Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
2 e.
DELIVERY APPARATUS FOR THIN INVERT EMULSIONS
Background of the Invention
1. Field of the Invention
This invention relates to the field of delivery systems for
chemical agents such as herbicides, pesticides, fungicides and the
like, and in particular to a delivery system adapted to deliver
thin solutions in the form of uniform small droplets, for example
thin oil/water inverts having an oil based su~face on a water based
droplet.
2. Prior ~rt
In applyiny herbicides, pest:icides, fungicides and similar
agents to an area to be treated, it is highly desirable to apply
only the minimum amount of the agent necessary to achieve the
desired effect, and to apply the agent only to the area being
treated. Insofar as the agent is applied in a form that is not
readily absorbed, or insofar as the agent drifts away from the
; target site or evaporates before it is absorbed, the agent is not
only wasted, but is a form of pollution.
Two types of carriers for active agents applied in
agricultural situations and the like are oil soluble ones and water
soluble ones. For the most part, the active ingredients used in
the oil soluble and water soluble formulations are the same.
Esters are examples of oil soluble carriers and the amines are
examples of water soluble ones.
Esters are volatile. Even after reaching the vegetation or
the like to be treated, the ester can volatilize before the active
ingredient is absorbed. Similarly, amines are subject to
evaporation. As an amine is delivered, a proportion of the water
evaporates and is lost into the air. Both water soluble and oil
soluble products should be delivered in a form that will min~mize
the loss of active material and the escape of active material into
the environment, before absorption.
; In spraying equipment for liquid agricultural agents, both the
form of the liquid being applied and the mechanics of application
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of the liquid are important considerations for achieving the
eff~cts desired. In one formulat:ion known as an "invert" an
emulsion of water and oil is provided. The invert is made
relatively viscous by using a viscous oil and/or extensive
agitation (tending to thicken the material), to cause formation of
larger droplets as a means to reduce drifting of the agent from the
site of application. Drift control is then less important because
the larger droplets tend to simply fall onto the site. Generally,
an invert is characterized by -droplets wherein a water soluble
agent is encapsulated in a *ilm of oil as the produc* is applied.
When the product is emitted through a spray nozzle or the like, the
oil forms a film on the water and tends to hold the water in a
droplet rather than to allow the droplet to break up. Whsreas
water and oil are immiscible, the mixture of water and oil tends
to separate after a time. Although the water and oil can be
agitated initially ~when mixing a quantity of material for
application), separation of the water and oil freguently occurs,
for example in spray equipment which is idle for a time.
In a thick invert formulation, the viscosity of the li~uid
makes it difficult or impossible to discharge the li~uid in the
form of small droplets formed by surface tension of the liquid
after discharge from small orifices. As the viscosity of the
discharged liquid is increased, the flow through small orifices is
obstructed and eventually blocked. In addition, the liquid is
discharged in the form of strings rather than droplets, which
strings form into droplets of varying sizes, both small and large.
For these reasons, inverts have not been applied using a nozzle
arrangement wlth small orificas. The liquid was too thick, and
there was no need to use small orifices when the basic objective
of making an invert was to increase viscosity and achieve large
droplet sizes.
It is desirable to control drift by the mechanics of
application of the product rather than by relying on large droplet
size. Larger droplets cover less effectively than uniform small
droplets, for example using an invert with a relatively less
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viscous character due to the concentration or formulation of the
oil phase, and/or due to the extlant of agitation. The better
coverage of small drople~s provides higher efficacy per unit volume
of the agent being applied. However, it is difficult to form and
deliver uniform small droplets in a manner that will not drift
unduly, evaporate during delivery, volatilize after delivery, or
otherwise defeat the purpose of applying a chemical agent in a
manner achieving good coverage and good absorption.
A known boom type aerial agricultural spray device is
disclosed in ~S Patent Application SN 621,355, ~iled December 3,
199~, which is hereby incorporated. A plurali*~ of orifices are
provided on the trailing edge of an airfoil shaped conduit which
is positioned perpendicular to a direction of travel of an
aircraft, for example on the front of the skids of a helicopter or
below the wing of a fixed wing aircraft. The orifices are provided
with nozzles which are wedge shaped along their trailing edge, each
having a diaphragm valve coupled to a port which protrudes in the
form of a fitting at the leading edge of the airfoil. This form
of delivery structure is characterized by substantial disturbance
of the laminar flow of air, interfering with the formation of
uniform droplets. Particularly when used with fixed wing aircraft
(wherein the turbulence generated by the wing further disturbs the
laminar flow), the device emits the liquid in a mix of larger and
smaller droplet subject to drift and waste.
Assuming that a uniform application of small droplets can be
accomplished, the volume of material applied to a site to be
treated can be reduced. With more accurate application, a more
concentrated agent can be applied. Smaller, lighter equipment can
be used to apply the material, and the effectiveness of the agent
is improved. Moreover, when the small droplets can be formed as
an invert with a water phase enclosed in an oil surface layer,
problems with evaporation are reduced. The oil tends to assist in
penetration of the waxy surface of vegetation, and the overall
efficacy of the chemical agent is improved.
Relatively thinner formulations may produce smaller droplets,
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but cause other problems. In an aerial spraying application, for
example, the difference in fluid head between the orifices along
a spray boom or the like can cause thin material to dribble ~rom
the orifices, leading to waste and potential pollution,
particularly if differences in fluid pressure occur across the
length of a boom or similar conduit with orifices for discharging
the liquid. Similarly, when removing and replaclng valves or
nozzles on the boom, thin material in the boom readily leaks out
when the valve or nozzle is removed, polluting the ground.
According to the invention, an apparatus is provided for
application of a thin invert in a manner that produces small
uniform droplets. The problems with separation of the oil and
water portions of the formulation are overcome by a recirculating
system that agitates the material directly in -the spray apparatus.
In connection with aerial spraying, a plurality of wedge shaped
nozzles along an aerodynamically shaped conduit are each provided
with trailing small tubes leading to an internal manifold coupled
to the condui~ at a check valve. A pump coupled between a storage
reservoir and an end of the conduit pressurizes the conduit to open
the check valves and commence application of the product. A second
conduit runs along the conduit and is preferably disposed inside
the conduit. The second conduit is arranged in a recirculation
path adapted to agitate the material in the system to prevent
separation. The second conduit also tends to equalize pressurQ in
the conduit between the end coupled to the pump and the remote end,
leading to application of uniform small droplets. Preferably one
or more pumps is arranged with one or more control valves such that
the system is controllable between a delivery condition in which
the pump pressuri~es the conduit and a recirculating condition
wherein the pump recirculates the material to a storage -tank. By
a suitable arrangement of pumps and/or valves, in the recirculating
condition the conduit can be evacuated. Therefore, if a nozzle or
outlet valve is removed ~rom the conduit in the recirculating
condition, air is drawn in through the opening and the conduit can
be drained, and/or escape of the chemical agent can be prevented.
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Summary of the Invention
It is an object of the invention to provide a means to apply
thin invert preparations in the form of uniform small droplets,
with a minimum of loss of material ~due to drift and dribbling.
It is also an ob~ect of the invention to provide a means for
agitating oil and water preparations in the output portions of a
delivery apparatus, to prevent or reverse separation of the oil and
water.
It is a further object of ths invention to provide a delivery
apparatus for thin oil/water inverts, wherein surface tension of
the liquid is the primary effect that determines droplet size, for
delivery of uniform small droplets. -~
It is a further object of the invention to provide a
recirculation means that can apply a vacuum to a delivery conduit
having orifices, such that escape of material is precluded by
operation of the recirculating means even if an orifice remains
open.
These and other objects are accomplished by a delivery system
for a liquid chemical agent is especially adapted for thin
oil/water inverts, including recirculation means for agitating the
agen~ and a nozzle arrangement wherein uniform droplets are
produced due to surface tension. The system has a reservoir, a
first conduit which is airfoil shaped and has spray nozzles along
its length, co~pled to the first conduit through check valves, and
a pump for moving the agent into the first conduit under pressure.
A second conduit within the first has an inlet communicating with `
the reservoir and an outlet remote from the inlet along the first
conduit. For discharge the agent is pumped into the two conduits
in parallel, pressurizing opening the check valves. For
recirculation and prevention of leakage of the agent, the agent is
pumped out of the first conduit and into the reservoir, thus
closing the check valves and agitating the agent, which flows
serially through the conduits. Should a valve be removed or stuck
open, air is drawn into the conduit in the recirculation mode. The
conduits preferably are coupled to a base fitting having distinct
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couplings for the boom and the tube. The discharge nozzles each
have a tubular housing leading smoothly from the trailing edge of
the boom to a horizontal wedge shaped terminus. A manifold in the
housing leads to capillary sized outlet openings along the
terminus. The check valves are simple spring mounted plungers
opening under pressure of the liquid, and closing with vacuum or
equal pressure.
Whereas the nozzles define aerodynamically smooth structures
at the trailing edge of the boom, and the capillary size tubes
Goupled to the manifolds are subject to substantially equal
discharge pressures along the length of the boom, the primary
parameter affecting formation of droplets is the surface tension
of the liquid agent. By using a thin invert for the liquid agent,
the system applies uniform small droplets.
The capability of agitating the liquid agent by recirculating
the agent in the system prevents separation of the oil and water
phases. Even after a period of inactivity the agent can be
reconstituted by operating the recirculating means. The
recirculating means defines a flow path including the boom,
internal conduit and reservoir, thus ensuring that all portions of
the agent throughout the system can be reconstituted.
Any substantial pressure differential between the capillary
tube outlets is avoided. Inasmuch as the conduit within the boom
l~ads from the pump to a point remote from the inlet to the boom,
the pressure drop normally found along a conduit having successive
outlets is minimized. At each individual nozzle, the capillary
tubes disposed horizontally along the trailing edge of the wedge
shaped nozzle are coupled to the common manifold. Accordingly, the
pressure applied at each tube is e~ual across the nozzle,
minimizing any fluid pressure differential within the nozzle and
preventing siphoning of the contents of the nozzle which would
cause dribbling o~ the agent from the nozzle during banking or
turning of the aircraft.
The invention is particularly effective in connection with a
helicopter mounted liquid application system for application of
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thin inverts. A variety of pump and valve arrangements are
possible in order to operate the system. This variety, and a
number of alternatives for the specifics of the system, are
discussed herein with reference to certain exemplary embodiments
where the invention is illustrated.
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Brief Description of the Drawinqs
There are shown in the dra~ings the embodiments of the
invention as presently preferred. It should be understood that the
inYention is capable of embodiment in a number of specific
arrangements in accordance with the disclosure herein, and
reference should be made to the appended cl~ims rather than the
discussion of exemplary embodiments to better assess the scope of
the invention in which exclusive rights are claimed. In the
drawings,
Fig. 1 is a partial cutaway perspective view of the boom,
internal conduit and one noz~le according to the invention;
Fig. 2 is a partial plan view illustrating an exemplary boom
arrangement, partially cut away to show the internal conduit;
Fig. 3 is an exploded section view through a nozzle, along
line 3-3 in Fig. l;
Fig. 4 is a partially cut away perspective view of a base
fitting according to the invention, for coupling the pump, valve
means and reservoir to the boom and to the internal conduit,
respectively;
Fig. 5 is a schematic illustration of a flow arrangement in
tha discharge moda of the system;
Fig. 6 is a schematic illustration of ~he flow arrangement
according to Fig. 5, in the recirculating mode;
Fig. 7 is a schematic illustration of an alternative flow
arrangement having separate pumps for discharge and recircula~ion.
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Detailed DescriDtion of the Preferred Embodiments
In order to achieve application of thin oil/water inverts in
the form of uniform small droplets, it is necessary to address the
character of the solution, and in particular its viscosity, as well
as the character of the pumps and flow patha defined between an
inlet and an outlet. The inventiorl provides a plurality of small
outlet openings 57, which are capillary sized for the viscosity of
the chemical agent, coupled to a delivery system which includes
means for recirculating the solution in order to reverse separation
of the oil and water phases, by agitation.
With reference to Figs. 1-7, the delivery system for a li~uid
chemical agent includes a reservoir 73 for storage of the agent in
liquid form. The reservoir 73 can be, for example, a tank on an
aircraft or ground vehicle, with sufficient storage capacity to
hold a convenient quantity of solution to be dispensed before
refilling. With known chemical agent delivery systems which are
not structured for drift control or which control drift with thick
oil/water inverts (i.e., using large droplets), a supply of 25 to
50 gallons may be needed to treat an acre of ground. According to
the invention a smaller quantity is needed, because a uniform
application of small droplets of a thin invert or the like is
substantially more efficacious. Two to four gallons of liquid
agent are generally sufficient to treat an acre. Therefore, a tank
on the order of twenty to fifty gallons capacity will normally be
sufficient to hold a convenient amount of liquid agent, and will
not need to be refilled frequently.
A first conduit 31 has a plurality of spray nozzles 42
defining outlet orifices 57. The nozzles and their orifices are
disposed along a length of the first conduit 31 and are in each
case coupled ~o the first conduit through at least one check valve
53. Pump means 64 and/or 65 (see Figs. 5-7) are coupled to tha
first conduit 31 for delivering the agent from the reservoir 73 to
the first conduit 31 under pressure sufficient to open the check
valves 51 and thereby emit the agent through the orifices 57 of the
nozzles 42.
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A second conduit 75 is disposed within the first conduit 31.
The second conduit 75 has an inlet 77 communicating with the
reservoir 73 and an outlet 76 remote from the inlet 77 along the
length of th~ first conduit 31. A valve configuration 83, and/or
a particular pump arrangement are controllable for pumping the
agent from the first conduit 31 at ,a point remote from the outlet
76 of the second conduit 31 to the reservolr 73 in a recirculating
mode of the device. This reverse biases the check valves 51 and
closes the nozzle outlets 57 while recirculating the agent. As a
result the agent is agitated and the oil/water phases are mixed
throughout the system, in~luding the contents of the first and
second conduits.
As shown in Figs. 1, 2 and 5-7, the second conduit 75 can be
disposed directly within the first conduit 75. The first and
second conduits 31, 75 thus define a first passageway 61 between
an outside of the second conduit 75 and an inside of the first
conduit 31, and a second passageway within the second conduit 31.
The nozzle orifices 57 are coupled to the first passageway 61. By
reversing the pump-powered flow it is possible according to the
invention as shown to flush the first conduit 31 in the
recirculating mode. In the regular discharge mode, the pressure
drop which would occur along the first conduit 31 from its inlet
to the most remote of the nozzles is minimized because the second
conduit (which does not have orifices along its length) boosts the
pressure within the first conduit at the area adjacent the outlet
of the second conduit, i.e., at the end of the first conduit remote
from the inlet which is coupled to the pump.
Preferably the first and second conduits 31, 75 are coupled
to a base fitting 23, which is shown in Fig. 2. The base fi~ting
23 has distinct couplings for the first passageway (i.e., for the
space between the outside of the second conduit and the inside of
the first conduit), and for the second passageway (the space within
the second conduit). The first passageway is coupled via fittings
21 and 24 to the system and the second passageway is coupled via
fittings 25 and 2t). The base fitting 23 has a larger diameter
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coupling for the first passageway and a smallar diameter coupling
for tha second passageway. The smaller diameter coupling extends
through a wall of the base fittin~ and terminates in a nipple 25
within the first conduit for receiving a tube defining the second
conduit 75.
The base fitting 23 in the embodiment shown in Figs. 2 and 4
is symmetrical, having lines for connection of two opposite first
and second conduit arrangements. It is also possible to use a
single first/second conduit arrangement as shown in ~gs. 5-7, or
to have more than two. The opposite conduit arrangement is
particularly applicable to use on aircraft and the like, wherein
the fittings for pumps and the like coupling the conduits to the
reservoir ar~ conveniently located centrally, with the conduits and
nozzles spaced along a line transverse to the direction of travel
of the aircraft. In a ground based apparatus of a similar type,
a one conduit arrangement is convenient with the couplings at one
end, if the nozzles are to be disposed lat~rally of a vehicle,
e.g., for treating vegetation along the side of a roadway.
In an aerial spraying embodiment, the first conduit 32
preferably comprises an elongated boom with an aerodynamic cross
section as shown in Fig. 1. The leadin~ edge 32 of the boom is
smooth, and the nozzles 42 and orifices 57 are spaced along a
trailing edge 33 of the boom. The boom can be sectional as shown
in Fig. 2, with internally threaded rearward stubs 2~, fnr
attaching the nozzles 42 to the boom in a manner that does not
substantially disturb a smooth laminar flow of air over the boom.
The boom sections have end flanges which mate with the flanges ~1
of the base fitting 23, or with similarly shaped flanges on end
covers which close the ends of the boom. Suitable gaskets are
preferably placed between the respective flanges for sealing.
Whereas an important objective of the invention is to provide
and arrangement wherein the surface tension of the emitted li~uid
is a primary parameter affecting the formation of droplets, the
preferred embodiment as shown is quite aerodynamic and does not
disturb the laminar flow of air over the boom or first conduit 31.
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The nozzles 42 on the trailing edge of the boom each lnclude a
substantially tubular housing 54 leading smoothly from the trailing
edge 33 of the boom 31 to a wedge shaped terminus 55. The wedge
shaped terminus defines a horizontal line of outlet openings 57.
Preferably, as shown in Fig. 1, the orifices are defined by narrow
tubes which are inserted into the nozzle body along a horizontal
line at the terminus. It is also possible as shown in Fig. 3 to
form the orifices directly in the material of the nozzle body. The
nozzle body can for example be-plastic, with stainless inserted
tubes for the orifices.
The outlet openings are capillary sized for the viscosity of
the li~uid agent being emitted, for example an agent which is quite
thin, approaching the viscosity of water. The flow paths leading
to the outlet openings extend to an internal manifold 52 in the
nozzle housings, as shown in Fig. 3. This manifold is formed by
a transverse bore through the body of the nozzle, the ends of which
are closed by a complementary bolt and threaded tube pair 49, which
define a shaft of slightly smaller diameter than the internal
diameter of the manifold. The manifold equalizes the pressure
across the flow paths to the orifices 57.
The nozzle body is made in three sections, including the rear
section including the manifold 52 and orifices 57, a central
section including a check valve 51 coupled between the first
conduit and the manifold, and a forward section defining an
aerodynamically smooth cowling that reaches over the trailing edge
33 of the boom 31. These parts fit together and over the trailing
edge stubs 26 of the boom (see Fig. 2). The check valve 51 has a
nut portion that sxtends laterally between the tapering front part
56 and the rear part of the nozzle housing where the discharge
orifices protrude rearwardly. The body portion of the check valve
can also be knurled. The rear part of the check valve seals to the
rear housing part at an O-ring 46, and threads into the rear part
of the nozzle body at a threaded bore leading to the manifold. The
check valve has a through bore terminating in the rear at seat 44.
A valve body 48 having a sealing O-ring 45 resides at the seat ~4
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and has a threaded shaft extending through the body of the check
valve. On the front side the shaft of the valve body 48 extends
through a compression spring ~3 and threads into adjusting nut 53.
The pressure at which the valve opens is determined by the pressure
exerted by the compression spring between the adjusting nut 53 and
the body of the check valve.
Tha ad~usting nut 53 and spring 43 are small enough in
diameter to fit within the threaded opening in the trailing edge
stubs 26 of the boom 31. The threaded front of the valve body is
screwed into a stub 26, thereby holding the tapering front 56 of
the nozzle on the trailing edge of the boom and placing the rear
of the nozzle in position on the trailing edge. Accordingly, the
check valve, and in particular the valve body biased by the spring
closes the opening through the check valve between the first
conduit and the manifold.
The means for delivering the agent from the reservoir 73 to
the first conduit or boom 31 includes at least one pump 63, 64, 65
coupleable to the reservoir 73. There are a number of ways in
which the at least one pump can be arranged, in order to pump the
liquid into both the first and second conduits for discharging the
liquid by opening the check valves, and also to recirculate the
liquid through the system with the check valves closed, and thus
to agitate the li~uid and keep it in proper suspension.
With reference to Figs. 5, the pump ~5 can be associated with
a valve means 83, shown schematically. The valve means 83 and pump
65 direct the flow from the reservoir 73 into both the boom 31 and
the second conduit 75 in the discharge mode. In that case the
inlet 64 to the pump 65 is coupled to the reservoir and the outlet
6~ is coupled to both conduits. Althou~h a pressure drop would
normally be experienced along the boom 31 due to the orifices along
the boom, which are opened with sufficient pressure to open the
check valves. However, by directing flow into both conduits, the
pressure at the outlet 76 of the inside (second) conduit 75 tends
to remain near the pressure at the inlet 77 to conduit 75. This
keeps the pressure at the respective nozzles more constant.
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The pump and valve means in the dischargs or delivery mode to
control flow of the agent into both the first conduit and the
second conduit in parallel. In a recirculating mode, however, the
position of the valve means and/or the operation of the pump are
changed, to control flow into one of said first and second conduit
only. The other of the first and second conduit being couplea~le
to the reservoir for recirculating the agent along a path including
the first and second conduit in series.
The pump as shown in Fig. 6 can be arranged to produce a
negative pressure in the first conduit in the recirculating
position of the valve means, i.e., having an inlet 70 to the pump
coupled to the boom or first conduit, and an outlet 66 coupled to
the reservoir. According to this embodiment operation of the
recirculating means positively prevents leakage of the agent from
the boom, even if outlet orifices are open due, for example, to
removal of an outlet check valve for servicing, or due to one of
the outlet valves being stuck open. Loss of the agent is prevented
because negative pressure in the conduit draws air in through the
open outlet rather than allowing the agent to flow out. It is also
possible in this manner to drain the conduit into the tank, i.eO,
by closing the return flow path from the tank to the conduit and
allowing ingress of air through a valve disposed in the surface of
the conduit.
The pump can be associated with a valve means (not shown) that
reverses the connection of the lines between the boom and the
reservoir, or the pump itself can be reversible. In any event, in
the recirculation mode, the reservoir is coupled to the second or
inner conduit, and the pump recirculates the material by drawing
the liquid out of the boom. The reduced or negative pressure in
the boom is such as to close the check valves 51, cutting off flow
through nozzles 42 and preventing leakage. The flow proceeds
serially through the internal conduit to the remote outlet 76, and
back through the boom 31 serially, to the reservoir through pump
64. This flow, which can be conducted preliminarily before opening
the check valves with sufficient pressure, or periodically,
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agitates the contents of the reservoir and in connection with
inverts provides a good oil and water mix.
An alternative embodiment is shown in Fig. 7, and includes two
pumps. A first pump 63 is coupled to force the agent from the
reservoir into the first conduit 31, i.e., having an inlet 69
coupled to the reservoir 73 and an outlet 68 coupled to both of the
two conduits 31,75. It is not necessary in this embodiment to
include a valve means at the outlet 68 of the pump and the inlet
77 to the internal conduit 75. Instead, a second pump 64 is
coupled to force the agent from the first conduit 31 into the
reservoir 73, i.e., the pump having an inlet 70 coupled to the
first conduit 31 and an outlet 66 coupled to the reservoir 73. The
first pump 63 in this embodiment is of a type which will permit
flow through the pump when the pump is not operating, for example
a centrifugal pump as shown. The recirculating pump 64 can be a
positive displacement pump or a centrifugal pump. If both pumps
are centrifugal the contents of the reservoir 73 will be routed in
a loop if either of the pumps is operating. If only the
recirculating pump 6~ is operated, the pressure in the boom 31 is
reduced and only agitation occurs. If only the primary or
discharge pump 63 is operated, the pressure in the boom 31 builds
(being equalized along the length of the boom due to action of the
second conduit 75) until the check valves open and the liquid is
discharged.
The choice of a positive displacement pump or a centrifugal
pump is dictated to some extent by the character of the liquid
agent to be discharged. In connection with thin invert emulsions,
the viscosity of the liquid is increased with agitation, and it is
desirable to keep the emulsion thin enough to be readily discharged
through the capillary sized orifices in the nozzles. It is
possible to monitor the back pressure of the flow, for example the
back pressure on the nozzles, in connection with a control system
for varying the time period or frequency of agitation in an ongoing
manner.
The connections made throughout the system can be made with
PHL: PHLDATA: 7 23 1. WP5: Septembe r 24, 1992
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flexible plastic tubes. For example, the connection between the
reservoir and the boom or interna:L conduit and the connections
between the base fitting 23 and the second conduit can be
accomplished using flexible tubes. For this purpose, as shown in
Fig. 4, a larger nipple 24 is provided for coupling to the
discharge pump and smaller nipples 25 are provided for coupling the
base fitting to the second conduit. The flexible tubes can be
resiliently held on the nipples via their natural compression, or
clamps can be provided to ensure that pressure does not cause the
connections to come apart.
The invention provides an improved aerial or ground vehicle
based delivery system for a liquid, having a boom 31 to be passed
over a treatment site with an internal opening 61 and a plurality
of outlet orifices 57 spaced along the boom, and means 63, 65 for
moving the liquid into the boom 31. In connection with an
aerodynamic or aerial arrangement the improvement inaludes the boom
31 having an aerodynamic cross section with a smooth leading edge
32 and a tapering trailing edge 33. The means for moving the
liquid into the boom includes at least one pump 63, 64, 65 coupled
to the internal opening 61 and operable to supply the liquid to the
internal opening at pressure. ~ plurality of wedge shaped nozzles
42 are disposed along the trailing edge 33 at the outlet orifices,
the wedge shaped nozzles being joined smoothly to the trailing edge
and tapering rearwardly into a horizontally elongated edge. The
nozzles 4~ each have an internal manifold 52 coupled to the boom
31 through a check valve 51 at one of the outlets, the check valve
51 opening under the pressure of the liquid. A plurality of tubes
50 or 58 lead rearwardly from the manifold 52 to the horizontally
elongated edge.
The tubes are capillary sized for emitting uniform small
droplets, and surface tension of the droplets is the primary
parameter affecting the droplet size. When the pump or similar
means for moving liquid into the boom is activated the liquid is
emitted throu~h the plurality of tubes 50 or 58 and broken into
droplets due to surface tension of the liquid. When the means for
PHL: PHLDATA: 723 1 .WP5: SepteDb~r 24, 1992
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moving liquid into the boom is deactivated, further emission of the
liguid ceases abruptly with closure of the check valves 51.
A conduit 75 is disposed within the internal opening 61 of the
boom 31. A reservoir 73 stores the li~uid. The internal opening
61 of the boom 31 and the conduit Y5 are coupled to at least one
pump 63, 64, 65 at a first point 23, 25 on the boom and the conduit
75 has an outlet opening 76 within the boom 31 at a point remote
from the first point, whereby flow of the liquid through the
conduit reduces a pressure differential along the boom from the
first point 23, 25 to the point 76 remote from the first point.
Valve means 83 can be coupled between at least two of the pump
65, 64, the boom 31 and the conduit 75. The valve means 83 are
controllably operable to define a discharge mode wherein flow of
the liquid driven by the pump is directed from the reservoir into
both the boom and the conduit in parallel (Fig. 5), and a
recirculating mode wherein the flow of the liquid is directed in
a loop, through the boom 31 and the conduit 75 in series (Fig. 6),
the loop including the reservoir 73. In the recirculating mode the
pump is coupled to pump the liquid from the boom 31 into the
reservoir 73, thereby producing a negative pressure in the boom 31
which closes the chec~ valves. The valve means can be operable in
the recir~ulating mode to couple the conduit 75 directly to the
reservoir.
Two or more pumps can be provided, as in Fig. 7. One pump 63
can be operable in the discharge mods to move the liquid from th~
reservoir 73 into the boom 31 and into the conduit 75, and a second
pump 64 can be operable in the recirculating mode to move the
liquid from the boom 31 into the reservoir 73. The first pump 63
can be arranged to pass the liquid (under power of the second pump)
when the first pump is deactivated.
The invention having been disclosed in connection with certain
exemplary embodiments, variations on the concept in accordance with
the scope and spirit of the invention will now become apparent to
persons skilled in the art. Reference should be made to the
appended claims rather than the foregoing specification in order
PHL:PHLDATA:723 l.~lP5:Septcmber 24, 1992
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18
to assess the scope of the invention in which exclusive rights are
claimed.
P8L:P8LDAT.a:723 l.WP5:S~ptemb~r 24, 1992
