Abstract:
A drip emitter that utilizes one or more filters and one or more labyrinths wherein the labyrinth couples the filter(s) to one or more water retainment valves that leads to at least one pool. Prevents clogging by eliminating air into the labyrinth via a water retainment valve that is situated after at least an initial portion of a labyrinth within the drip emitter. Includes non-drain, anti-siphon and ventable versions. Includes a method of two shot injection molding for embodiments of the drip emitter that include non-drain, anti-siphon and ventable variants.

Description:
[0001]    This application is a continuation in part of U.S. patent application Ser. No. 12/254,761 filed Oct. 20, 2008, the specification of which is hereby incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Embodiments of the invention described herein pertain to the field of irrigation apparatus. More particularly, but not by way of limitation, one or more embodiments of the invention enable a pressure compensated non-clogging drip emitter. 
         [0004]    2. Description of the Related Art 
         [0005]    There are multiple types of irrigation drippers. Simple drippers exist that are inserted serially along pipe, either by forcing a hole into the pipe and placing the dripper on the outside of the pipe, or by cutting the pipe and inserting the dripper in line with the pipe. These systems require great amounts of labor when providing a watering system for a large agricultural area for example. 
         [0006]    Other types of drippers include drip emitters that are inserted into pipe, generally when the pipe is extruded. This type of dripper system enables rapid deployment of great lengths of pipe, i.e., dripper line, wherein the drippers may be ordered for certain distances along the pipe for example. There are many types of emitters that may be inserted into the pipe including non-pressure compensated drippers that may provide more flow in lower areas of an agricultural drip irrigated area. 
         [0007]    Other types of emitters include pressure compensated drip emitters that provide compensated drip volumes regardless of the depth or height or pressure difference in an agricultural drip irrigated area. In addition, other features of drip emitters include “non-drain” capabilities that retain water in the pipe when the pressure in the pipe falls beneath a threshold. Non-drain drip emitters generally include a valve that does not allow for water to flow from the drip emitter until a certain pressure difference is reached with respect to internal pipe pressure versus atmospheric pressure. Such a valve may or may not include a check valve for instance. Check valves allow flow in only one direction, for example when the internal water pressure in the pipe exceeds a pressure difference with respect to atmospheric pressure. Non-drain drippers without check valves are failing after 1 year in the field and the industry is moving towards anti-siphon valve based drip emitters that inhibit backflow of air or water or mud into the pipe under negative pressure, thus inhibiting any outflow from lower elevation emitters as well as the higher elevation emitters inhibit backflow and hence prevent siphoning. Anti-siphon valves are implementations of check valves that have also heretofore been placed before the labyrinth section to keep water and air from entering the pipe. 
         [0008]    Check valves heretofore have only been placed before labyrinth sections within drip emitters. This leaves the labyrinth exposed to air and potential clogs. This pre-labyrinth check valve placement is problematic in that air can enter the labyrinth and cause a clog in the labyrinth section. When air enters the labyrinth, the water evaporates. When air mixes with water that has suspended iron, the suspended iron can solidify and cause a clog. In addition, mud can enter the labyrinth with no valve to prevent backflow into the drip emitter. 
         [0009]    The filter on cylindrical drippers fitted with non-drain or anti-siphon mechanisms before the labyrinth have traditionally been small as they must be smaller than the size of the diaphragm used to create the valve mechanism. A small filter can easily clog. Hence, not only do current non-drain and anti-siphon drip emitters clog due to problems related to material other than water entering the labyrinth, but they also clog due to the small size of the filters that have been used before the labyrinth in the flow path of water for example. 
         [0010]    Pipes fitted with non-drain elements are very difficult to evacuate as they do not allow air into the pipe through the dip emitters when under a vacuum or low pressure. When filled with water, an irrigation pipe is very heavy and is not able to be rolled up for example when certain types of crops have been harvested and the pipe is to be stored. 
         [0011]    Currently known drip emitters may clog over time for a variety of other reasons as well. Many of the reasons for clogging in currently known drip emitters are related to or a result of non-turbulent pathways, i.e., laminar transfer zones or any path of water flow that is straight enough to allow sediment to settle. For example, between the inner portion of the emitter to the pool area of the emitter, if a transfer zone is formed as a straight line, for example across a mold joint, sediment accumulates in the non-turbulent zone over time and eventually forms a clog as sediment settles. In addition, drip emitters include a filter tend to clog when the emitter is rotated so as to locate the filter downward wherein sediment settles, which clogs the filter. In addition, emitters that utilize only one hole may clog if covered by soil for a rock for example. In these situations, a second hole is not utilized to provide a level of redundancy. 
         [0012]    For at least the limitations described above there is a need for a pressure compensated non-clogging drip emitter. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    One or more embodiments of the invention enable a pressure compensated non-clogging drip emitter. Embodiments include an emitter body having an inner surface, an outer surface, a first end and a second end, a filter, a pool coupled with the outer surface wherein the pool is configured to hold water filtered by the filter when the emitter body is enclosed in a pipe, a labyrinth coupled with the outer surface wherein the labyrinth allows the water to flow from the filter to the pool through a water flow path and, a water retainment valve situated after an initial portion of the labyrinth and in the water flow path. The more of the labyrinth that is sealed to air by the water retainment valve, the more resistant to clogging the drip emitter embodiment is. For example, mud cannot flow back into the drip emitter, and air cannot creep into the labyrinth, and hence water that contains suspended iron does not form rust. Hence, the protected internal components of the drip emitter are protected from the elements, which thus prevents clogging. 
         [0014]    The emitter body may be formed as a flat object, or a cylindrical arc of less than 360 degrees, or a cylindrical arc of a full 360 degrees or any other shape that may fit inside a pipe for example. 
         [0015]    The water retainment valve may be constructed in a manner or otherwise configured to either allow no backflow of air or water, or allow the backflow of air or water into the drip emitter when a pressure internal to the drip emitter is below a threshold pressure. For example, the water retainment valve may be configured with flaps. Depending on the configuration of the flaps, the valve may be non-drainable, or conversely, ventable in that under low pressures or a vacuum or negative pressure, the flaps may for example change direction to allow airflow into the drip emitter and pipe. In ventable embodiments, the flaps may be configured to point under no pressure in a direction of normal water flow under positive pressure with respect to internal pipe pressure and external air pressure. For non-drain embodiments, when the pressure is below a threshold then the water retainment valve ceases to allow water to flow. Ventable embodiments allow for the enclosing pipe to be rolled up for example while non-drain embodiments do not allow air into the pipe and hence do not allow for easily rolling up the pipe. Anti-siphon embodiments may be implemented similar to ventable embodiments, with longer flaps that are unable to bend back in towards the labyrinth for example. 
         [0016]    Embodiments of the invention may be configured with a pressure compensating chamber that is adapted to allow pressure from the water in the emitter to limit a compressible element that in effect controls the output pressure and/or flow of water from the emitter. In one or more embodiments of the invention, the pressure compensation chamber is formed together with the water retainment valve in an integrated unit although this is not required. 
         [0017]    An embodiment of the method of producing the drip emitter includes selecting a first material for injection molding for an emitter body, selecting a second material for injection molding wherein said second material comprises an elastomeric material to effect regulation of the drip emitter, injecting an injection mold with a said first material and said second material in separate shots in a single mold to form the drip emitter, and, cross-linking said second material to increase elasticity of said second material after injection but before inserting said drip emitter into a pipe. The method may also include forming a water retainment valve with said second material in the single mold, forming a ventable water retainment valve with said second material in the single mold, forming a mechanical engagement between said first material and said second material, forming a mechanical engagement between said first material and said second material wherein said mechanical engagement comprises at least one interlocking element formed into said first material and corresponding at least one interlocking element formed into said second material. In addition, the method for producing the drip emitter may include forming a water retainment valve that is configured to hinder or allow no backflow of air or water into the drip emitter when a pressure internal to the drip emitter is below the pressure external to the pipe. 
         [0018]    Embodiments of the invention may be manufactured in a novel manner by injecting both the emitter and pressure compensating diaphragm and/or non-drain valve within an injection mold, for example using multiple shots of different material into the mold. In one or more embodiments, a pliable material is utilized for the pressure compensating component and/or ventable valve while a less pliable material for example a material that does not flex as much is utilized for the emitter body. 
         [0019]    In one or more embodiments, after injection molding but before insertion into the pipe, cross-linking may be performed to enable the elastomer to retain shape and elasticity characteristics over time. This may be done using UV light, hot water, steam, beta radiation or any other technology that allows the materials to cross-link. Typically, cross-linked materials do not bond with polyethylene, so during injection cross-linking is undesirable since the elastomer will have to bond with PE. 
         [0020]    One or more embodiments of the invention may be configured to restrict water flow, wherein the water retainment valve is alternately opened and closed under normal operation for example due to the Bernoulli effect to provide restricted water flow. Embodiments of the invention may be utilized in restricting or alternately open/close configurations for low flow level implementations. If for example the instantaneous flow from a dripper is 4 liters per hour with a pressure that is changing from 0 to 15 psi intermittently then the average flow might be 0.5 liters per hour or lower. This allows for use of 1) longer laterals of pipe because the drippers are not all flowing at the same time so there is less pressure loss in the pipe, 2) larger labyrinths for low flows (larger labyrinths clog less), 3) reduction in pumping costs and 4) extremely low flows become possible. For example, in embodiments that employ a water retainment valve after the labyrinth, this restricting effect occurs since the water pressure at the water retainment valve is the pressure after the labyrinth and compensation chamber and is much lower than pipe pressure and closer to atmospheric pressure (pressure outside the pipe). Hence, if the water pressure at the water retainment valve is close to the threshold pressure the flaps crack open and allow flow through the valve, however the Bernoulli principle states that as velocity of the water increases, when the flow increases from stagnate velocity V=0 to flow V&gt;0, the pressure decreases. When the pressure has decreased below the threshold pressure the flaps close until the water is stagnant and the pressure quickly builds towards pipe pressure and exceeds the threshold, therein opening the water retainment valve. This cycle keeps repeating within a pressure range. 
         [0021]    In non-drain drip emitters there are two threshold pressures of importance. As water fills an empty pipe and the pressure raises the drip emitters allow water to flow at the opening pressure threshold. When the pump that pressurizes water in the pipe is turned off, the drip emitters continue to allow water to flow until the closing pressure threshold is met and the water ceases flowing. It is desirable to have the closing pressure be high, however in non-drain drippers that exist today the closing pressure is lower than the opening pressure. With embodiments of the invention that make use of flaps, and under restricted pressure ranges, the water retainment valve is continuously alternating between a closed and open state during normal operation and the closing pressure is higher and closer or equal to the opening pressure. 
         [0022]    Embodiments of the invention or method of producing embodiments of the invention may optionally utilize an inwardly projecting filter prevent clogging when the emitter oriented rotationally downward in the field as the filter is not a potential well and hence sediment does not drop into it. In addition, inwardly projecting filter embodiments provide a snorkel effect that enables faster moving and cleaner water to enter the emitter via the filter, hence eliminating the potential to clog in a second manner. Thus inwardly projecting filter embodiments eliminate clogs in two ways, by avoiding sediment with a height offset and avoiding sediment by selecting faster moving water away from the pipe outer surface. An emitter may also utilize more than one filter in a redundant configuration to either supply both pools on each side of the emitter or alternatively to supply an associated pool in a one-to-one manner. 
         [0023]    Embodiments of the invention may further include a pool coupled with the outer cylindrical surface wherein the pool is configured to hold water filtered by the filter or inwardly offset filter when the hollow cylindrical emitter body is enclosed in a pipe. Embodiments further include a labyrinth coupled with the outer cylindrical surface wherein the labyrinth may optionally maximize use of turbulent transfer zones, at least after water enters the labyrinth, and wherein the labyrinth allows the water to flow from the filter or filter to the pool. Through the use of turbulent transfer zones once the water enters the labyrinth, sediment is continuously forced through the labyrinth and has no location to settle and hence the labyrinth minimizes the potential to clog. In other words, laminar flow transfer zones are avoided as these type of “straight” paths tend to clog over time with sediments. By utilizing a filter or an inwardly offset filter and a labyrinth that avoids laminar flow zones, embodiments of the invention so configured minimize the potential to clog in multiple ways. 
         [0024]    Once an embodiment of the emitter is enclosed in a pipe, the pool is thus sealed, for example via a wall at one end of the emitter and a side of the labyrinth, for example when the labyrinth extends outwardly from the outer cylindrical surface of the emitter. The pool is tapped via one or more hole(s) in the enclosing pipe to allow for the water running in the inner portion of the pipe and inner portion of the emitter to flow through the filter and labyrinth to the pool and out the hole at a rate that is controlled by the particular shape and size of the labyrinth for example. 
         [0025]    In one or more embodiment of the invention, a symmetrical embodiment may be utilized that provides two pools, two labyrinths and optionally two pressure compensation and/or two water retainment valves. This embodiment provides a robust redundant embodiment that continues to work even if one labyrinth were to clog, or if one hole into the pipe associated with a particular emitter were to be externally plugged, buried or blocked. Several embodiments of redundant configurations may be formed that include a two pool embodiment with one or more labyrinths, i.e., one labyrinth with a “T” or fork section, or two labyrinths, each flowing to a separate pool. Alternatively, the embodiment can be doubled to form more than one filter or inwardly offset filter, for example offset rotationally by 180 degrees, with separate labyrinth(s) and pool(s) coupled therewith for even more redundancy. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    The above and other aspects, features and advantages of the invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
           [0027]      FIG. 1  is a perspective view of an embodiment of the drip emitter. 
           [0028]      FIG. 2  is a perspective view of an embodiment of the drip emitter shown as situated inside a pipe or hose. 
           [0029]      FIG. 3  is a bottom view of an embodiment of the drip emitter. 
           [0030]      FIG. 4  is a side view of an embodiment of the drip emitter. 
           [0031]      FIG. 5  is a top view of an embodiment of the drip emitter. 
           [0032]      FIG. 6  is a secondary side view of an embodiment of the drip emitter. 
           [0033]      FIG. 7  is a cross-section end view of an embodiment of the drip emitter shown in  FIG. 6 . 
           [0034]      FIG. 8  is an end view of an embodiment of the drip emitter. 
           [0035]      FIG. 9  is a cross-section side view of an embodiment of the drip emitter shown in  FIG. 8 . 
           [0036]      FIG. 10  is a top view of an embodiment of the drip emitter. 
           [0037]      FIG. 11  is a cross-section side view of an embodiment of the drip emitter shown in  FIG. 10 . 
           [0038]      FIG. 12  is perspective view of an embodiment of the water retainment valve. 
           [0039]      FIG. 13  is a top view of an embodiment of the water retainment valve. 
           [0040]      FIG. 14  is a cross-section view of an embodiment of the water retainment valve shown in  FIG. 13 . 
           [0041]      FIG. 15  is a perspective view of a second embodiment of the drip emitter. 
           [0042]      FIG. 16  is a top view of a second embodiment of the drip emitter. 
           [0043]      FIG. 17  is a side cross-section view of a second embodiment of the drip emitter shown in  FIG. 16 . 
           [0044]      FIG. 18  is an end cross-section view of a second embodiment of the drip emitter shown in  FIG. 16 . 
           [0045]      FIG. 19  is a side view of a second embodiment of the drip emitter. 
           [0046]      FIG. 20  is an end view of a second embodiment of the drip emitter. 
           [0047]      FIG. 21  is a bottom view of a second embodiment of the drip emitter. 
           [0048]      FIG. 22  is a perspective bottom view of a second embodiment of the drip emitter. 
           [0049]      FIG. 23  is a perspective view of a second embodiment of the water retainment valve. 
           [0050]      FIG. 24  is a top view of a second embodiment of the water retainment valve. 
           [0051]      FIG. 25  is an end cross-section view of a second embodiment of the water retainment valve shown in  FIG. 24 . 
           [0052]      FIG. 26  is end view of a second embodiment of the water retainment valve. 
           [0053]      FIG. 27  is a side cross-section view of a second embodiment of the water retainment valve shown in  FIG. 26 . 
           [0054]      FIG. 28  is a bottom view of a second embodiment of the water retainment valve. 
           [0055]      FIG. 29  is a graph of flow versus pressure in a non-drain embodiment of the water retainment valve. 
           [0056]      FIG. 30  is a graph of flow versus pressure in a non-drain embodiment of the water retainment valve with flaps that are not fully closed at zero pressure difference. 
           [0057]      FIG. 31  is a graph of flow versus pressure in ventable and anti-siphon embodiments of the water retainment valve. 
           [0058]      FIG. 32  is a graph of flow versus pressure in ventable and anti-siphon embodiments of the water retainment valve with flaps that are not fully closed at zero pressure difference. 
           [0059]      FIG. 33  shows a view of the pressure compensation and ventable valve components at a given pressure range depicted at flow D in  FIGS. 29 and 30 . 
           [0060]      FIG. 34  shows a view of the pressure compensation and ventable valve components at a given pressure range depicted at flow C in  FIGS. 29 and 30 . 
           [0061]      FIG. 35  shows a view of the pressure compensation and ventable valve components at a given pressure range depicted at flow B in  FIGS. 29 and 30 . 
           [0062]      FIG. 36  shows a view of the pressure compensation and ventable valve components at a given pressure range depicted at flow A in  FIGS. 29 and 30 . 
           [0063]      FIG. 37  shows a view of the pressure compensation and ventable valve components at a given pressure range depicted at flow D in  FIGS. 31 and 32 . 
           [0064]      FIG. 38  shows a view of the pressure compensation and ventable valve components at a given pressure range depicted at flow C in  FIGS. 31 and 32 . 
           [0065]      FIG. 39  shows a view of the pressure compensation and ventable valve components at a given pressure range depicted at flow B in  FIGS. 31 and 32 . 
           [0066]      FIG. 40  shows a view of the pressure compensation and ventable valve components at a given pressure range depicted at flow A in  FIGS. 31 and 32 . 
           [0067]      FIG. 41  shows a side cross-section view of the pressure compensation and ventable valve components at a given pressure range depicted at flow D in  FIGS. 29 and 30 . 
           [0068]      FIG. 42  shows a side cross-section view of the pressure compensation and ventable valve components at a given pressure range depicted at flow B in  FIGS. 29 and 30 . 
           [0069]      FIG. 43  shows a side cross-section view of the pressure compensation and ventable valve components at a given pressure range depicted at flow A in  FIGS. 29 and 30 . 
           [0070]      FIG. 44  shows a perspective end view of a non-drain valve showing flaps pointing inward under no pressure. 
           [0071]      FIG. 45  shows a perspective end view of a non-drain valve showing flaps pointing outward under no pressure. 
           [0072]      FIG. 46  shows a side cross-section view of an injection mold for manufacture of an embodiment of the invention. 
           [0073]      FIG. 47  shows an opposing side cross-section view with respect to  FIG. 40  of an injection mold for manufacture of an embodiment of the invention. 
           [0074]      FIG. 48  shows an end cross-section view of an injection mold for manufacture of an embodiment of the invention. 
           [0075]      FIG. 49  shows an end cross-section view of an injection mold for manufacture of an embodiment of the invention showing an insert for creation of an embodiment of the pressure compensated ventable valve. 
           [0076]      FIG. 50  shows a perspective side view of an embodiment that enables mechanical engagement of the water retention valve with the drip emitter with area that holds the water retention valve visible. 
           [0077]      FIG. 51  shows a perspective view from a different angle with respect to  FIG. 50 . 
           [0078]      FIG. 52  shows a side view of an embodiment that enables mechanical engagement of the water retention valve with the drip emitter wherein the water retention valve is mechanically engaged to the drip emitter. 
           [0079]      FIG. 53  shows an end view of the drip emitter with a mechanically engaged ventable embodiment of the water retention valve. 
           [0080]      FIG. 54  shows a side view of the drip emitter with a mechanically engaged ventable embodiment of the water retention valve. 
           [0081]      FIG. 55  shows a top view of the drip emitter with a mechanically engaged ventable embodiment of the water retention valve. 
           [0082]      FIG. 56  shows a side cross-section view of the drip emitter along the section line of  FIG. 55 , with a mechanically engaged ventable embodiment of the water retention valve. 
           [0083]      FIG. 57  shows an empty area that is configured as the water retainment valve slot. 
           [0084]      FIG. 58  shows a top view of  FIG. 55  without the mechanically engaged water retention valve. 
           [0085]      FIG. 59  shows a side view of the drip emitter showing the water retainment valve slot without a mechanically engaged water retention valve inserted. 
           [0086]      FIG. 60  shows a perspective view of an embodiment of mechanically engaged water retention valve having flaps. 
           [0087]      FIG. 61  shows a side view of the mechanically engaged water retention valve of  FIG. 60 . 
           [0088]      FIG. 62  shows a cross-section view of the mechanically engaged water retention valve of  FIG. 61 . 
           [0089]      FIG. 63  shows an opposing side view of the mechanically engaged water retention valve of  FIG. 61  showing flaps. 
           [0090]      FIG. 64  shows a bottom view of the mechanically engaged water retention valve showing teeth for mechanical engagement to the drip emitter via water retainment valve slot as shown in  FIG. 59 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0091]    A pressure compensated non-clogging drip emitter will now be described. In the following exemplary description numerous specific details are set forth in order to provide a more thorough understanding of embodiments of the invention. It will be apparent, however, to an artisan of ordinary skill that the present invention may be practiced without incorporating all aspects of the specific details described herein. In other instances, specific features, quantities, or measurements well known to those of ordinary skill in the art have not been described in detail so as not to obscure the invention. Readers should note that although examples of the invention are set forth herein, the claims, and the full scope of any equivalents, are what define the metes and bounds of the invention. 
         [0092]      FIG. 1  is a perspective view of an embodiment of drip emitter  100 . Embodiments include an emitter body having inner surface  101 , outer surface  102  that forms the floor of the emitter working elements, first end  110  and second end  111 . The emitter of  FIG. 1  is inserted into a pipe or hose as is shown as a shaded tube in  FIG. 2  wherein holes are created in the hose to allow water flowing from the inside of the pipe, and hence inside of inner surface  101  through filter  120 , (into labyrinth entry  301 , through labyrinth  140 , through labyrinth transfer zone location  141 , to labyrinth exit  142 , to channel  310 , to water retainment valve  281  for example as per  FIGS. 3-6 ) and into pools  130  and  130   a  and out of holes  202  and  202   a  respectively (see  FIG. 2 ). Embodiments provide pool  130  formed at the deepest offset by outer cylindrical surface  102 , wherein pool  130  is configured to hold water filtered by filter  120 . Water retainment valve  281  protects labyrinth  140  from the elements by preventing the backflow of air or water or mud for example into the drip emitter. Ventable embodiments of water retainment valve  281  allow for draining water from, and rolling of an enclosing pipe by lowering the internal pressure within the enclosing pipe (as per  FIG. 2 ) to a pressure below a backflow threshold pressure. This allows air to enter water retainment valve  281  which enters the labyrinth and hence enters the pipe through the reverse path of normal water flow. 
         [0093]    Embodiments further include labyrinth  140  coupled with the outer cylindrical surface wherein labyrinth  140  may utilize turbulent transfer zones once water enters the labyrinth and wherein labyrinth  140  allows the water to flow from inwardly offset filter  120  to pool  130 . As shown in  FIGS. 1-3 , labyrinth  140  includes teeth that point inwardly into the path of water flow, wherein the teeth disrupt the flow of water through labyrinth  140  and provide turbulent transfer zones throughout labyrinth  140 . Any shape may be utilized to create turbulent transfer zones, including but not limited to teeth, or any other geometric shape such as square waves, saw tooth shapes, or any other shape that provides for non-linear or non-laminar water flow. 
         [0094]    Once an embodiment of the emitter is enclosed in a pipe, pool  130  is thus sealed, for example via the wall at first end  110  of the emitter and side  112  of the labyrinth/filter section. The “depth” of the pool  130  may be any depth that allows for the desired amount of water to flow through the particular embodiment. For example, when labyrinth  140  extends outwardly from the outer cylindrical surface of the emitter by a desired distance, this distance sets the depth of the path of the water through the labyrinth. By configuring the labyrinth with the desired number of turbulent features, for example teeth and setting the width of the water path through the labyrinth, any water flow amount can be easily configured for the desired product implementation. Pool  130  is tapped via hole  202  in the enclosing pipe to allow for the water running in the inner portion of the pipe and inner portion of the emitter to flow through inwardly offset filter  120  and labyrinth  140  to pool  130  and out hole  202 . In other words, the rate of water flow is controlled by the particular shape and size of the labyrinth for example the length, cross-sectional area, number of teeth, length of teeth of the turbulent zones. Grid  170  is formed to minimize the amount of plastic for example utilized in each emitter, and provides a higher coefficient of static friction between the enclosing pipe and is optional in that it does not form a part of the water flow mechanism of embodiments of the invention. 
         [0095]    One or more embodiments of the invention provide an elongated filter as shown in  FIGS. 1-3 , that is aligned lengthwise along the axis of the cylinder forming the emitter, for example lengthwise parallel along the axis of the cylinder of the emitter. The filter inward offset can be any depth greater than or equal to 0 mm from the inner diameter of the drip emitter inner surface  101  and the ends of the filter may be angled to provide for a more streamlined flow of water past the filter for example to aid in the snorkel effect of taking in faster moving water for embodiments having a filter inward offset greater than 0 mm. In one or more embodiment of the invention, a symmetrical embodiment may be utilized that provides two pools, i.e.,  130 ,  130   a  as well as two labyrinths and/or two water retainment valves. This embodiment or any embodiments having more than two labyrinths and/or water retainment valves is in keeping with the spirit of the invention and is not shown for brevity. An embodiment of a robust implementation is shown in the parent application to this application which has been incorporated by reference above. Use of multiple redundant components within a single drip emitter provides a robust redundant embodiment that continues to work even if one labyrinth were to clog, or if one hole into the pipe associated with a particular emitter were to be externally plugged, buried or blocked. The labyrinth may be coupled with the emitter by forming the emitter via injection molding so that the labyrinth extends outwardly from the outer cylindrical surface of the emitter. In this embodiment, water is sealed on the bottom by the outer cylindrical surface of the emitter, i.e., the floor of the labyrinth, and is further sealed by the outwardly extending walls of the turbulent zones for example. In addition, water is sealed by the inner surface of the enclosing pipe into which the emitter is placed. The exit from the labyrinth allows water to flow into the pool. 
         [0096]      FIG. 2  is a perspective view of an embodiment of the shown in enclosing pipe  201  that is shown with holes  202  and  202   a  to provide exits for drip water. Pipe  201  is shown as a shaded cylindrical cut-away tube and may be formed of any material including but not limited to plastic. Embodiments of the invention may be inserted into pipe  201  using an extrusion process for example. The emitters may be inserted at fixed timing or fixed distance or any other displacement offset depending on the intended use for the implementation. For example, for a drip emitter system to be utilized for trees, the emitters may be introduced into pipe  201  at large intervals with respect to a drip emitter system for a garden having smaller plants. 
         [0097]      FIG. 3  is a bottom view of an embodiment of the drip emitter. As shown, water flows out of the page toward the reader from filter  120  through labyrinth entry  301  and into labyrinth  140 . The labyrinth may utilize turbulent transfer zones as the water for example travels toward the right in the labyrinth section closest to inwardly offset filter  120 , bends at transfer zone location  141  and travels to labyrinth exit  142  into pool  130 . From pool  130  water drips from the pipe at hole  202  (see  FIG. 2 ). 
         [0098]      FIG. 4  is a side view of an embodiment of the drip emitter. In this view, water retainment valve  281  is shown from the end, wherein the flaps  401  are visible, wherein the flaps may be configured for non-drain or ventable operation based on their shape and orientation. Water retainment valve  281  may also be configured with an integrated pressure compensation valve. 
         [0099]      FIG. 5  is a top view of an embodiment of the drip emitter. In this view, water retainment valve  281  is seen from the top wherein the water flow path under normal drip emitter irrigation allows water to flow out of the water retainment valve to pool entries  502  and  502   a  from water retainment valve exit location  501 . 
         [0100]      FIG. 6  is a secondary side view of an embodiment of the drip emitter, i.e., opposite side of  FIG. 4 .  FIG. 7  is a cross-section end view of an embodiment of the drip emitter shown in  FIG. 6 . In this view, cross section of water retainment valve  281  is shown with side view of flaps  401 . 
         [0101]      FIG. 8  is an end view of an embodiment of the drip emitter.  FIG. 9  is a cross-section side view of an embodiment of the drip emitter shown in  FIG. 8 . In this view, side cross section of water retainment valve  281  is shown with end view of flaps  401 . 
         [0102]      FIG. 10  is a top view of an embodiment of the drip emitter.  FIG. 11  is a cross-section side view of an embodiment of the drip emitter shown in  FIG. 10 . In this view, water retainment valve slot  200  is shown where water retainment valve  281  is placed before enclosing the drip emitter in an enclosing pipe. 
         [0103]      FIG. 12  is a perspective view of an embodiment of water retainment valve  281 , which in this embodiment is a pressure compensated ventable water retainment valve that may be configured as a ventable or non-drain water retainment valve. 
         [0104]      FIG. 13  is a top view of an embodiment of the water retainment valve.  FIG. 14  is a cross-section view of an embodiment of the water retainment valve shown in  FIG. 13  showing an end view of flaps  401 . 
         [0105]      FIG. 15  is a perspective view of a second embodiment of the drip emitter. In this semi-cylindrical embodiment, water enters the drip emitter through filter  120 , passes into labyrinth  140 , through water retainment valve  281  that may also include an integrated pressure compensation member and into pool  130 . Placement of the water retainment valve after the initial portion of the labyrinth, or after the end of the labyrinth allows for minimizing the labyrinth to exposure to the elements and prevents clogging. 
         [0106]      FIG. 16  is a top view of a second embodiment of the drip emitter. In this view, water retainment valve  281  is shown from the top.  FIG. 17  is a side cross-section view of a second embodiment of the drip emitter shown in  FIG. 16 . In this view flaps  401  are shown from the side.  FIG. 18  is an end cross-section view of a second embodiment of the drip emitter shown in FIG.  16 . In this view, flaps  401  are seen from the end within water retainment valve  281 . 
         [0107]      FIG. 19  is a side view of a second embodiment of the drip emitter. In this view, flaps  401  are seen from the end within water retainment valve  281 . 
         [0108]      FIG. 20  is end view of a second embodiment of the drip emitter. In this particular embodiment the height of the drip emitter is 3.3 mm. Any depth of drip emitter may be manufactured depending on the implementation requirements. 
         [0109]      FIG. 21  is a bottom view of a second embodiment of the drip emitter. In this view, the drip emitter is shown as 29.8 mm in length and 8.4 mm in width. Any length or width of drip emitter can be manufactured depending on the implementation requirements.  FIG. 22  is a perspective bottom view of a second embodiment of the drip emitter. 
         [0110]      FIG. 23  is a perspective view of a second embodiment of the water retainment valve.  FIG. 24  is a top view of a second embodiment of the water retainment valve.  FIG. 25  is an end cross-section view of a second embodiment of the water retainment valve shown in  FIG. 24 . In this embodiment, flaps  401  in water retainment valve  281  are shown from the end.  FIG. 26  is end view of a second embodiment of the water retainment valve.  FIG. 27  is a side cross-section view of a second embodiment of the water retainment valve shown in  FIG. 26 . In this embodiment, flaps  401   a  point inward under no pressure and form a non-drain embodiment of the water retention valve.  FIG. 28  is a bottom view of a second embodiment of the water retainment valve. 
         [0111]      FIG. 29  is a graph of flow versus pressure in a non-drain embodiment of the water retainment valve. In  FIG. 29 , the water retention valve is constructed with inwardly pointing flaps (against the flow of water in the water path) that touch one another under zero pressure difference. As shown in flow area A, under negative pressure, air can backflow into the drip emitter as the flaps point inward and are easily opened under negative pressure. As shown in flow area B, at a pressure slightly below atmospheric pressure within the drip emitter up until a particular threshold, for example 0.5 atmosphere higher than atmospheric pressure, there it no water flow out of the drip emitter as the inwardly pointing flaps are pressed against one another under the pressure. As shown in flow area C, at above 0.5 atmosphere pressure difference between internal drip emitter and atmospheric pressure, the flaps are forced in the opposite direction along the water flow path and begin to open. As shown in flow area D, once the flaps have fully opened, the water flow rate is limited by the resistance to water flow within the drip emitter water flow path. 
         [0112]    In  FIG. 30 , the water retention valve is constructed with inwardly pointing flaps (against the flow of water in the water path) that do not touch one another under zero pressure difference. For example, there is a slight gap between the flaps under no pressure difference between internal and external drip emitter pressure. As shown in flow area A, under negative pressure, air can backflow into the drip emitter as the flaps point inward and are easily opened under negative pressure. As shown in flow area E, water slightly flows through the flaps until the flaps have enough pressure against them, which requires a slight flow of water to press the flaps together. As shown in flow area B, at a pressure slightly above atmospheric pressure within the drip emitter up until a particular threshold, for example 0.5 atmosphere higher than atmospheric pressure, there it no water flow out of the drip emitter as the inwardly pointing flaps are pressed against one another under the pressure. As shown in flow area C, at above 0.5 atmosphere pressure difference between internal drip emitter and atmospheric pressure, the flaps are forced in the opposite direction along the water flow path and begin to open. As shown in flow area D, once the flaps have fully opened, the water flow rate is limited by the resistance to water flow within the drip emitter water flow path. 
         [0113]      FIG. 31  is a graph of flow versus pressure in ventable and anti-siphon embodiments of the water retainment valve. In  FIG. 31 , the water retention valve is constructed with outwardly pointing flaps (aligned in the direction of the flow of water in the water path when irrigating) that touch one another under zero pressure difference. As shown in flow area A, under negative pressure, air can backflow into the drip emitter as the flaps change direction to point inward and are thus opened under negative pressure. As shown in flow area B, at a negative pressure below atmospheric pressure within the drip emitter up until a particular threshold, for example 0.1 atmosphere higher than atmospheric pressure, there it no water flow out of the drip emitter as the outwardly pointing flaps are pressed against one another. As shown in flow area C, at above for example 0.1 atmosphere pressure difference between internal drip emitter and atmospheric pressure, the flaps are pointed in the direction along the water flow path and begin to open. As shown in flow area D, once the flaps have fully opened, the water flow rate is limited by the resistance to water flow within the drip emitter water flow path. 
         [0114]      FIG. 32  is a graph of flow versus pressure in ventable and anti-siphon embodiments of the water retainment valve with flaps that are not fully closed at zero pressure difference. In  FIG. 32 , the water retention valve is constructed with outwardly pointing flaps (in the direction of the flow of water in the water path during irrigation) that do not touch one another under zero pressure difference. For example, there is a slight gap between the flaps under no pressure difference between internal and external drip emitter pressure. As shown in flow area A, under negative pressure, air can backflow into the drip emitter as the flaps change direction to point inward and are thus opened under negative pressure. As shown in flow area B, at a negative pressure below atmospheric pressure within the drip emitter up until a particular threshold, for example −0.1 atmosphere lower than atmospheric pressure, there it no water flow out of the drip emitter as the outwardly pointing flaps are pressed against one another. As shown in flow area E, air slightly flows through the flaps into the drip emitter until the flaps have enough pressure against them, which requires a slight flow of inward flow of air (or any other matter) to press the flaps together. As shown in flow area C, at above for example 0.0 atmosphere pressure difference between internal drip emitter and atmospheric pressure, the flaps are pointed in the direction along the water flow path and are already slightly open at zero pressure difference. The flaps begin to open more as the pressure difference increases. As shown in flow area D, once the flaps have fully opened, the water flow rate is limited by the resistance to water flow within the drip emitter water flow path. 
         [0115]      FIG. 33  shows a view of the pressure compensation and ventable valve components at a given pressure range depicted at flow D in  FIGS. 29 and 30 . In this view, under positive relative pressure as shown at pressure chart  3104 , pressure compensation element  3101  bends toward water flow path  3102  which tends to limit the flow of water through water flow path  3102  as the pressure rises. Under normal positive water flow through water flow path  3102 , flaps  3103  that form a water retainment valve are open and water flow exits drip emitter  100  to water an agricultural area for example. 
         [0116]      FIG. 34  shows a view of the pressure compensation and ventable valve components at a given pressure range depicted at flow C in  FIGS. 29 and 30 . In this view, under a positive threshold pressure, positive water flow occurs through drip emitter  100 . Pressure compensation element  3101  is not active to the point of limiting the flow out of the drip emitter as the pressure is low enough so that pressure compensation element  3101  does not bend into water flow path  3102 . Flaps  3103  are slightly open under this input pressure and a slight flow of water exits the drip emitter. 
         [0117]      FIG. 35  shows a view of the pressure compensation and ventable valve components at a given pressure range depicted at flow B in  FIGS. 29 and 30 . In this view, under a small and/or negative pressure, flaps  3103  change direction to point into the drip emitter. Although no flow of air enters the drip emitter, a small increase in negative pressure results in the state shown in  FIG. 36 . 
         [0118]      FIG. 36  shows a view of the pressure compensation and ventable valve components at a given pressure range depicted at flow A in  FIGS. 29 and 30 . In this view, which corresponds to a ventable embodiment which allow for pipe draining and rolling for example, flaps  3103  open as a large enough backflow pressure threshold is applied to the pipe with respect to atmospheric pressure external to the pipe. As flaps  3103  open, air  3401  (or water), enters water flow path  3102 , labyrinth  140 , filter  120  and pipe  201 . 
         [0119]      FIG. 37  shows a view of the pressure compensation and ventable valve components at a given pressure range depicted at flow D in  FIGS. 31 and 32 . In this view, under positive relative pressure as shown at pressure chart  3104 , pressure compensation element  3101  bends toward water flow path  3102  which tends to limit the flow of water through water flow path  3102  as the pressure rises. Under normal positive water flow through water flow path  3102 , flaps  3103  that form a water retainment valve are open and water flow exits drip emitter  100  to water an agricultural area for example. 
         [0120]      FIG. 38  shows a view of the pressure compensation and ventable valve components at a given pressure range depicted at flow C in  FIGS. 31 and 32 . In this view, under a positive threshold pressure, positive water flow occurs through drip emitter  100 . Pressure compensation element  3101  is not active to the point of limiting the flow out of the drip emitter as the pressure is low enough so that pressure compensation element  3101  does not bend into water flow path  3102 . Flaps  3103  are slightly open under this input pressure and a slight flow of water exits the drip emitter. 
         [0121]      FIG. 39  shows a view of the pressure compensation and ventable valve components at a given pressure range depicted at flow B in  FIGS. 31 and 32 . In this view, under a small and/or negative pressure, flaps  3103  change direction to point into the drip emitter. Although no flow of air enters the drip emitter, a small increase in negative pressure results in the state shown in  FIG. 40 . 
         [0122]      FIG. 40  shows a view of the pressure compensation and ventable valve components at a given pressure range depicted at flow A in  FIGS. 31 and 32 . In this view, which corresponds to a ventable embodiment which allow for pipe draining and rolling for example, flaps  3103  open as a large enough backflow pressure threshold is applied to the pipe with respect to atmospheric pressure external to the pipe. As flaps  3103  open, air  3401  (or water), enters water flow path  3102 , labyrinth  140 , filter  120  and pipe  201 . 
         [0123]      FIG. 41  shows a side cross-section view of the pressure compensation and ventable valve components at a given pressure range depicted at flow D in  FIGS. 29-32 . This corresponds to the pressure range shown in  FIG. 34  (also see  FIG. 38 ) with slight positive water flow from the drip emitter. 
         [0124]      FIG. 42  shows a side cross-section view of the pressure compensation and ventable valve components at a given pressure range depicted at flow B in  FIGS. 29-32 . This corresponds to the pressure range shown in  FIG. 35  for a ventable embodiment at the point of allowing air to enter the drip emitter. 
         [0125]      FIG. 43  shows a side cross-section view of the pressure compensation and ventable valve components at a given pressure range depicted at flow A in  FIGS. 29-32 . This corresponds to the pressure range shown in  FIG. 36  for a ventable embodiment with air entering the drip emitter. 
         [0126]      FIG. 44  shows a perspective end view of an anti-siphon water retainment valve embodiment  3801  showing flaps  3802  pointing outwardly (to the left in the figure) under no pressure. This embodiment allows for no entry of air under negative pressure if the flaps are long, if the flaps are short, then the valve can be vented. (See flow area A of  FIG. 3   1 ). By constructing the flaps slightly shorter, the flaps are able to flip direction, which creates a ventable embodiment of the water retention valve that allows for rolling up the enclosing pipe for example by allowing air to enter the water retention valve when for example a low pressure is applied to the water in the enclosing pipe. (See flow area A of  FIGS. 32 ). 
         [0127]      FIG. 45  shows a perspective end view of a non-drain water retainment valve embodiment  3901  showing flaps  3902  pointing inwardly (to the right in the figure) under no pressure. Depending on the construction of the flaps, i.e., whether slightly touching or not under zero pressure difference between internal drip emitter pressure and external atmospheric pressure, (see flow areas in  FIGS. 29A-B ). 
         [0128]      FIG. 46  shows a side cross-section view of an injection mold for manufacture of an embodiment of the invention. In this view, drip emitter content  4003  is shown as injected into injection mold with bottom  4004 , elements  4002  and  4002   a  and injection mold top  4001  that form the remainder of mold for the exterior of drip emitter content  4003 . Water retainment valve place holder  4000  creates a void in which a water retainment valve may be formed using the same injection mold with a second injection. 
         [0129]      FIG. 47  shows an opposing side cross-section view with respect to  FIG. 46  of an injection mold for manufacture of an embodiment of the invention. In this view, water retainment valve injection mold top  4101  replaces water retainment valve place holder  4000  for the second injection. As shown, water retainment valve content  4102  is injected into the mold wherein the material may be elastomeric for example. Block  4103  prohibits water retainment valve content  4102  from an internal portion of the water retainment valve. 
         [0130]      FIG. 48  shows an end cross-section view of an injection mold for manufacture of an embodiment of the invention. In this embodiment, water retainment valve place holder  4000  is in place for the first injection of drip emitter content  4003 . 
         [0131]      FIG. 49  shows an end cross-section view of an injection mold for manufacture of an embodiment of the invention showing an insert for creation of an embodiment of the pressure compensated ventable valve. In this view, block  4103   a  and  4103   b  are shown in cross section which create a void which is the internal portion of pressure compensation and water retainment valve  4102 . 
         [0132]      FIG. 50  shows a perspective side view of an embodiment that enables mechanical engagement of the water retention valve with the drip emitter with area that holds the water retention valve visible. In this figure, water retainment valve  281   a  is mechanically engaged (as per the water retainment valve slot  200   a  as shown in  FIG. 57 ) before enclosing the drip emitter in an enclosing pipe via for example teeth  4701  (as shown in  FIG. 60-61 ). 
         [0133]      FIG. 51  shows a perspective view from a different angle with respect to  FIG. 50 . In this figure, Flaps  401   a  are shown in water retention valve  281   a.    
         [0134]      FIG. 52  shows a side view of an embodiment that enables mechanical engagement of the water retention valve with the drip emitter wherein the water retention valve is mechanically engaged to the drip emitter. 
         [0135]      FIG. 53  shows an end view of the drip emitter with a mechanically engaged ventable embodiment of the water retention valve. 
         [0136]      FIG. 54  shows a side view of the drip emitter with a mechanically engaged ventable embodiment of the water retention valve showing flaps  401   a.    
         [0137]      FIG. 55  shows a top view of the drip emitter with a mechanically engaged ventable embodiment of the water retention valve. 
         [0138]      FIG. 56  shows a side cross-section view of the drip emitter along the section line of  FIG. 55 , with a mechanically engaged ventable embodiment of the water retention valve  281   a,  with water flow path where water moves from left to right in the figure during irrigation and exiting via flaps  401   a.    
         [0139]      FIG. 57  shows an empty area that is configured as water retainment valve slot  200   a,  into which water retainment valve is for example injected in. 
         [0140]      FIG. 58  shows a top view of  FIG. 55  without the mechanically engaged water retention valve. 
         [0141]      FIG. 59  shows a side view of the drip emitter showing water retainment valve slot  200   a  without a mechanically engaged water retention valve inserted. 
         [0142]      FIG. 60  shows a perspective view of an embodiment of mechanically engaged water retention valve  281   a  having flaps  401   a  and teeth  4701  for mechanical engagement with the drip emitter. 
         [0143]      FIG. 61  shows a side view of the mechanically engaged water retention valve of  FIG. 60  having teeth  4701  for mechanical engagement with the drip emitter. 
         [0144]      FIG. 62  shows an end view of the mechanically engaged water retention valve of  FIG. 61 . 
         [0145]      FIG. 63  shows an opposing side view of the mechanically engaged water retention valve of  FIG. 61  showing flaps  401   a.    
         [0146]      FIG. 64  shows a bottom view of the mechanically engaged water retention valve showing teeth  4701  for mechanical engagement to the drip emitter via water retainment valve slot  200   a  as shown in  FIG. 59  for example. 
         [0147]    While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.