Note: Descriptions are shown in the official language in which they were submitted.
~03~9
BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates to low drift spray nozzles and, more partic-
ularly, to spray nozzles and methods of spraying in which th~ liquid spray
comprises large droplets.
In numerous applications it is important that liquid which is to be ~ -
handled is discharged in a manner and in a condition in which drift is
minimized. By way of example, one such application in which drift must
be minimized is in the application of conventional herbicides, pesticides
and other farm chemicals. Another such application in which drift is
critical is in present day irrigation type rigs in which partially treated
sewage is applied to the large tracts of land. Potential problems involved
in the application of such sewage are not only limited to odor, but also ~ `
viruses in the sewage might be carried by small droplets to adjacent
localities if drift is not stringently controlled. To underscore the problems ,
in such sewage applications, Federal as well as local agencies have ;
arbitrarily set limits on the amount of drift which is permissible in such
sewage irrigation installations. Under these limits, drift is generally -
confined to within ~00-300 feet of the point of application and droplets ` ?
which drift beyond this range are not acceptable.
In order to remain within these acceptable drift standards, irrigation
sewage disposal equipment in the past have employed flooding or deflector
type nozzles which are generally operated at very low pressures, frequently
as low as 3 or 4 psig. At these low pressures, the generation of large
droplets results and the generation of fine droplets, which could create a
drift hazard, is minimized. Several important disadvantages, however,
follow from the use of such low pressures. It is frequently difficult to
obtain a good spray pattern with such low pressures and consequently
coverage uniformity is at best minimal. Also, any variation in the s-upply
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pressure or pressure losses in the equipment itself due to frictional
losses or pressure drop inherent in the piping, will cause a change in
flow rate through the nozzles which adversely effects uniformity of
coverage. Such pressure drops or losses are indeed common, as will
be evident when it is considered that irrigation equipment i9 frequently
in excess of 1000 feet in length and this lequipment normally rotates
about a pivot point with the extremities of the irrigation rigging often
crossing terrain that is not completely level, causing pressure variations
due to ground elevation. These variations due to ground elevation may
be as great as 3 to 5 psig.
The nozzles and methods of the present invention overcome these
disadvantages. In a nozzle and method incorporating the principles of
the present invention, liquid pressures greatly in excess of those pre-
viously mentioned, may be utilized and yet the generation of large drop-
lets which are not subject to drift may be optimized. Accord~ngly, since
the method and nozzles of the present invention are capable of utilizing
substantially larger line pressures, the adverse effect of changes in -~
elevation, frictional losses and the like are minimized. In the nozzles and
method of the present invention, line pressures may be employed, which
if employed with the conventional no7zles heretofore utilized in the art,
would produce extremely fine droplets which would drift substantial distances.
Moreover, the noz~les and method of the pxesent invention are capable of
delivering liquid at widely ranging flow rates of more than 50 gpm to as
little as . 2 gpm without a substantial loss in droplet quality. Finally,
nozzles and method incorporating the principles of the present invention
result in substantially improved patternation definition and uniform
distribution of droplet sizes.
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Accordin~ to the present invention, a nozzle for producing a
- swirling discharge of a hollow geometric shape having substantially large
droplets therein comprises a first chamber having a fluid inlet for introduc-
ing fluid to said first chc~mber, swirl means for imparting a swirling motion ~:
to the fluid in said first chamber, a second chamber, first orifice means
between said first and second chambers, said swirling fluid passing from
said first chamber to said second chamber through said first orifice means,
said second chamber being larger in cross section than said first orifice :
means, and means for discharging the swirling fluid from said second chamber
while still in its swirling condition to form said swirling discharge of .
said hollow geometric shape and having said substantially large liquid `~
droplets therein, said means for discharging including second orifice means
at an end of said second chamber opposite said first orifice means, said
second orifice means being at least as large in cross section as said first
orifice means.
According to the present invention, a method of producing large : :.
. droplets of liquids comprises imparting a swirling motion to the liquid, .
passing said swirling liquid through first orifice means into a chamber ~`
larger in cross section than said first orifice means and such that the ~-
liquid continues to swirl in the chamber, and producing a swirling discharge
having a plurality of substantiall~ large droplets of liquid therein by
discharging the swirling liquid from said chamber through a second orifice
at least as large in cross section as the first orifice means~
Other features and advantages of the present invention will be more
clearly understood through a consideration of the followlng detailed descrip~
tion.
In the course of this description, reference will frequentl~ be
made to the attached drawings in which: ~
Figure 1 is an exploded isometric view of a preferred embodiment ; ' 7
of nozzle incorporating the principles of the present lnvention and which
employs the method of the present invention;
Figure 2 is a cross sectioned elevation view of the assembled
nozzle shown in Figure 1 showing the fluid flow path of the ~luid;
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FIG. 3 is an exploded isometric view of another pre~erred embodiment
of nozzle incorporating the principles of the present invention and which
employs the method of the present invention;
FIG. 4 is a cross sectioned ele~ration view of the assembled nozzle
shown in FIG. 3 showing the fluid flow through the noz~sle;
FIG. 5 is a cross sectioned elevation view of still another preferred
embodiment of nozzle constructed in accordance with the principles of
the invention and which employs the method of the present invention and -; .
which shows the fluid flow path through the nozæle;
FIGS. 6A-6D are patternation plots showing the radial patternation
of the nozzle and method of the present invention as compared to radial ,`.~ ~:
- patternation of three conventional nozzles; and ` ~ -
FIGS. 7A-7D are patternation plots showing l'band" patternations of ~ .
the nozzle and method of the present invention as compared to such
patternation of three conventional nozzles. ;
DESCRIPTION OF THE PREFERRED EMBODIMENTS .
Referring particularly to FIGS. 1 and 2, a first preferred embodiment
of nozzle is shown which is constructed in accordance with the principles of
..
the present invention and which practices the method of the invention. The ~ ~-
nozzle comprises a nozzle tip member 10 having a large passage 12, a
passage of slightly decreased diameter 13, a passage 14 of still further
decreased diameter aligned with each other along a common axis, the
smaIler passage 14 defining a vortex chamber 16. The vortex chamber 16 ~
is chamfered at its end 18 opposite passage 13 and this chamfered surface ~ -
leads to a circular discharge orifice 20 which opens through the end 22
of the tip member 10.
A cup-shaped orifice disc 24, having an annular flange 26 extending
peripherially therefrom, is inserted into the passage 12 until the forward
face 28 of the flange 26 comes into contact with and is supported on an
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annular shoulder 30 formed of the junction of passages 12 and 13. I'he
disc 24 is generally concave shap~d having a flat bottom 32. As will be
understood in the description of operation to follow of the present embodiment
of nozzle, the hollowed out concave portion of the disc defines a swirl
chamber 34 containing swirling liquid during operation of the nozzle. A
circular "primary" orifice 36 is formed in the flat base or bottom 32 of
the disc 24 and communicates the swirlillg liquid in chamber 34 with the
vortex charnber 16 as shown in FIG. 2.
Again referring to FIGS. 1 and 2, a circular core disc 38 is next
positioned in passage 12. The core disc 38 comprises an annular raised
rib 40, the outer perimeter of which is preferably chamfered at 42. - ~;
The raised rib 40 and its chamfered surface 42 are adapted to fit into and
- contact the interior of the orifice disc 24 as shown in FIG. 2, One or more
angled liquid inlet passages 44 extend through core disc 38 in a substantial
angled relationship to the central axis of the nozzle.
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Finally, the discs 24 and 38 are firmly held in place by a threaded
nozzle body 46 which is threaded into passage 12 at 48 and into contact
with the 2ear side of the core disc 38. The nozzle body 46 indludes a .
fluid passage 50 and is threaded at its other end 52 for receipt of a suitable
hose or conduit from a source of liquid (not shown) which liquid is to be
discharged through the nozzle.
An important feature of the present invention resides in the size
relationship of the orifices 20 and 36 and the vortex chamber 16. It has
been found that to generate a spray having the desired large droplet si~e,
the vortex chamber 16 must have a diameter or cross sectional area which
is substantially larger than that of either of the orifices 20 or 36. More-
over, it is important that the discharge orifice 20 be at least as large in
cross section, if not larger than, the primary orifice 36. ',
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Although it is not fully understood at this time exactly what the
nature of thc action is which occurs in the vortex chamber 16 which
results in the large droplet size in the ~inal noz~le discharge, it is believed
that a certain amount of air is entrained in the relatively lower pressure
swirling liquid in the vortex chamber 16. This air is supplied through the
core A o~ the liquid which is being discharged through the discharge -, ~
orifice 20 as show-n in FIG. 2. During passage through the vortex chamber ` ~ -
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16, the liquid droplets appear to agglomerate in the vortex chamber such
that the spray which i9 discharged through the discharge orifice forms a
well defin~d swirling hollow cone B (in the case of a circular orifice 20
as shown) which is filled with large droplets C of liquid. It is believed
that the passage of at least some air through the core ~ of the discharge is
important to achieve the results of the present invention, since when the
size of the discharge orifice is reduced to a size smaller than the primary
orifice such that the core A is substantially reduced in size, the result
is a fine mist such as that normally produced by a conventional nozzle.
In operation, liquid is introduced through nozzle body 46 and '~
angled passages 44 in the core disc 38 into the swirl chamber 34 defined
between the disc 38 and the orifice disc 24. Swirl is imparted to this
liquid in this chamber 34 due to the angularity of the passages 44~ This
swirling liquid is then discharged through the primary orifice 36 into the
vortex chamber 16 where it continues to swirl, but expands against the
walls 14 of the chamber, as shown in FIG. 2. Finally, this swirling ~
liquid is discharged through the discharge orifice 20 in the form of a ~ ~ -
hollow cone B in the case of a circular orifice as is shown. The liquid
in the discharge cone B comprises a plurality of substantially large drop~
lets C of a size which reduces the likelihood of drift.
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A second preferred embodiment of no~zle is shown in FIGS. 3 and 4.
In this embodiment of nozzle, a body 54 includes a bore 56 which i9
threaded internally at 58. An angular liquid inlet passage 60 extends
between the bottom of the bore 56 and another bore 62, the latter of which
is also threaded at 64 to receive a suitable liquid supply conduit (not shown).
A tip member 66, comprising an enlarged passage 68, a smaller
diameter passage 69 and a flared primary orifice 70 is threaded, via
: threads 72, into the threads 58 in bore 56 as shown in FIG. 4. When
fully threaded into the bore 56, the left end 74 of the tip member 66 is
spaced from the bottom of the bore 56 by engagement of the chamfered ;
surEaces 75 to define a swirl chamber 76 into which the angular liquid
inlet passage 60 discharges in substantially tangential relationship to the
chamber 76.
.
The interior of passage 68 is also threaded over a part of its length .
at 78 and a second tip member 80 i9 threaded, via threads 8Z, into the
. - ,
threads 78 in passage 68 as shown in E`IG. 4, until an enlarged shoulder
84 comes to rest against the edge 86 of member 66. A discharge orifice
88, preferably chamfered as shown at 90, is located in the end of the t ip
80~and a passage 92 through tip member 80 defines a vortex passage 94
into which the swirling liquid is discharged from the chamber 76 through
the primary orifice 70. As in the embodiment shown in FIGS. 1 and 2,
the cross sectional dimension of the vortex chamber 94 is larger than the . `diameter of orifice 70 and its passage 69 and the discharge orifice 88 is as
large if not larger than orifice 70 and passage 69.
The operation of the noz~le shown in FIGS. 3 and 4 is substantially
identical to that previously described. Liquid is introduced through bore :
6Z and the angular inlet passage 60 into swirl chamber 76 where s-wirl is
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lQ37~
- imparted to the liquid by way of the angular passage. This swirling liquid -
then passes through the orifice 70 and expands, still swirling, into the
vortex chamber 94. From the vortex chamber 94 the liquid is discharged `
through the discharge orifice 88 in the form of a swirling hollow cone B
consisting of large droplets C.
Still another embodiment of nozzle is shown in FIG. 5 in which an
insert member 100 is provided to form the prirrlary orifice disc and vortex
chamber. Referring to FIG. 5, a nozzle body 102 includes a bored recess
104 in one end thereof. An angular or tangenti~al liquid inlet passage 106
extends into the base of this bore and the cup shaped insert member 100, `
having an annular ~lange 108, is positioned in the bore, the flange 108
being supported on the end of the body member 102. The insert member
100 is recessed to define a vortex chamber 110 and the flat bottom 112 of
the insert member includes a circular primary orifice 114 as shown in
FIG. 5. When positioned in the recess 104, bottom 112 of the insert
member 100 is spaced from the bottom of the recess to define a swirl
chamber 116 into which the angular inlet passage 106 communicates. A
tip member 118 including a chamfered surface 120 terminating in a
circular discharge orifice 122 is threaded onto the body member lOZ at 124
and holds the insert member 100 in the recess 104.
In this embodiment, a strainer 126is shown positioned over the
body member 102 to remove solid contaminants which might otherwise
foul the nozzle assembly. Finally, the entire assembly is threaded at
128 into the end of a liquid supply conduit 130 shown. Again the relationship
between the sizes of the orifices 114 and 12~ and the cross sectional
dimension of the vorte~ chamber 110 is as previously described with respect ~ ,
to the embodiments shown in FIGS. 1 - 4.
The operation of the embodiment shown in FIG. 5 is also substantially
identical to that previously described. The liquid passes through conduit
130, strainer 126 and the angular passage 106 which imparts a swirling
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motion to the liquid in the swirl chan~ber 116. This swirling liquid is
then discharged througl1 the primary o~ilice 114 into the vortex chamber
110 where the swirling liquid expands into contact with the walls of the
vortex chamber. From the vortex chamber 110 the swirling liquid is
discharged through the orifice 122 to form a hollow cone B having large
droplets C o~ the liquid entrained therein.
As previously mentioned, the size relationship of the primary
orifices 36, 70 and 114 and discharge orifices 20, 88 and 122 are important
in the present invention as is the size relationship between the primary ;
orifices and the cross sectional dimension of the vortex chambers 16,
94 and 110. Specifically, the cross sectional area or diameter of the
discharge orifices 20, 88 and 122 should be at least as large, if not larger
than, the cross sectional area or diameter of the primary orifices 36, 70
and 114, respectively. Also, the cross sectional diameter or area of the
vortex chambers 16, 94 and 110 should be s~lbstantially larger than the
cross sectional diameter or area of the primary orifices 36, 70 and 114,
respectively. The length of the vortex chambers may be varied over wide
ranges without substantial alteration of the droplet quality. -
It has been found that the nozzles of the present invention provide a
final spray cone having a droplet size and patternation which is substantially ,~
improved over a prior conventional nozzle operating at the same or less
pressure and flow rate. For example, a nozzle constructed as shown in
FIGS. 3 and 4 was operated at a line pressure of 40 psig with water as the
liquid both with the tip member 80 removed to act as a conventional nozzle,
and with the tip member inserted to practice the method of the present -~
invention. In this nozzle, the minimum diameter of the primary orifice 70 -
at passage 69 was 0. 531 inch and the discharge orifice 88 was 0. 8 inch in
diameter. In addition, another nozzle constructed as shown in FIGS. 3
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~037~9
and 4 was like~,vise operated under the same conditions with the tip 80
inserted and with the tip rer~oved. This nozzle was the same as the
previous nozzle, except that the primary orifice 88 in the last mentioned
nozzle was reduced to 0. 33 inch in diameter. It was found that the flow
rate in both of these nozzles remained substantially unchanged when the
tip member 80 was inserted or removed. Moreover, the droplet size in
the discharge of the nozzle with the tip member inserted was visibly sub-
stantially larger than that in the spray cone of the nozzle where the tip
member was removed. ~
In addition, tests were run on a nozzle constructed as shown in ~ ~;
FIGS. 1 and 2. In this nozzle the core disc 38 was constructed of plastic.
- Again these tests were conducted utilizing water as a liquid at 40 psig line
pressure. In these nozzles, the discharge orifice 20 was held constant in
size at 0.125 inch in diameter and the diameter of the primary orifice 36
was varied between 0. 063 and 0.1250 inch. The diameter of the vortex
chamber 16 in each of these nozzles was 0. 20 inch. It was found that such
nozzles wherein the ratio of the diameter of the discharge orifice Z0 to~the
diameter of the primary orifice 36 was less than 1. 33 produced a spray
which was too fine such as would result in substantial drift in use.
Patternation tests were also conducted on nozzles constructed as shown in
FIGS. 1 and 2 and as last described. Details of the patternation equipment ~
and methods will not be set forth herein. For a general description of ~ -
such equipment and methods as employed in radial patternatioD tests,
reference should be had to Tate. R. W., Spra~,r Patternation, Industrial &
Engineering Chemistry, Vol. 52, p. 49~, Oct. 1960. The patternation
tests included radial patternation tests in which the test nozzles were fixed
four inches above the patternation tubes and the liquid consisted of water.
The results of these tests are shown in FIGS. 6A-6D in which the units
-10-
~L~37~9~ ~
along the x-axis represent units oE distance radially ~rom the centerline
C/L and the y-axis represent units of volume of liquid collected.
In FIGS. 6A, the test results are shown for a no~æle collstructed
as shown in FIGS I and 2 in ~,vhich the tip merrlber 10 was inserted as
shown in FIG. Z. In this nozzle, the diameter of the primary orifice 36
was 0.063 inch, the diameter of the vortex chamber was 0. 2 inch, and
the diameter of the discharge passage was 0. 125 inch.
In the remaining three FIGS. 6B-6D, radial patternation results are
shown for three nozzles exactly the same as shown in FIGS. 1 and 2, but
10 in which the tip member 10 was removed and the discs 24 and 38 retained
to form conventional noz~les. These tests were conducted using the same
liquid as that previously described. In the test shown in FIG. 6B, the
size of the orifice 36 was the same as the nozzle of the invention shown in
FIG. 6A, 0.063 inch, and the pressure of the water was also the same,
40 psig. The flow rate through the nozzles tested in FIGS. 6A and 6B
was substantially identical, O. Z6 gpm and 0. 29 gpm, respectively.
In the test shown in FIG. 6C, the diameter of primary orifice 36
was enlarged to . 078 inch) and to achieve the same 0. 29 gpm flow rate,
the pressure was reduced to 13 psig.
In the test shown in FIG. 6D, the diameter of the primary orifice 36 `
was further increased to 0. 094 inch, and to maintain the same 0. 29 gpm ` `
flow rate, the pressure was further reduced to 8 psig.
Upon consideration of FIGS. 6A-6D, it will be seen that sharp
patternation definition clearly resulted in the nozzle of the present invention,
i. e. that shown in FIG. 6A. In addition, discharge cone width of the
nozzle of the present invention was superior. On the other hand, pattern-
ation was not as well defined in the remaining FIGS. 6B-6D as is shown
by the presence of some liquid in what should be hollow center C/L oE the
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cone and in the blurred "tailing off" at the periphery of the cone, i. e. at
lO and ll units of distance away from the centerline. Moreover, the cone
width of the conventional nozzles was generally less than the discharge
cone of the invention no~zle.
Referring to FIGS. 7A-7D, the results of the "band" patternation tests
are shown for the same nozzles, the same liquid and same pressures as
described with respect to FIGS. 6A-6D, respectively. These tests are
substantially identical to those shown in FIGS. 6A-6D, except that the
- test nozzles are ~nounted over a receiver having a plurality of longitudinally `
extending troughs extending in parallel to each other. The test nozzles
were again set at Eour inches above the troughs.
As would be expected from the results shown in FIGS. 6A-6D, the
patternation definition and discharge cone width of the nozzle of the
present invention as shown in FIG. 7A was substantially superior to those
of the conventional nozzles shown in FIGS. 7B-7D.
The droplet size produced by the nozzles as last described was also
measured, again using water at a pressure of 40 psig. In the nozzle of
the invention as described with respect to FIGS. 6A and 7A, the "Sauter
mean" droplet diameter was measured at 362 microns with a maximum
diameter of 787 microns, resulting in a ratio of maximum to mean
diameter of slightly larger than 2 which is exceptionally good. For the
same nozzle with the tip member lO removed, as described with respect
to FIGS. 6B and 7B, the "Sauter mean" droplet diameter was measured
at 144 microns and the maximum diameter was 406 microns. Moreover, `~
the total percentage of spray volurne of droplets less than 42 microns in
diameter was l. 93% in the latter nozzle and only 0. 22~o in the nozzle of
the invention with the tip member lO inserted. Thus, the uniformity of the
spray of the same identical nozzle in which the tip member lO, i. e. the
vortex chamber 16 and discharge orifice 20, were removed, was about
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~V3~99'3
twice as poor as the nozzle of the invention, the maximum and mean
diameters were substantially smaller, and the quality of small droplets
was substantially larger.
When the primary orifice 36 was increased in diameter to 0. 078
inch, without the tip Inember 10, as described with respect to FIGS. 6C
and 7C, and the liquid pressure was dropped to 13 psig to attain the same
flow rate, the "Sauter mean" diameter increased to 217 microns and the
percentage of droplets less than 42 microns decreased to 0. 85%. Thus
even at a lower pressure, this conventional nozzle did not produce mean
droplet sizes as good as those of the nozzle of the present invention nor
did it reduce the quantity of small droplets to the quantity realized by the
invention no~szle.
It has also been found that the nozzles constructed in accordance
with the present invention and the method thereof may be readily employed
in nozzles of the "bypass" or "spill" type in which liquid is bled off the
rear of the swirl chamber and returned to the source. Moreover, although
the discharge orifices 20, 88 and 122 have been described in terms of a
circular orifice, it is contemplated that other shapes of orifices, e. g.
elliptical or slot shaped orifices, may be employed in the present invention
if it is desired to obtain discharge shapes in the shape of a fan or other
desired shape without departing from the principles of the present invention. -
It will also be understood that although the principal application of
the nozzles and method of the present invention have been described in -
terms of agricultural applications,the invention is not intended to be
limited to uch applications,but may be employed in any end use in which
droplet size, definition or uniformity is important.
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Finally, it will be understood that the embodiments of the present
invention which have been described are merely illustrative of a few of
the applications of the principles of the invention. Nu~nerous modifications ,
; - may be made by those skilled in the art without departing from the true spirit and scope ot the invention.
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