IL30187A - Irrigation conduit - Google Patents

Description

IRRIGATION CONDUIT R A DUIT AND COMPOSITION AND METHOD FOR PRODUCING SUCH The invention is directed to a composition and the use of this composition to the production of particular articles of manufacture commonly known as irrigation or soaking conduits. According to the proce ss of the invention, a foamable thermoplastic re sin composition is extruded in such a way so as to obtain a conduit having a wall structure composed of a cellular body of interconnecting pore s .

During the extrusion proces s, the outer surface of the conduit is treated in such a way so as to produce an outer surface or skin which is substantially impervious to water. The conduit thus prepared is then provided with a score line or score line s which de stroy the water impervious nature of the outer surface. In use, the se conduits are maintained under water pressure which causes the water to seep through the pores of the wall and ultimately to the score lines which permit the water to seep from the conduit. The irrigation or soaking of lands is thereby obtained.

The invention de scribed in greater detail herein is directed to irrigation conduits and methods and compositions for producing the se conduits. The irrigation or soaking of cultivating lands over the years has presented some unique problems perhaps only appreciated by those who are directly concerned with this area.

Because of these problems such work has gone into the development of water carrying systems which will operate automatically and efficiently. The continued search for new devices and new materials to produce these devices has been stimulated in recent years since many areas, which normally receive adequate rainfall during the cultivating months, have experienced lesser amounts of rainfall than normal. As a result there has been considerable economic loss due to the combination of inadequate rainfall and inefficient irrigation systems.

Over the years various conduits ranging from sprinkling hose s to* keeping hoses have been produced and have appeared on the market. Since each of the conduits presently used has some particular disadvantages, additional sophisticated devices and attachments have been proposed for modifying the existing structures. In addition, various materials have been substituted and used in attempts to overcome problems associated with still other type conduits.

Devices which have been developed for the irrigation of cultivating lands or more specifically for supplying, water to farmland, lawns and the like, fall within two categories. In the first category are included sprinkling devices which spra wate r onto the area to be watered in the form of a stream, sprinkle or mist. ■ The second category of devices is a conduit which does not sprinkle or spray the water but merely allows the water to seep through the surface of the conduit and along its entire length by means of pe rforations. The areas around the conduits are the reby watered or soaked.

The pre sent invention is concerned with the second category of devices more commonly referred to as " soaking conduits" . Soil soaking hoses or conduits in themselves are well known as evidenced by the fact that various U. S. patents have issued which are spe cifically directed to this type device. As e xample s of those patents may be noted U. S. Patent Nos . 1, 989, 427, 2, 595, 408 and 2, 807, 505. One of the first soaking devices used which has found limited succes s is a hose fabricated from canvas . This product and some of its shortcomings are described in U. S. Patent No. 2, 807, 505 referred to above . This patent in turn de scribe s a soaking device which is stated to overcome some of the dis advantages of the canvas soaking hose .

The hose of the above -mentioned patent ss eks to duplicate the highly effective soaking characteristics of the canvas hose and at the same time eliminate the inherent kinking, rotting or creasing drawbacks of that type hose . The hose described in U. S. Patent No. 2, 807, 505 is produced from a foamable plastic which upon extrusion give s the hose a wall structure composed of a multiplicity of inte rconnected irregular shaped pores . According to the de scription of the patent, the water contained in the hose is forced by the pres sure of the water entering the hose from the source s through the pore s of the wall structure and out of the porous exterior surface. As can be readily appreciated a hose functioning in this capacity must pos sess a structure sufficient to withstand the internal pressures of water since order to obtain this flow the hose must be maintained under constant pressure.

The most significant problem which must be overcome in the production of a hose which is utilized in this manner is to obtain a hose structure which will not only sustain the afore- ' mentioned pressures but which will also permit the even distribution of water over the entire length of the hose. For example, when one considers the use of a length of hose measuring 100 feet or more, the pressure necessary to caus the flow of the water through the wall structure must be sufficiently distributed throughout the entire length of the hose, otherwise, that portion of the hose closest to the supply of water would release large amount of the water thereby reducing the pressure to such an extent that there would not be sufficient pressure in that portion of the hose farthest from the . supply to cause the water to flow through the walls. This in effect would lead to substantial soaking in one area with perhaps only limited, if any, soaking in the area farthest from the source of water. This, of course, is most undesirable both from an economic standpoint and from the handling aspect.

Therefore, it- is quite apparent that although these conduits appear superficially to be quite simple in structure, this initial impression is quite deceiving and when the mechanics, the economics and the handling requirements are considered, it is quite clear that the production of a conduit nece ssary to ie st all of the es saitial prerequisites is in fact quite complicated.

For example, the problem of obtaining an even distribution of water over the entire length of a conduit measuring 100 feet or even 500 feet in itself has been a rather perplexing problem.

The conduit must be capable of passing approximately the same amount of water at the portion of the conduit farthest from vhe supply as that passed at the portion closest to the water supply. The water seepage can be controlled and an even distribution of the wate r can be attained with the conduits of the pre sent invention because of applicant' s discovery.

The present invention as earlier stated has as one of its objects the production of a soaking conduit which not only possesse s anti-deterioration properties, i. e.' rotting,' but which also permits the even soaking of areas without the attendant disadvantages of the prior art conduits.

The conduits of the present invention permit the even distribution of water over large areas without the necessity of continual observation or handling since the conduit as produced permits the even and gentle flow of water over the entire, area j covered by the conduit. ' I i The objects as above mentioned are made possible only through the obtention of more intermediate objects which include the formulation of thermoplastic compositions which in turn give the final product of the invention the physical and mechanical prope rties which are the nece s sary prerequisite s for the ultimate and efficient use of the conduit. More specifically, the compositions are those which when extruded and treated yield conduits having walls which are in the form of a porous structure and composed of a multiplicity of interconnected pores of such . size, distribution and degree of interconnection that water under pres sure within the conduit will flow through these pore s and eventually through scorings which are provided in the otherwise water impe rvious or water impermeable exterior surface of the wall structure.

One of the primary objects of the invention is to produce a conduit posses sing a wall structure which is composed from the . interior to exterior of a cellular plastic material. Moreover, the conduit is prepared in such a manner that the exterior surface of the conduit is substantially water impervious or water impermeable . The outer surface of the conduit is provided with a score line or score lines at a predetermined location or at predete rmined locations which de stroy the water impervioua nature of the oute r surface in that or those locations.

In addition, the invention has as one of its objects the method of preparing the above -described conduits from the previously mentioned compositions.

In accordance with the invention there is provided a compo sition of matte r for use in the production of irrigation conduit comprising a the rmoplastic re sin, , an agent capable of releasing gases upon heating and an oil.

The invention also re side s in a method of forming a conduit for use as a soaking device which comprise s the steps of extruding a hot hollow conduit from a foamable thermoplastic re sin; cooling the external wall of said conduit within a short time after it is extruded to form a water-impe rvious, non-porous external surface; cooling and hardening the conduit and making at least one score line in the impervious, non-porous external surface to a depth at least sufficient to destroy the wate r -impe rvious nature of said surface.

The invention also provides a conduit for carrying a liquid which comprise s a wall structure enclosing an area for the pas sage of said liquid, said wall structure comprised of a cellular plastic material having an outer surface which is normally impervious to water, said outer stirface pos se s sing at least one score line, said score line penetrating said outer surface to a depth sufficient to de stroy the water-impervious nature of the outer surface .

Similarly the invention provide s a soil soaking hose wherein the walls of said hose are comprised of cellular polyethylene, the outer surface of the walls being substantially impervious to water, said outer surface pos se ssing at least one score line which penetrates said surface to a depth sufficient to destroy the water -impervious nature of the outer surface, said score line extending the entire length of said hose, and wherein the walls of said hose are of sufficient thickness to withstand pressures necessary for normal operating condition .

The objects of the invention are accomplished generally by extruding a foamable composition comprising a thermoplastic re sin, an agent which releases gases, or more commonly referred to as a blowing or foaming agent, and an oil through a die to . obtain a conduit of a predetermined shape.

At the head of the extruder is attached the die carryin a cooled sizer which in turn cools, sizes and hardens the exterior surface of the conduit as it comes from the die. In this manner a skin which is impe vious to water is pa-oducod on the outer surface. Air is forced through the extruded conduit as it enters the sizer to ensure that the conduit is expanded so as to come into intimate contact with the sizer thereby assuring the obtention of the water -impervious outer surface or skin. The conduit is cooled and tlaen brought into contact with a scoring device which produces a score line or slit in the outer surface which may penetrate the wall to a depth of one half the wall thickness.

The score line may run continuously along the length of the hose and longitudinal to the axis of the conduit or it may be non- continuous or have othe r configurations which are exemplified in the drawing of this specification.

The extruded conduit may then be cut into desired lengths and provided with the conventional coupling devices for attachment either to othe r sections of conduit or to the faucets which supply the water. Since one end of the conduit must be sealed to insure that the leakage will take place along the length of the conduit, the coupling device may be fashioned so as to operate as eithe r a means of attachment for an additional section of hose or as a means to fit a cap which will seal the end of the conduit. Of course, the walls of the hose at the end to be sealed may be fused together thereby creating the nece s sary seal. The fusing may be performed either mechanically or physically, that is, by the use of various mechanical pinching devices or by simply heating the conduit at the appropriate place and heat fusing the walls together.

A more complete understanding of the products of the invention' and the method of manufacturing such can be obtained by a consideration of the accompanying drawing, in which: Figure 1 is a flow diagram of the primary steps of the proce s s for the manufacture of the conduits of the invention; Figure 2 is a view of tubular or hose form of the conduit showing the scoring lines running continuously and longitudinal to the axis of the hose and positioned at the quarter marks of the circumference of the hose ; Figure 3 is a cros's-sectional view of the hose of Figure 2 when that hose is cut along line 3 - 3; Figure 4 is the view of Figure 3 when the hose is filled with water and the sco re lines are partially opened by the pressure of the water on the walls of the hose which in turn permits the seepage of the water from the hose ; and 6 Figure s ^ and depict the variations in the pattern of the scoring which are pos sible and of course, are not to be construed as limiting.

Referring to the drawings in more detail, the conduits of the pre sent invention are shown for example in Figure 3 and as . explained in Figure 4, po s ses s a cellular structured wall through which water unde r pre s sure seeps. Since the exterior surface or skin is not pervious to water, the water must- seep or be pres sured to flow toward the score lines (or slits) de signated 9 as "S (. Since the score line s de stroy the water-i mpervious nature of the outer surface, the water seeps through these lines and then flows from the conduit as shown in Figure 4.

Although the conduit is drawn in tubular form and po sses sing four score line s (running the entire length of and . longitudinal to the axis of the conduit) it is clear that the hose may be of many shape s, for example, square, spherical, etc. and the numbe r of score lines can be varied depending upon the amount of water the worker desire s to have flow from the conduit.

The same is equally true with re spect to the depth of the score.

The depth of the score may range from the me re slitting of the water -impervious skin to as much as 50% of the wall thickness. Applicant has found that a tubular conduit having four score line s located at the quarter marks of the circumference, each having a depth of from 20 to 50 % of the wall thickne s s operates particularly well from the standpoint of soaking time s and water flow. Of course, the wall thickness must be of sufficient size to withstand the pre s sure s generated within the conduit. For example, a 500 foot length of a tubular conduit produced from medium density polyethylene having a one inch outside diameter and a wall thicknes s of 3/l6 of an inch operates quite effectively unde r a pre s sure of 60 lbs . pe r square inch. Accordingly, the worker in the art' after considering his particular requirements can determine the size conduit, the number of score line s and the depth of the score line s nece ssary to perform the de sired funct ion.

A wide variety of thermoplastic re sin materials can be. used in the formation of the irrigation conduits of the present invention. Ethylene polymers and copolymers (such as ethylene - and propylene polymers and copolyme rs give particularly good quality conduits . Othe r plastic materials such as the semi-flexible forms of nylon and vinyl resins and in particular, vinyl chloride polymers which are modified with small amounts of vinyl acetate can be used. The only prerequisites for the plastic material is that it be foam extrudable and pos ses s a . structure after extrusion which although flexible to a certain extent, is sufficiently rigid to retain the shape of a conduit even when not in use and sufficiently rigid to virtually eliminate the problem of kinking when the conduit is laid out for use. Medium and low density polyethylene s have been found to be particularly suitable for the purpose since the se polyme rs are foamable, have the prerequisite physical prope rtie s, are particularly re sistant to deterioration and give the most uniform porosity when foam extruded. The conduits produced from the formulations of the invention pos ses s a balance of flexibility and rigidity which allows them to be easily handled and placed while at the same time allows for its expansion unde r the operating pre ssure s. ) . . In addition, the conduits are sufficiently rigid to maintain their shape when not in use and at the same time of siifficient strength to pe rmit normal handling together with the capacity to take impact or support loads without fear of irreparable damage.

The second ingre ent o t e resin formulations wh ch n effect creates the foamed or porous cellular structure is an agent which releases gases when exposed to heat. These agents, commonly referred to as "blowing agents", by the evolution of gas cause the semi- solid and hot plastic material to expand so as to form the porous structure. A number of different compounds perform in this manner and as exemplary may be mentioned sodium bicarbonate, · ammonium bicarbonate, ammonium carbonate, ammonium sesquicarbonate, etc. In addition, to those agents mentioned such organic agents such as N, N1 dinitrosopentamethylenetetramine, N, N' - dimethyl-N, N1 dinitrosoterephthalamide, benzene-1, 3 - disulfonyl hydrazide, azobisforamide and like compounds. The formulation can contain from 1 to 3% by weight of the thermoplastic resin weight and preferably from 1.5% to 2% by weight.

In addition to the above, a small amount of lubricating or machine oil is included in the formulation. The inclusion of ■ the oil has a marked effect on the ease of extrusion and the properties of the final conduit. Although applicant does not wish to be limited to his theory as to how the oil functions in the formulation since it is only speculation, the oil appears to function in various capacities. It most probably serves as a lubricant during the extrusion procedure;; it permits the obtention of an even coating of the blowing agent in each of the resin pollets and since the thermoplastic granule s are coated very lightly with the oil during the mixing proce s se s, the re sin granules upon being melted and extruded although they co mbine to form the de sired structure, do not knit as tightly as they normally would without the oil and the refore permits water seepage through the wall · structure in a more uniform manner. The combination of the resin, the blowing agent and the oil and in particular the combination of low density or medium density polyethylene, sodium bicarbonate and a nephthenic machine 'oil having as Saybolt Seconds Universal viscosity of 100 at 100°F yields a conduit with a uniform porous structure which, when slit according to the invention and used as de scribed produces a uniform distribution of the water to the area to be soaked.

In addition to the above -mentioned oil may be used oils having the following characteristics : Gravity, °AP1 31. 8 33. 8 Clash °F COC 375 395 Cold Te st °F +6 +4 Viscosity, SSU at 100 105. 1 109. 3 Visco sity Index 106. 4 110. 5 Color ASPM D-1500 3. 5 2. 5 Typical naphthenic lubricating oils derived from naphthenic crudes such as oils having -the following characteristics can also be used: Lubricating oil 3 4 Gravity, °AP1 23.2 24.4 Viscosity, SSU/100°F 150 99.89 Viscosity, SSU/210°F 41.1 37.7 Power, °F +10 -55 Specific Dispersion 129.6 132.8 % paraffin 7.7 4.

Naphthenes 5.1 5.0 A part cularly good oil is a refined lubricating oil which has the following characteristics : Viscosity at 100°F (SSU) 107 Viscosity at 210°F (SSU) 39.5 Viscosity Index 80 13% aromatic s an average of 1.2 aromatic rings per molecule and 1.6 nephthylene rings per molecule with an average molecular weight of 33 The oil as earlier stated is included in small amounts, for example, a formulation containing 50 pounds of medium density polyethylene, 12 ounce s of sodium bicarbonate will contain about 24 drops of oil. However, as is obvious, this amount of oil ope rate s quite effectively for this formulation and the worker in the art will readily realize that ce rtain adjustments in this amount can be made depending of cour se on the product de sired, the ■ visco sity of the oil, the type re sin utilized and the extrusion conditions. However, in any instance the oil content of the formulation does not exceed 100 drops per 50 pounds of re sin or is le ss than 10 drops fo r the same amount of re sin.

As will be appreciated additional agents, for example, coloring agents, mildew growth re sisting agents, fillers, etc. can be added to the formulations .>o long as the agents do not change the basic characteristics of formulation and do not effect the eventual obtention of conduits posse ssing a uniform distribution of pore s or cells .

As depicted by the flow diagram of Figure 1 of the drawing, a mixture of the re sin granules, the blowing agent and the oil is placed in a mixer which by a tumbling and mixing action insures Preferably the resin is laced in the mixer first and then the oil is added. The two ingredients are mixed for a time s\;fficient to obtain the coating as above described. The blowing agent is then added and the mixture again mixed until the resin granule s or pellets each have a un iform coating of the blowing agent.

The material is then ready for extrusion and- ancillary treatments so as to produce the de sired conduit. The preferred extrusion conditions and ancillary treatments will be set forth in the specific example s.

The extrude r used is of a conventional type . The dies used are also conventional in nature and modified only to the extent that there is attached directly to the die a sizer preferably made of aluminum. The sizer is designed to be maintained at a cool temperature and acts to harden and cool the plastic being extruded and to thereby obtain the outer water-impervious skin.

Having thus described the invention generally, the inventipn will be de scribed, mgrg §p§ci£ig¾lly to s§t forth the prefe rred embodiments in the following examples : EXAMPLE I Mixing of Materials 50 pounds of low density polyethylene having a specific gravity of 0. 910 in pellet form are placed in a mixer which operate s by tumbling action. To the polyethylene is then added 24 drops of naphthenic oil having a Saybolt Seconds Universal viscosity of 100 at 100°F. The polyethylene and the oil are then mixed from 4 to 6 minutes after which time the polyethylene pellet a e cove red with a fine coating of the oil. There is then added to the mixer 12 ounces of sodium bicarbonate and the mixing is continued until the polyethylene pellets are evenly covered with . n accomp s e e ormu a on is ready for extrusion. ' Extrusion The extruder is of a conventional type and operates at pre s sure s which are nece s sary for the extrusion of the particular plastic materials used. At the head of the extruder ■ is attached a die which, as is well known, shape s the material being extruded into the de sired form. Attached directly to the die at its exit point is an aluminum size r which is designed to have a contin;ious flow of cold water which maintains the sizer i a cool state.

The extruder poss esse s an electric panel where the various barrel temperature s can be controlled. The extruder conventionally has three heated zo ne s. The initial zone which is directly below the feeding inlet is set at a temperature of 300 to 350°F. The second zone is set within the range of 320 to 340°F and zone three, which is the zone farthest from the feeding zone, is set for a temperature of 340 to 350° F. The head of the extrude r is maintained at a temperature of 340 to 360°F and the temperature of the die in kept between 350 and 360°F. The material is then loaded into the hopper of the extruder and then fed into the extruding chamber.

Afte r the material has reached the appropriate temperature s the mate rial is extruded through the head of the extrude r and into the die. As the material exits from the die in conduit form, air pres sure at approximately 10 pounds is introduced inside the conduit in order to expand the conduit so as to put the exterior walls of the conduit in intimate contact with the cooled sizer.

The size r cools and hardens the exterior wall of the conduit and as a consequence creates a skin or outer surface on the hose which is free of any cellular structure and therefore, give s the conduit a water-impervious surface .

From the sizer the ho se enters a water tank, whe re it is completely submerged in the water contained therein. The conduit is cooled and further hardened by this treatment. The extruded conduit is then run through a slitting or scoring device bearing tool steel blade s which are adjustable to permit the scoring of the conduit to various depths. The' slitting device is ■ so de signed so as to enable at least one and up to six score line s to be produced in the ho se . Of course, the hose may be run through the slitting device as many time s as neces sary to obtain the de sired number of score lines . The conduit according to this example is scored at each quarter mark of the circumference of the conduit. The depth of the slit is 20 % of the wall thickne s s . The pipe produced by this example is tubular in form and has a one inch outside diameter with approximately a 3/l6" wall thickne s s . _ » V c score -'line s extended- ,cpiitmuo.uj3ly''.£p r i the : eriti-r e length of the hose which was approximately 100 feet and ran longitudinal to the axis of the conduit. The conduit is then /ittcd with various coupling devices in order to set the conduit in operation. One end of the conduit is fitted with a coupling device for fastening or connecting a faucet or water supply means. .

The other end is fitted with a coupling device which is fitted with a cap in order to completely close off that end of' the conduit.

Te sting of Prepared Conduit The conduit was then laid out, and the coupling end connected to a faucet. The water leakage for the conduit was measured under certain water pre ssures . The following table sets forth the particular data determined for this conduit.

P. S. I. on Hose Length of Ho se Minute s of Te st Gallons of water leakage 100 ft. 60 minutes Gallons 72. 0 100 ft. 60 minutes Gallons 88. 5 100 ft. 60 minutes Gallons 109. 5 100 ft. 60 minutes Gallons 147. 0 40 : 100 ft. · 60 minutes Gallons 186. 0 50 100 ft. 60 minutes Gallons 234. 0 60 100 ft. 60 minutes Gallons 303. 0 EXAMPLE II A conduit was prepared according to the proces s as set • forth in Example I with the exception that instead of low density polyethylene, a medium density polyethylene having a specific gravity of 0. 926 was used.

EXAMPLE HI A conduit was prepared according to the proce ss of Example I with the exception that the score line s or slits were made to a les se r depth. The score line s were of such depth that they only penetrated -the outer water -impe rvious skin.

EXAMPLE IV ' Example I was repeated with the exception that the conduit made measured 2" in outside diameter and posse ssed a wall thickne s s of. approximately l/4".

EXAMPLE V Example I was repeated with the exception that only one scoring was made and this scoring was spiral and ran the entire length of the conduit. The conduit obtained is illustrated by Figure 5 of the drawing.

EXAMPLE VI I Example was repeated with the exception that the scorings were made so as to be circumferential and located at distance s evenly spaced apart. The circumferential scores were made so as to be l/2" apart. The conduit as obtained by this example is illustrated by Figure 6 of the drawing.

EXAMPLE VII Example II was repeated with the exception that only one score line was made longitudinal to the axis of the conduit. The depth of the score line was approximately. 50% of the wal^ thicknes s.

Since many modifications and variations of the pre sent invention are pos sible in the light of the above teachings, it is, therefore, fo be understood that the se modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims (2)

1. WHAT IS CLAIMED IS s - 1. A soil soaker hose comprising: an elongated lexible conduit of a length many times its diameter whereby it may be arranged, in contact with the ground in any desired configuration to soak soil over a predetermined large area , said conduit having a generally cylindrical wall struoture of water pervious cellular foamed material; the outer surface of said wall structure having a water impervious skin defining said, outer surface; the inner surface of said wall struoture being completely free of impervious skin whereby all the cells of said material at said inner surface, are open to the interior of said hose so that water therein may freely enter . said wall struoture through the e tire inner surface of said wall structure; and at least one narrow and substantially continuous slit through said outer skin extending substantially from end to end of said conduit, said slit extending into but not through said wall structure, to provide only restricted egress for water along the length of said hose.
2. 2. A hose as defined in Claim 1 wherein the outer diameter of said hose does not exceed about 2 inches and wherein the length thereof is greater than 10 feet 3· A hose as defined in Claim 1 wherein the depth of said slit ranges from about 20 percent to about 50 percent of the wall thickness. , 4. A hose as defined in Claim 1 provided with a plurality of said slits spaced about the periphery thereof. 5. A hose as defined in Claim 1 wherein said slit extends helically around the outer surface thereof* COHEN ZEDEK & SPISBACH P.O.BOX 33116, TEL AVIV ATTORNEYS FOR APPLICANTS .