the walls of said rigid stationary closed conduit  57 , or by other means. When a linear irrigation system moves along rigid stationary closed conduit  57 , one half of a double wedge-shaped neck or riser on a specially adapted pressurizing pickup shoe pries slit  58  open to create traveling opening  23 . 
       FIG. 13  is similar to  FIG. 7  and is a plan view of that portion of a specially adapted pressurizing pickup shoe  24   a  that would remain after a horizontal cut through neck  37   a  of said pressurizing pickup shoe  24   a  at a location just below the point where neck  37   a  meets concentrating chamber  38 . Dimension  59  is the maximum width of neck  37   a . The value of dimension  59  is governed by the amount of deflection that can be imposed on rigid stationary closed conduit  57  without damage to said conduit  57 . The length of neck  37   a  is as necessary to pass the required amount of water from rigid stationary closed conduit  57  to the linear irrigation system. Pressurizing pickup shoe  24   a  is similar to pressurizing pickup shoe  24  except that neck  37   a  is shaped to conform with the traveling opening in rigid stationary closed conduit  57 , the flared inlet  29  is shaped to conform to the inside of rigid stationary closed conduit  57 , and fairing  46  is not required. Again, for purposes of clarity, shaft  42  is not shown on  FIG. 13  even though it would be visible in the cavity of neck  37   a.    
       FIGS. 14 and 15  are cross-sectional views of rigid stationary closed conduit  57  taken along lines  14 - 14  and  15 - 15 , respectively, of  FIG. 13 .  FIG. 14  illustrates a cross section at a location away from pressurizing pickup shoe  24   a  where spring forces hold slit  58  closed.  FIG. 15  is a cross section near the center of pressurizing pickup shoe  24   a  where rigid stationary closed conduit  57  has been pried open by said pressurizing pickup shoe  24   a.    
       FIG. 16  illustrates one method for pre-stressing the walls of rigid stationary closed conduit  57  in order to establish the spring-like forces that will hold slit  58  in a normally closed and sealed configuration. A circular pipe with a cross section as designated by numeral  60  in  FIG. 16  is manufactured by known methods. The diameter of pipe  60  is smaller than the desired final diameter of rigid stationary closed conduit  57  and has circumferential reinforcing near the inside edge of the wall. Next, a longitudinal slit is cut and twisting couples  61  are applied to both sides of the slit such that the cross section opens up to position  62 . Then, flanges  63  with legs  64  are attached to the edges of the slit in pipe  60 , said legs  64  becoming part of the circumference of rigid stationary closed conduit  57 . When twisting couples  61  are released, the material that originally comprised pipe  60  will attempt to return to its original configuration but will be unable to do so because legs  64  and part of flanges  63  are in the way. Pipe  60  will then assume a new position with a larger diameter and a pre-stress that will hold slit  58  normally closed and become a part of rigid stationary closed conduit  57 . 
     Reinforcing in the walls of pipe  60  can be designed to give the desired stiffness in both the longitudinal and circumferential directions by complicated but known methods of structural analysis such as curved beam analysis and orthogonally anisotropic analyses. Other techniques for obtaining pre-stressing forces are known. 
     Other variants are possible without departing from the scope of this invention.