U.S. patent application number 11/437668 was filed with the patent office on 2006-12-07 for drip irrigation system.
This patent application is currently assigned to NETAFIM, LTD.. Invention is credited to Rafi Golan, Ammon Meisless, Eli Vered.
Application Number | 20060272726 11/437668 |
Document ID | / |
Family ID | 33416477 |
Filed Date | 2006-12-07 |
United States Patent
Application |
20060272726 |
Kind Code |
A1 |
Golan; Rafi ; et
al. |
December 7, 2006 |
Drip irrigation system
Abstract
Low-pressure drip irrigation system, comprising a distribution
pipe made of thin-walled sleeve collapsible when empty and designed
to operate under hydraulic head up to 3 m H.sub.2O, having a
plurality of holes in the walls thereof, a plurality of branch
tubes equipped with low-pressure drip emitters; and a plurality of
connectors connecting the branch tubes to the holes of the
distribution pipe. The sleeve material is opaque and reflecting the
solar radiation so that the natural growth of microorganisms and
algae in the irrigation water is suppressed, and the pipe is not
heated more than 35.degree. C. above the ambient air temperature.
The irrigation system is assembled in the field from components of
a kit by deploying the distribution pipe, filling it with water,
cutting the holes by means of a special hand-held tool, inserting
the connectors into the holes, and assembling the branch tubes with
the connectors.
Inventors: |
Golan; Rafi; (Ramat Hagolan,
IL) ; Vered; Eli; (Emek Hefer, IL) ; Meisless;
Ammon; (Emek Hefer, IL) |
Correspondence
Address: |
BROWDY AND NEIMARK, P.L.L.C.;624 NINTH STREET, NW
SUITE 300
WASHINGTON
DC
20001-5303
US
|
Assignee: |
NETAFIM, LTD.
Tel Aviv
IL
|
Family ID: |
33416477 |
Appl. No.: |
11/437668 |
Filed: |
May 22, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10431575 |
May 8, 2003 |
7048010 |
|
|
11437668 |
May 22, 2006 |
|
|
|
Current U.S.
Class: |
138/119 ;
138/118; 138/145; 239/542; 285/192 |
Current CPC
Class: |
A01G 25/02 20130101;
Y02A 40/22 20180101; Y02A 40/237 20180101 |
Class at
Publication: |
138/119 ;
138/118; 138/145; 239/542; 285/192 |
International
Class: |
F16L 11/00 20060101
F16L011/00 |
Claims
1. Low-pressure drip irrigation system, comprising: a distribution
pipe made of thin-walled sleeve collapsible when empty and designed
to operate under hydraulic head up to 3 m H.sub.20, having a
plurality of holes in the walls thereof, and having an upstream end
connectable to a source of water, a plurality of branch tubes
equipped with low-press drip emitters; and a plurality of
connectors connecting said branch tube to said holes of said
distribution pipe.
2. The irrigation system of claim 1, wherein, said connectors have
a nipple part for connecting to said branch tubes and a base part
for connecting to said holes, said base part having a first and a
second protruding collar and a narrow neck therebetween, each of
said connectors being mounted in one of said holes with the first
collar inside the distribution pipe, so that the edge of the hole
tightly embraces the neck of the connector, thereby securing the
connector to said distribution pipe.
3. The irrigation system of claim 2, wherein said thin-walled
sleeve is capable of elastic expansion at least around each of said
holes so as to allow penetration of said first collar through said
hole when the respective connector is urged into said hole while
said distribution, pipe is filled with water, thereby enabling the
manual assembly of said irrigation system in the field.
4. A connector with an axial bore for use in the irrigation system
of claim 1, said connector having a base part mountable to a hole
in said distribution pipe and a nipple part mountable to one of
said branch tubes, said base part comprising: a frustum section
starting with an annular edge defining one end of said axial bore
and smoothly flaring into a fast collar, said frustum part being
adapted to penetrate said hole by elastically expanding the edge
thereof when the connector is urged therein; a neck section
adjacent said first collar and narrower than said first collar,
adapted to accommodate the edge of said hole, when said first
collar is inside the distribution pipe; and a second collar section
spaced from said first collar by said neck section and wider than
said first collar so as to prevent further penetration of said
connector into said distribution pipe.
5. The connector of claim 4, wherein said neck is wider than said
hole in non-expanded state so as to fit tightly to the edge of said
hole when said first collar is inside the distribution pipe.
6. The connector of claim 5, wherein said axial bore of diameter D,
said hole has diameter between 0.8 and 1.0D, said first collar has
diameter between 1.4 and 1.7D, said neck has diameter between 1.1
and 1.3D, and said second collar has diameter greater than
1.9D.
7. The connector of claim 6, wherein said diameter D is between 10
and 45 mm.
8. The connector of claim 4, wherein, said neck comprises a
threaded portion and said second collar is formed as a separate
member internal thread matching said threaded portion so that said
second collar can seal said edge of the hole to said first collar
by tightening up.
9-21. (canceled)
22. A water-irrigation distribution pipe made of a sleeve
collapsible when empty, with diameter of at least three inches when
filled with water, and operable under hydraulic head up to 3 m
H.sub.2O, said sleeve being made of material adapted to reflect at
least partially solar radiation so that, at flow velocity of
irrigation water in the pipe between 0.02 and 0.1 m/s, said pipe is
not heated more than 35.degree. C. above the ambient air
temperature wherein said pipe provided with markings indicating
places where holes for connecting branch tubes are to be made.
23. The distribution pipe of claim 22, wherein said markings
comprise recesses providing stable positioning of a cutting tool
for cutting said holes.
24-32. (canceled)
33. The irrigation system of claim 1, wherein said distribution
pipe is adapted for cutting therein said holes when said
distribution pipe is filled with water under pressure about 3 m
H.sub.20.
34. The irrigation system of claim 1, further comprising a gravity
filtering tank connectable to a source of water for filtering said
water, connected to said upstream end of said distribution
pipe.
35. The irrigation system of claim 34, further comprising an
automated system for the regulation of the hydraulic head of the
irrigation water in said gravity filtering tank.
36. The irrigation system of claim 35, wherein said automated
system comprises a pressure sensor disposed at the distal end of
one of said branch tubes, and said hydraulic head is regulated in
dependence on readings obtained from said sensor.
37. A kit for assembling a low-pressure irrigation system,
comprising at least two of the following components: a distribution
pipe made of thin-walled collapsible sleeve designed to operate
under hydraulic head up to 3 m H.sub.20, having holes or adapted
for cutting therein holes; a plurality of branch tubes equipped
with low-pressure drip emitters; a plurality of connectors, adapted
to connect said branch tubes to said holes in said distribution
pipe; and a hand-held tool for cutting said holes in the
distribution pipe.
38. The kit of claim 37, wherein said distribution pipe is provided
with markings indicating places where said holes are to be
made.
39. The kit of claim 37, wherein said distribution pipe is adapted
for cutting therein holes when filled with water.
40. The kit of claim 37, wherein said distribution pipe comprises
an internal membrane extending along the whole length of the pipe
and dividing the cross-section thereof into two chambers, said
internal membrane being adapted to filter the irrigation water
passing between said two chambers.
41. A branch tube with low-pressure drip emitters and a connector
assembled thereto, for use with the irrigation system of claim
1.
42. A hand-held tool for cutting the holes in the distribution tube
of claim 1, comprising: a tubular cutter with thin annular cutting
edge formed with plurality of teeth, and a handle attached to said
tubular cutter, said tool being adapted to cut said holes by urging
the cutter to said distribution tube when the latter is filled with
water, and rotating the tool.
43. The hand-held tool of claim 42, wherein said handle has a
through axial bore in communication with the inside of said tubular
cutter, and said tool further comprises a plunger movably
accommodated inside said tubular cutter, with a tail extension
obtained through said axial bore, so that when cut-out material
from the wall of said distribution tube accumulates in the tubular
cutter, said material can be expelled by pressing said tail
extension and moving the plunger.
44. The hand-held tool of claim 43, wherein said tubular cutter is
firmly attached to said handle and said tool is adapted for
rotation by hand.
45. The hand-held tool of claim 44, further comprising an electric
drive, said tubular cutter being adapted for rotation by means of
said drive.
46. A method for assembly of a low-pressure drip irrigation system
from all the components of the kit of claim 37, in an irrigation
field, comprising: deploying said distribution pipe in the field
and connecting it to a source of water ensuring 3 m H.sub.20
hydraulic head with respect to the field level; filling the
distribution pipe with water; assembling one of the branch tubes
with one of the connectors; cutting a hole in said distribution
pipe by means of the hand-held tool; inserting said connector into
said hole of the distribution pipe thereby attaching said branch
tube to said pipe; and repeating the three last steps for the next
branch tubes.
Description
[0001] This is a division of co-pending parent application Ser. No.
10/431,575, filed May 8, 2003.
FIELD OF THE INVENTION
[0002] This invention relates to drip irrigation systems, more
particularly to low-pressure irrigation systems.
BACKGROUND OF THE INVENTION
[0003] Known types of drip-irrigation systems use pressurized water
sources of about 2 ata and more. Distribution pipes, fittings and
valves in such systems are made of strong and relatively thick
plastic materials. These systems are essentially independent on the
field topography. However, pressure losses along their branching
tubes with drip emitters are large. In order to achieve uniform
dripping, special pressure-compensated emitters are used. These
systems involve substantial investment costs and power consumption
in operation.
[0004] On the other hand, systems for flood furrow irrigation are
traditionally applied on large areas. They include open
distribution channels and branching furrows made in the fields.
Since water in such system flows only due to the gravitation force,
all channels and furrows are maintained with proper weak
inclination. The flood irrigation requires less investment costs
but the spending of water is huge. Moreover, the freely flowing
water causes surface erosion and salinization of soils. Since
recently, distribution channels are replaced by soft distribution
pipes of large diameter with a plurality of openings which help to
deliver irrigation water to the furrows without losses, pouring the
water at the beginning of the furrow through the openings in the
distribution pipe. These pipes are quite cheap and easily deployed;
they may be used for one season and disposed of. However, water
expenses still remain high.
SUMMARY OF THE INVENTION
[0005] According to the present invention, there is provided a
low-pressure drip irrigation system, comprising:
[0006] a distribution pipe made of thin-walled sleeve collapsible
when empty and designed to operate under hydraulic head up to 3 m
H.sub.2O, having a plurality of holes in the walls thereof, and
having an upstream end connectable to a source of water;
[0007] a plurality of branch tubes equipped with low-pressure drip
emitters; and
[0008] a plurality of connectors, connecting the branch tubes to
the holes of the distribution pipe.
[0009] The irrigation system further comprises a gravity filtering
tank connectable to a source of water, the tank being connected to
the upstream end of the distribution pipe.
[0010] The irrigation system is preferably controlled by an
automated system for the regulation of the hydraulic head of the
irrigation water in the gravity filtering tank. This automated
system includes a pressure sensor disposed at the distal end of one
of the branch tubes, and the hydraulic head is regulated in
dependence on readings obtained from the sensor.
[0011] The connectors used for assembling the above irrigation
system have a nipple part for connecting to the branch tubes and a
base part for connecting to the holes in the distribution pipe. The
base part has a first and a second protruding collar and a narrow
neck therebetween, the holes in the distribution pipe have
diameters less than diameters of the respective necks. The
connectors are each mounted in one of the holes with the first
collar inside the distribution pipe so that the edge of the hole
tightly embraces the neck of the connector, thereby securing the
connector to the distribution pipe.
[0012] As an alternative embodiment, the neck of the connector may
comprise a threaded portion while the second collar is formed as a
separate member with internal thread matching the threaded portion
so that the second collar can seal the edge of the hole to the
first collar by tightening up.
[0013] According to a second aspect of the present invention, there
is provided a thin-walled sleeve for use as distribution pipe, e.g.
in the above irrigation system. The flow through the distribution
pipe, under relatively low pressure and limited discharge through
the drip emitters, is rather slow, typically between 0.02 and 0.8
m/s. Under such conditions, with conventional distribution pipes
used in flood furrow irrigation, solar radiation in the field,
penetrating through the pipe walls, promotes intensive growth of
microorganisms and algae that are naturally present in the
irrigation water. Such growth would soon lead to clogging of the
drip emitters which usually have narrow water-passage labyrinths
and small discharge openings. However, the distribution pipe of the
present invention is made of opaque material that prevents light
from entering into the pipe, thereby suppressing the growth of
algae. Good results have been obtained with materials effectively
stopping the visible and UV radiation and transmitting less than 5%
of the IR radiation.
[0014] Another problem related to the slow water flow in the
distribution pipe is heating by the sun radiation. High temperature
of the water in the pipe reduces the strength of the sleeve
material and accelerates aging. For this reason, the sleeve
material of the present invention is not only opaque but also is
designed to reflect a major part of the sun radiation, about 20%
and more. Thus, the distribution pipe, even with the small flow
velocity mentioned above, is not heated to more than 30-35.degree.
C. above the ambient air temperature. Notably, this problem does
not exist with higher pressure pipes and with the furrow irrigation
pipes where flow velocity is much higher and the running water
cools the pipes.
[0015] The pipe material is extendable in the area of the holes
about 1.6 times of their initial diameter, but should not be
over-extendable, in order to hold the connectors up to internal
pressure at least twice the operation pressure. The pipe material
is also strong and deformable enough to endure overriding by
wheeled vehicles with rubber tires when collapsed empty on
non-rocky soil. Thus, it was found that material with total
(elastic plus plastic) elongation before breaking of about 7.5
times would serve for more than one season of irrigation. Another
feature of the material is that, when cut to obtain the holes, it
provides accurate smooth edges of the hole.
[0016] The distribution pipe is preferably made of plastic
material, such as polyolefin blend comprising polypropylene or
polyethylene, about 0.2 to 2 mm thick. The plastic material is
stabilized for long-term solar heating and UV protection. The
reflectivity and opaqueness to light in the visible, UV and IR
range are achieved by suitable additives, such as dispersed silver
micro-particles. The plastic pipe wall may comprise an outer
reflective layer and an inner opaque layer.
[0017] The distribution pipe may be manufactured with markings
indicating places where the holes are to be made. The markings may
comprise recesses providing stable positioning of a cutting tool,
by which the holes are to be made.
[0018] In an alternative embodiment, the distribution pipe may be
manufactured with prefabricated holes for connecting the branch
tubes. In such case, the holes may be equipped with annular rims
made of rigid material, with thread or with bayonet locks for
assembling to the connectors in the field. The annular rims may
have an integral cover adapted for easy removal in the field, e.g.
a notch around the rim.
[0019] In yet another embodiment, the distribution pipe further
comprises an internal filter membrane extending along the whole
length of the pipe and dividing its cross-section into two
chambers. The internal membrane filters the irrigation water
passing between the two chambers.
[0020] According to a third aspect of the present invention, a kit
is provided for assembling an irrigation system in the field,
comprising:
[0021] a distribution pipe made of thin-walled collapsible sleeve
with holes, or adapted for cutting therein holes, when filled with
water,
[0022] a plurality of connectors, adapted to connect the branch
tubes to the holes cut in said distribution pipe; and
optionally,
[0023] a plurality of branch tubes equipped with low-pressure drip
emitters.
[0024] According to a next aspect of the present invention, there
is provided a hand-held tool for cutting holes in the distribution
tube of the above irrigation system, comprising a tubular cutter
with thin annular cutting edge formed with plurality of teeth, and
a handle. The tool cuts holes by urging the cutter to the
distribution tube which is filled with water, and rotating the
tool. The tool may be powered by means of an electric drive with
accumulator battery.
[0025] According to a still further aspect of the present
invention, there is provided a method for assembly of a
low-pressure drip irrigation system from the components of the
above-described kit, in an irrigation field, the method comprising:
[0026] providing a source of water ensuring about 2 m H.sub.2O
hydraulic head with respect to the field level; [0027] deploying
the distribution pipe in the field and connecting it to the source
of water; [0028] filling the distribution pipe with water; [0029]
assembling one branch tube with one connector; [0030] if necessary,
cutting a hole in the distribution pipe by means of the hand-held
tool; [0031] inserting the connector into the hole of the
distribution pipe thereby attaching the branch tube to the pipe;
and [0032] repeating the three last steps for the next branch
tubes.
[0033] Thus, the present invention presents an irrigation system
combining the economy, controllability and environmental
friendliness of known drip-irrigation systems working at higher
pressure, and the low investment costs of furrow irrigation
systems. The system of the present invention is especially
appealing by its simple method of assembly and the possibility to
use the existing sources of water used in flood irrigation like
artesian wells, surface run-off waters and others. Moreover, the
irrigation system of the present invention can be directly
assembled on existing fields to replace flood and furrow
irrigation, with no additional earth-moving works.
[0034] With the new system any flood furrow irrigation field can be
upgraded for increasing irrigation uniformity from around 60% to
over 80% (the 20-30% difference means saving of water and energy)
in the new system, allowing to benefit from potentially higher and
better yields.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] In order to understand the invention and to see how it may
be carried out in practice, preferred embodiments will now be
described, by way of non-limiting examples only, with reference to
the accompanying drawings, in which:
[0036] FIG. 1 is a schematic plan of the low-pressure drip
irrigation system of the present invention.
[0037] FIG. 2 is a schematic side view of the drip irrigation
system of FIG. 1.
[0038] FIG. 3A is a cross-sectional view of the distribution pipe
filled with water, with fitted connector and branch tube FIG. 3B is
a cross-sectional view of an alternative distribution pipe with
internal filtering membrane.
[0039] FIG. 4 is a perspective view of the connector used in the
irrigation system of FIG. 1.
[0040] FIG. 5 is a cross-sectional elevation of the filtering tank
used in the irrigation system of FIG. 1.
[0041] FIG. 6 is a perspective view, assembled and exploded, of a
hand punch for cutting holes in the distribution pipe of FIG.
3A.
[0042] FIG. 7 is a series of sectional views of the distribution
pipe of the present invention illustrating the process of cutting a
hole and assembling a connector.
[0043] FIG. 8 is a sectional elevation of an alternative connector
with threaded collar.
[0044] FIG. 9 is an axial sectional view of a hole in the
distribution pipe, equipped with a rigid annular rim.
[0045] FIG. 10 is a perspective view of a rim with a suitable
connector, for alternative use in the distribution pipe shown in
FIG. 9.
DETAILED DESCRIPTION OF THE INVENTION
[0046] With reference to FIGS. 1 and 2, there is shown a
low-pressure drip irrigation system 10, comprising a source of
irrigation water 12, gravitation filter tank 14, outlet pipes 16,
distribution pipes 20, connectors 21, branch tubes 22, and control
system 24.
[0047] The source of irrigation water 12 in FIG. 1 is an artesian
well 26 with a pump 28 and an electric drive 30, but may be any
other suitable source. It is connected to the filter tank 14 which
will be described in detail below. The filter tank 14 is connected
to the pipes 20 by means of the outlet pipes 16.
[0048] With reference also to FIG. 3A, the distribution pipe 20 has
a plurality of holes 40 with edges 41 which are tightly fixed to
base parts 42 of the connectors 21. The pipes 20 are used in
generally horizontal state, while the branch tubes 22 may be
slightly inclined, so as to maintain approximately uniform head in
all drip emitters.
[0049] The distribution pipe 20 is made of thin-walled plastic
collapsible sleeve designed to operate normally under hydraulic
head H not exceeding 3 m H.sub.2O and to withstand accidental
pressures up to about 6 m H.sub.2O. Typically, the distribution
pipe 20 has diameter between 75 and 500 mm when full of water,
while the wall thickness of the collapsible sleeve is between 0.2
and 2 mm.
[0050] The plastic materials used for manufacturing of the sleeve
of the distribution pipe are polyolefin blends stabilized for
long-term solar heat and UV protection, comprising for example,
polypropylene or polyethylene. The plastic material is largely
opaque to most of the light in the visible, UV and IR range and has
good reflectivity. The reflectivity is provided by using color
additives, such as dispersed silver micro-particles. Also, the
sleeve material may comprise an external light-colored reflective
layer and an internal dark opaque layer.
[0051] The material of which the thin-walled sleeve of the
distribution pipe 20 is made is further capable of elastic
expansion so as to allow penetration of the connector 21 when the
latter is manually urged into the hole 40. The necessary elastic
expansion is about 1.6 times the initial diameter of the hole 40
which is provided by elastic (Young) modulus of the sleeve material
about 0.9-1.2 N/mm.sup.2. However, the material should not be
over-extendable, in order to hold the connectors at accidental
deviations of the internal pressure. For example, a suitable pipe
of 10 inch diameter, 0.8 mm wall thickness would hold connectors
with neck diameter 18 mm at least up to pressure of 6 m
H.sub.2O.
[0052] The sleeve material endures overriding by wheeled vehicles
with rubber tires when collapsed empty on sand, clay, mud or other
non-rocky soil. It was found that a suitable sleeve material
allowing about 250% elastic and 500% plastic elongation before
breaking would serve for more than one season of irrigation.
Furthermore, the material of the sleeve allows mechanical cutting
of the holes 40 and obtaining accurate smooth edges 41 particularly
when cut in the field, with the wall of the pipe 20 supported only
by the water in the pipe.
[0053] With reference to FIG. 4, the connector 21 has an axial bore
43, a base part 42, a nipple part 44, and a locking ring 46. The
base part 42 comprises a frustum section 48 starting with an
annular edge 49 at a front end of the axial bore 43 and smoothly
flaring into a first collar 50, a neck section 52 behind the first
collar 50, and a second collar section 54 behind the neck section
52.
[0054] The frustum part 48 is formed so as to expand gradually the
edge 41 of the hole 40 when the connector 21 is urged by hand in to
the hole (see also FIGS. 7e-h). The neck section 52 is narrower
than the first collar 50, whereby it can accommodate the edge 41,
when the frustum part 48 is inside the distribution pipe. The neck
52 is however wider than the hole 40 in non-expanded state and
provides a tight fit to the edge 41. The second collar 54 is wider
than the first collar 50 so as to prevent further penetration of
the connector 21 into the distribution pipe 20.
[0055] The diameter D of the bore 43 is most often between 10 and
45 mm. The hole 40 and the elements of the connector are then
preferably sized as follows: the hole 40 has diameter between 0.8
and 1.0D, the first collar 50 has diameter between 1.4 and 1.7D,
the neck 52 has diameter between 1.1 and 1.3D, and the second
collar 54 has diameter greater than 1.9D.
[0056] The nipple part 44 is formed with a few steps 56 and slight
flare towards the rear end of the bore 43 so as to hold tightly an
inlet end of the branching tube 22 when forced over the nipple
part.
[0057] The locking ring 46 has diameter D2 allowing passage over
the widest step of the nipple part 44 but not allowing passage with
the tube 22 on the nipple. Before assembling the tube 22 to the
connector 21, the ring 46 is placed on the nipple part 44 close to
the second collar 54. After the tube 22 is urged over the nipple
part 44, the locking ring 46 is moved back to the rear end of the
bore where, due to the flare of the nipple, it locks on the tube 22
and secures it to the nipple.
[0058] The branch tubes 22 are equipped with drip emitters 58
capable to work at low pressure, for example NETAFIM emitters
"HyperTyphoon" or "Turbonet".
[0059] The branch tubes 22 are prefabricated in pieces of suitable
length, possibly with connectors 21 pre-assembled at one end of the
piece. The connectors may be bonded, welded or even integral with
the tube.
[0060] With reference to FIGS. 5 and 2, the gravity filter tank 14
is raised on a support with adjustable height, within a range of
1-2 m. The tank is of the type Self Cleaning Gravity Screen
Filtration System, manufactured by Fresno Valves & Castings,
Inc., USA. The filter tank 14 comprises an inlet tank 62 with an
inlet 64 connected to the source of water 12 (FIG. 1), a catch tank
66 connected to the outlet pipe 16, a filtering screen 68 with
rotating jets 69 above the catch tank, and a trash tank 70 with
discharge valve 72. The pump 28 feeds contaminated water from the
source 12 to the inlet tank 62. The water falls on the filtering
screen 68 which retains the contaminants 74 while filtered water 76
passes into the catch tank 66. Contaminants are forced to move
towards the trash tank 70 by the horizontal flow of water over the
screen, and by the rotating jets 69 that spray water through the
screen from below. Contaminants accumulate in the trash tank 70
where they are periodically removed through the discharge valve 72.
Clean water is directed through the piping 16 to the upstream end
of the distribution pipe 20.
[0061] With reference to FIGS. 1, 2 and 5, the control system 24 of
the irrigation system comprises an automated control block 74,
pressure sensors (head indicators) 76 and 78, tank water level
meter 79, pump control block 82, and communication lines. The
pressure sensor 76 measures hydraulic head H.sub.2 at the distal
end of the branch tube 22, while the sensor 78 measures head H1 in
the distribution pipe 20. The head H.sub.2 is usually the lowest
pressure in the irrigation system 10, due to all hydraulic losses
along the water flowpath and especially along the branch tubes
22.
[0062] The control system 24, as known in the practice of
irrigation, is adapted to maintain a predetermined total operating
head H in the system, which means a predetermined level of water in
the catch tank 66, by operating the pump 30 in dependence of the
readings of water level meter 79. In the low-pressure irrigation
system of the present invention, the control system also maintains
the minimal head H.sub.2 in predetermined limits by regulating the
water level in the catch tank 66. That is, the total operating head
H is raised or lowered in dependence of the readings of the
pressure sensor 76 at the distal end of the branching tube 22.
[0063] The low-pressure irrigation system of the present invention
will be better understood and its advantages will be made clearer
if we describe a method of its assembly and a special tool used
with the method.
[0064] With reference to FIG. 6, an example is provided of a
hand-held punch 80 for cutting holes in the distribution tube 20.
The punch 80 comprises a tubular cutter 82 with thin annular
cutting edge 84 formed with plurality of teeth, a handle 86, and a
plunger 88. The handle 86 has a through axial bore 90 communicating
with the inside of the tubular cutter 82. The handle 86 is firmly
fixed to the tubular cutter 82 by a threaded sleeve 92. The plunger
88 is connected to a tail rod 94. The plunger 88 is movably
accommodated inside the tubular cutter, with the tail rod obtained
through the axial bore 90 and protruding out of the handle 86.
[0065] In order to cut the holes 40 (see also FIG. 3A), the
distribution pipe 20 is first filled with water to assume more or
less stable form of a round cylinder. The punch 80 is slightly
urged to the pipe 20 with the cutting edge 84 at the place of the
desired hole. Then the punch 80 is rotated by hand to cut a portion
of the pipe wall and to obtain the hole 40. The cut-out portions of
material from the pipe wall accumulate in the tubular cutter 82,
and can be expelled therefrom by pressing said tail rod 94 and
moving the plunger 88.
[0066] The punch 80 is a uniquely specialized tool with a major
role in the overall efficiency of the assembly process of the
irrigation system of the present invention. Its uniqueness is in
the fact that the cutting edge 84 is so sharp and thin (though
strong enough) that the punch 80 is able to cut holes with very
light pressure on the material of the pipe wall which is supported
from inside by the water pressure which does not exceed 3 m
H.sub.2O in the moment of cutting. Thus, the punch 80 allows the
holes 40 to be cut by hand, in a collapsible pipe that has no
rigidity of its own and which is deployed in the field.
[0067] It will be understood that the punch tool 80 may be designed
and manufactured with powered drive for rotation, for example
electric with accumulator battery, pneumatic and so on.
[0068] The components of the irrigation system described above may
constitute a kit comprising at least two of the following
components: the distribution pipe 20, the branch tubes 22 equipped
with low-pressure drip emitters, the connectors 21 and the
hand-held punch 80 provided for cutting the holes in the
distribution pipe.
[0069] With reference to FIGS. 2, 3A and 7, the method for assembly
of the low-pressure drip irrigation system from the components of
the kit comprises: [0070] deploying the distribution pipe 20 in the
field and connecting it to a source of water ensuring 2-3 m
H.sub.2O hydraulic head with respect to the field level, for
example the filter tank 14 of FIG. 2; [0071] filling the
distribution pipe 20 with water; [0072] assembling one of the
branch tubes 22 with the nipple part 42 of the connector 21, as
described above; [0073] cutting a hole 40 in the distribution pipe
20 by means of the hand-held punch 80; [0074] inserting the
connector 21 into the hole 40, thereby attaching the branch tube 22
to the pipe 20; and [0075] repeating the last three steps for the
rest branch tubes.
[0076] It should be understood that in the time interval between
cutting the hole 40 and inserting the connector 21 into the hole,
the water is flowing through the hole 40 as a free jet. However,
due to the low working pressure, the spilled quantity of water is
insignificant, and the jet cannot prevent the manual insertion of
the connector, nor the connector may be forced out after the
insertion. Also, the above steps may be performed in a different
order, for example the branch tube 22 may be assembled to the
nipple part of the connector 21 after the latter is inserted into
the hole 40.
[0077] The assembly of the branching tubes to the distribution pipe
may be provided in other alternative ways. With reference to FIG.
8, there is shown a connector 110 comprising a body 112 with a
first collar 114, a separate second collar 115 and a sealing ring
116. The connector body 112 is formed with external thread 118
matching respective internal thread in the collar 115. Thus, the
second collar 115 can seal the edge of the hole 40 against the
first collar 114 by tightening up the thread 118.
[0078] The distribution pipe may be prefabricated with holes
punched therein or with holes marked thereon. The holes may be
disposed at predetermined intervals along the distribution pipe
where the intervals may be defined in terms of practical range of
distances between crop rows in the field or just in meters
(feet).
[0079] With reference to FIG. 9, there is shown the wall of a
distribution pipe 120 with a prefabricated hole, which is equipped
with an annular rim 122 made of rigid material and having an axis
A. The rim has an inner portion 123 axially protruding into the
pipe's interior, an outer portion 125 protruding outwardly from the
pipe, and an intermediate portion 127 therebetween the axial
extension of which corresponds to the thickness of the pipe. The
outer portion 125 has an axial extension shorter than total axial
extension of the inner and intermediate portions 123 and 127, and
the inner portion 123 of the rim has an axial extension shorter
than the total axial extension of the intermediate and outer
portions 127 and 125. The rim 122 has a threaded portion 124 for
assembling to a connector in the field. As shown in FIG. 10,
instead of threading, bayonet lock 140 may be used, for assembling
to a connector 142, in which case base part 144 of the connector is
formed accordingly.
[0080] The annular rims 122 have an integral cover 126 preventing
water flow through the hole before assembly. The integral cover 126
is surrounded by a tearable peripheral notch 128 for easy removal.
A simple tool may be used to cut along the notch 128. The recess
130 provides support for a rotating tool tip.
[0081] The rims 122 are tightly fitting the edges of the holes and
are installed therein before deploying the irrigation system in the
field, e.g. fitted in the process of pipe extrusion. The rims are
sufficiently thin so as to allow rolling the collapsed pipe into a
tight reel.
[0082] With reference to FIG. 3B, the distribution pipe 20A may be
provided with an internal filtering membrane 32 extending along the
whole length of the pipe. The pipe cross-section is thus divided
into a supply chamber 34 and exit chamber 36. The internal membrane
32 is made of micro-holed polyethylene sheet or of non-woven
material. The whole pipe is assembled by welding along seams 33 by
bead or heat welding. In operation, muddy irrigation water is fed
into the supply chamber 34, then passes gradually through the
internal membrane 32 along the whole length of the pipe 20A, enters
into the exit chamber 36 and then into the connectors 21. Mud
particles are retained by the membrane and can settle as silt 38 in
the lower part of the pipe due to the low flow velocity. Since the
distribution pipe is several hundred meters long, the filtering
area is huge and the pipe normally does not need flushing
throughout the irrigation season. At the end of the season, the
pipe 20A can be flushed by feeding water in reverse direction (into
the exit chamber 36) and opening the distal end of the supply
chamber 34.
[0083] Although a description of specific embodiments has been
presented, it is contemplated that various changes could be made
without deviating from the scope of the present invention as
defined in the following Claims.
* * * * *