GB2470204A

GB2470204A - Self-acting watering device

Info

Publication number: GB2470204A
Application number: GB0908186A
Authority: GB
Inventors: Jim Laflin
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-05-13
Filing date: 2009-05-13
Publication date: 2010-11-17
Also published as: GB2470275A; GB2470275B; GB0908186D0; GB201007879D0

Abstract

A self-acting watering device for watering a plant-supporting matrix comprises a holding tray30, a conduit20arranged between the holding tray and the matrix; and container7located in or connected to the holding tray30. The container7has one or more holes11,15in a basal region, and these one or more holes are below the rim of the holding tray30. There may be two holes wherein one hole is positioned higher than the other. The two holes may have different sizes, shapes or cross-sectional area. The container7may have a flange10and the conduit20may be positioned between the flange7and the matrix. The device may have means in the form of a stick to control the flow rate of water or plant nutrient, pesticide or fungicide through the one or more holes by opening, closing or restricting the holes.

Description

Controlled Moisture Release Device

Field of Invention

This invention relates to self-acting watering devices, e.g. for flower pots and other horticultural applications, using conduits, wicks and the like.

Background of the Invention

The rate of supplying moisture to plants in many applications is controlled mechanically by float valves or by valves which may be electrically operated.

Plant containers are available which have a liquid storage tank on the bottom, and there are others that have hollow walls able to supply water or other suitable liquid to a tank at the base of the container, and the liquid is drawn up from the tank into the root area by means of wicking. These are much better than applying water to the top of the plant container. However such systems may be complex and expensive and can only be purchased as containers that include the water supply system.

The conventional top watering method tends to saturate the soil in a contaTher, and much of the water supplied s lost through the draThage holes which are provided to prevent saturation. Furthermore, as the roots of the plants take up the moisture, the degree of saturation reduces. The variation in saturation levels means that the roots of plans in the container only have the ideal level of moisture for short periods. They are either too wet, or they are not wet enough, and if water or other suitable liquid is not applied at regular intervals, the plants may dry out and die. Furthermore, applying water to the top of a container means that a significant amount is lost through evaporation.

This can also happen in capillary fed systems where liquid continues to be drawn up from a basal container up through the capillary supply wicking into the growing matrix. When plants are small and their roots do not take in much liquid and the weather, moisture rises up through the growing matrix until it reaches the surface where it is subject to evaporation. This effect is even worse when the weather is cold and there is little evaporation from the surface of the growing medium. Indeed, many systems put a layer of shingle over the surface of the growing medium with the specific objective of minimising evaporation. In these circumstances, moisture is still drawn up through the wick into the growing medium, and the growing medium itself begins to draw up water through capillary action. The result of this is that the growing medium can become saturated to the detriment of plants growing therein.

This system is ideal, for example, for supplying moisture to the roots of plants in closed containers and baskets, where the conventional method is to apply water to the surface of the container rather than directly to the roots of the plants.

The prior art (U.S. Patent Appl. Pub. No. 2008/0263948A1; U.S. Pat. No. 6,131,333; U.s. Pat. No. 4,819,375; FR2561064 and GB0874729), discloses approaches in which water is drawn by capillary action directly from a storage vessel into the plant supporting matrix. This arrangement has a tendency to over-water, as the liquid is drawn out of the storage container even when the plant-supporting matrix is quite damp.

Disclosure of Invention

From the foregoing, it may be appreciated that a need has arisen for a device that separates the seepage of water out of a storage container from its subsequent capillary transfer to the plant-supporting matrix. This invention uses atmospheric pressure to maintain a constant level of supply, and the rate of fluid flow is substantially controlled by the rate of consumption by the plants. It also enables a limit to be set for the maximum rate at which liquid can be drawn up through the wicks thereby preventing saturation of the growing matrix when there s little demand from the plants n the contaTher.

The present invention is a self-acting watering device for watering a plant-supporting matrix. It has a holding tray (30), a conduit (20) arranged between the holding tray and the matrix; and container (7) located in the holding tray. The container has one or more holes (11, 15) in a basal region, and these one or more holes are below the rim of the holding tray. When the container holds a liquid suitable for watering the plant-supporting matrix: (1) the liquid flows into the holding tray out of at least one of the one or more holes thereby increasing a quantity of liquid in the holding tray, (2) the liquid flows out of the holding tray to the matrix via the conduit thereby decreasing a quantity of liquid in the holding tray, (3) if the flow of liquid out of the holding tray is less than the flow of liquid into of the holding tray, a level of the liquid in the holding tray rises until it reaches the position of at least one of the one or more holes, whereupon liquid is prevented from flowing into the holding tray, and (4) if the flow of liquid out of the tray is greater than the flow of liquid into the tray, a level of liquid in the holding tray falls until it reaches a position below at least one of the one or more holes, whereupon liquid flows into the holding tray out of at least one of the one or more holes thereby increasing a level of liquid In the holding tray.

and this means that a variable demand for liquid by one or more plants in the plant-supporting matrix comes from a constant level of water in the holding tray. The rate of moisture flow through the wicking system is substantially controlled by the degree of wetness at each end, and the only variable in the rate of moisture supply is therefore the degree of wetness in the plant matrix. This is determined by the rate at which plants absorb the moisture, and to a lesser extent by evaporation from the surface of the growing matrix.

Brief Description of Drawings

For a more complete explanation of the present invention and the technical advantages thereof, reference is now made to the following description and the accompanying drawing in which: Figures la-c are diagrammatic representations of various embodiments of the present invention; Figure ld is a plan view showing possible arrangements of storage container and holding tray; Figure 2 is a drawing of an embodiment of the present invention, with enlarged representations of the flange (Figure 2a), arrangement of holes (Figures 2b-d), an extension tube (Figure 2e) and 0-rings for providing a seal (Figure 2f); Figure 3a are various shapes of hole that are suitable for use in the invention; Figure 3b shows an embodiment in which wicking material passes through a hole; Figure 4 shows an embodiment in which the storage container of the watering device is replenished from a larger container; Figure 5 shows an embodiment in which the storage container of the watering device is replenished from a larger mobile container; Figure 6 shows an embodiment in which a number of storage containers of the watering device are replenished from a larger mobile container via an intermediate container; Figure 7 shows an embodiment in which a number of plant containers may be served by a single device; Figure 8 shows an embodiment in which the container is removable for filling; Figure 9 shows a planter having the device of the present invention; Figure 10 shows approaches for controlling the flow of liquid from the device; Figure 11 shows an alternative configuration of the present invention that utilises a vent; Figure 12 shows integrated and separate embodiments of the invention; and Figure 13 shows various hole arrangements and topologies.

Best Mode for Carrying Out the Invention

Embodiments of the present invention and their technical advantages may be better understood by referring to Figures 1 to 11.

Referring first to Figure la, a storage container (7) having a sealable opening (1) and a basal end is located in a holding tray (30) in any convenient position. The basal end has one or more holes which are below a rim of the holding tray when the storage container is located therein. In the embodiment shown in the drawing, two differently shaped holes are shown, one circular hole (11) being higher than the other rectangular hole (15) The storage container holds water or any other liquid used for irrigation of plants, or routinely used in horticultural practice and includes nutrient solutions, pesticidal solutions, and fungicidal solutions. When filled and sealed, water or other liquid will seep out of the one or more holes into a holding tray or tube until the holes are covered. At this point air cannot enter the storage container and atmospheric pressure holds the remaining liquid in the container. Liquid may be taken from the holding tray (30) by means of pipes, tubes or capillary wick. Capillary wicking (20) communicates between the holding tray and a growing medium to be irrigated (not shown) As liquid from the holding tray is drawn up into the growing medium through the capillary wicking, the level in the holding tray falls until it reaches a point lower than the hole, or the uppermost hole if there is more than one and they have different vertical positions. At this point air can enter the storage container through the hole, or the uppermost hole if there is more than one and they have different vertical positions, and water or other suitable liquid can flow into the holding tray until the depth of water or other suitable liquid in the tray again covers the hole completely, or to a point where a meniscus inside the container prevents the ingress of air, or the uppermost hole if there is more than one and they have different vertical positions. At this point atmospheric pressure prevents further release of liquid from the storage container.

Referring now to Figure lb, which shows a further embodiment of the invention, a flange (10) is located on the storage container. The flange acts to prevent extraneous material from falling into the holding tray, and also serves as a support for the capillary wicking. The flange may be extended beyond the perimeter of the holding tray as shown in Figure lc: here the flange acts as a support for extended capillary wicking, and also as a support for one or more plant containers (52) . The capillary wicking thus extends from the holding tray, through the flange and underneath the plant containers.

Referring now to Figure 2, an alternative arrangement is shown, where the capillary wicking (20) is brought up through one or more slots (13) in flange (10) that allows liquid in the holding tray to pass, and capillary mat (17) is laid over the capillary wicking which distributes moisture evenly over the base of the plant container (not shown) . The capillary wicking can therefore comprise one or more capillary elements.

The rate of flow through the capillary wicking may be adjusted by selection of the capillary material used and the cross sectional area of that material.

Referring now to Figures 2b and 2c, the presence of atmospheric pressure at holding tray (30) maintains liquid in storage container (7) as long as the hole, or the uppermost hole if there is more than one and they have different vertical positions, are covered.

The operation of this system is not dependent on the size, shape or number of holes in the liquid storage container. For example, a combination of a small circular seepage (15) hole and a much larger triangular hole (11) may be utilised, as shown in Figure 2d. This combination of sizes and shapes for example works perfectly well. Any of the hole shapes illustrated in Figure 3a may be used, but circular vents are preferred where the storage column vent is made by a drilling process. However when the storage column is manufactured by a moulding process, the shape of the vent has minimal cost implications. Circular vents are preferred if the contents of the storage column are a high viscosity substance.

Referring to Figure 3b, which shows storage container (7) having single hole (15), the single hole allows the seepage of water into the holding tray and the entry of air into the storage container. The rate at which liquid (36) flows from the storage container to the holding tray may preferably be increased by increasing the size of the hole, or by introducing capillary conduit (302) which passes through the hole. In this latter embodiment, anchors (304) prevent the capillary conduit from falling into or out of the container. An example of a suitable capillary conduit with anchors at either end is a treasury tag. This approach overcomes a situation in which the meniscus that forms across the hole effectively seals the hole, preventing the entrance of air and the exit of liquid.

Referring now to Figures 2e and 2f, which show an extension tube (40) having 0-rings (4), the amount of liquid stored is increased by plugging the extension container into the top of the storage container. 0-rings at the base of the extension tube form an airtight seal when the extension tube is plugged into the storage container. The combined storage container / extension tube may then be filled and closed using the stopper (6) . An alternative equally preferred method of increasing storage capacity is by connecting a parallel container or containers to an existing container as illustrated in Figure 4. In this configuration, a large storage container (60) supplies liquid to a smaller container (7), which may in turn supply moisture to a plurality of growing containers (not illustrated). An air line (53) connects the two containers at a point which is preferably near the top of each container, and a water line (50) connects the two containers at a point which is preferably near the bottom of each container. Two valves (62) and (65) are available to isolate the containers. In normal operation valves (62) and (65) are open. As moisture is taken from container (7), through seepage holes as illustrated in earlier illustrations, air is taken in through those same holes to replace it. This air rises to the top of container (7) and passes on to container (60) via airline (53) and valve (65) . An equal volume of liquid then flows from container (60) to container (7) via valve (62) and water line (50) . A large container (60) may supply a plurality of smaller containers (7) . When container (60) needs to be refilled, the valves (62) and (65) are closed. The smaller container (7) will continue to supply moisture as described above regardless of the condition of valves (62) and (65) . When container (60) has been refilled, the cap (57) must be replaced firmly so that washer(55) establishes an airtight seal. At this point valves (65) and (62) may be reopened, whereupon accumulated air in the container (7) passes through air line (53) and valve (65), and a corresponding volume of liquid from container (60) flows through valve (62) and water line (50) to replace it. Storage containers do not have to be permanently mounted. Figure 5 shows a large storage container (61) which is conceptually identical to container (60) in Figure 4. However this container may be mounted on a vehicle. The operation of valves (62) and (65) on this illustration are identical to the above paragraph. Figure 6 illustrates a mobile container (61) feeding an intermediate storage container (60), which in turn feeds one or a plurality of individual containers (7) . In this configuration the liquid level of all individual containers is effectively the same as level (70) in the intermediate container (60) . In the event that the intermediate container (60) becomes exhausted, the individual containers will continue to supply their plant containers until they are also exhausted.

In this event the circled container illustrated in Figure 6 will run out of water before the lower containers because when the level of water in the intermediate supply container (60) falls, it will get to a point where it cannot fully refill the higher circled container. When the intermediate supply container (60) is exhausted, the circled container will then act as a supply container to all containers at a lower level.

Priority can therefore be given to individual containers with the lowest container always being the last one to run out.

Referring now to Figure 7a, which shows a further example of a supply system which is located externally to a plant container, capillary wicking (20) delivers moisture to a plant container (52) in a similar fashion as that shown in Figure lc. In this embodiment, capillary wicking has a cover (51) of impermeable material that protects the capillary wicking from direct sunlight or drying winds which will take moisture from the system by evaporation. This is easily achieved by, for example, wrapping the capillary conduit loosely in plastic film, or covering it with impermeable material, or by passing the conduit through a tube, such as a plastic drainpipe or similar shielding container. Many watering systems rely on a supply of water being held at a level in which plant containers may be stood. The wicking system obviates this need, and it is equally suitable for moving moisture to a higher or lower level. Figure 7b illustrates a single storage container (7) supplying moisture to a plurality of containers (52) through capillary wicking (20), optionally protected by cover (51) described above (not shown) . It is preferred that a separate capillary wick (20) is used to each container (52) Passing a single wick through a series of containers is not preferred since the first container on the line may be oversupplied, and the last container on the line may be undersupplied. There is no reason why the container (7) should not be a high capacity container. For example a 100 litre or 1,000 litre may be suitable for agricultural use. If plants are to be grown in containers in an area where there is no mains water supply, then delivering water in bulk from a container mounted on a lorry or tractor is much cheaper than laying on a mains supply in a trench which must be at least lm deep.

Furthermore, if the new location is in a garden, then the destruction or disruption caused by digging such a trench may not be acceptable.

Circumstances can arise, for example when the storage container (7) or the pot or planter disclosed below and shown in Figure 9 (33) is suspended at a high level, when it may not be easy to refill it. It is therefore advantageous to make provision for a storage container which is removable to facilitate refilling. Such a provision is shown in Figure 8, in which storage container (7) can be removed from the plant container illustrated in Figure 9 for filling and refilling. This may be conveniently arranged by providing a sleeve (804) into which the storage container may be easily inserted or removed, and which has holes to allow liquid seeping out of the container to collect in the holding tray in the manner described above. The storage container is similar to those described elsewhere in this document with a seepage hole (15) and a stopper (6) . In this embodiment, the flange (10) and holding tray (30) are attached to the sleeve or moulded as part of that sleeve. In the refilling process, the storage container is removed, and after removal of the stopper the container is refilled. It may be convenient to close the seepage hole (15) by placing a finger over the hole in order to prevent loss of liquid while the container (7) is being refilled. Once the refilling process is complete, and stopper (6) is replaced, atmospheric pressure will hold the liquid in the container, and removal of the finger over hole will not cause any significant loss of liquid. When the storage container has been refilled, it is replaced in the sleeve and liquid seeping from the hole will go into the holding tray, and be taken by capillary action in the wicking into the growing medium in the container as already described.

It may be convenient to fill a number of storage containers in advance. This will enable the empty container to be removed and replaced with a full container without the need for on-site refilling. This process would be convenient for example, when servicing a multiplicity of plant containers in a municipal application.

The storage container may be any suitable or convenient shape. For example, square, rectangular or cylindrical shapes are preferred for the convenience of production and distribution. Factors which need to be considered when deciding the size of the storage container include for example, the viscosity, the volume and the chemical constituents of the liquid to be stored within it. The size and shape of the container do not affect the way in which the system delivers moisture in proportion to the rate of demand, and those who are skilled in the art will understand that this invention includes all containers regardless of their shape. Furthermore, the storage container may be positioned in any convenient location within the holding tray, and the holding tray may be of any suitable size or shape. Some possible arrangements of holding tray and storage container are shown in Figure ld. The tube or holding tray may be shallow in comparison with the depth of the flower container.

Referring again to Figure 1, sealable opening (1) is made airtight, for example by means of a stopper or a screw plug fitted with an 0-ring.

A stopper (6) with an 0-ring (4) is shown in Figure 2, which is a more detailed drawing of the device described in the foregoing. When the stopper, which typically has a chamfer (2) is removed, water or other suitable liquid may be poured into the storage container (7) . During this process the liquid will flow into the holding tray (30) through holes (11) and (15) . When the stopper is tightly replaced, air entrapped in the spatial volume in the underside of the stopper (6) may cause liquid to be forced out through the holes (11) and (15) and the 0-ring forms an airtight seal.

In the foregoing, the controlled moisture release device has generally been disclosed as an item separate from the growing medium in the pots or planters. It is to be understood that the device may also be easily and conveniently integrated into a pot or planter. This embodiment may be better understood by reference to Figure 9, which shows a pot or planter (33) in which the device shown in Figures 1 and 2 is located. Flange (10) serves to prevent the nutrient matrix from falling into holding tray (30), and a free flow of air enters through holes (23) in the base or sides of the container (33), passes between the pebbles or shingles (27), and thence through a gap (14) between the holding tray (30) and the flange (10) . In operation, container (7) is filled through a top entrance which is then sealed and made air-tight, preferably by means of a stopper or a screw plug (6) which is fitted with an 0 ring (4) . The storage container has holes in the bottom which allow liquid to seep into a tube or holding tray (30) . Liquid (36) in the storage container described herein is retained in the container by atmospheric pressure, and is released into a liquid holding tray where the level is held constant. If the liquid holding tray is supplying moisture to the roots of plants in a flower basket or trough, the liquid may for example be water, or water containing fertiliser. When the depth of liquid in the tray is sufficient to cover the holes in the lower part of the container, atmospheric pressure prevents further liquid from seeping out and the depth of liquid is held constant at that level. The liquid in the holding tray is drawn up into the plant root area by capillary wicking (20) and distributed evenly over the base of the plant container by means of a capillary mat (17) The rate of flow through the capillary wicking is controlled by the degree of wetness at either end. Thus on a rainy day when water permeates down through the soil, then both ends of the capillary supply may be equally wet and the flow through the capillary system is minimal. However on a hot sunny day when the plants are taking moisture out of the soil around their roots, the end of the capillary system in the soil is much drier than the end which is in the holding tray and the flow of liquid through the capillary system increases.

As the capillary system draws liquid out of the holding tray, the level falls to a point where the holes which allow liquid to seep into the tray are no longer covered. At this point air can enter the storage container and liquid again flows into the holding tray. This process continues until the holes are covered at which point air can no longer enter the container, and the remaining liquid is again held in the container by atmospheric pressure.

Thus the rate of liquid supplied from the storage container is controlled by the rate of demand. This in turn is proportional to the size of the plants in the container and the weather. With an abundant and constant supply of water or other suitable liquid, and a constant distance between the liquid supply and the growing medium, the rate of capillary transfer is directly proportional to the wetness or saturation level of the growing medium. This in turn is dependant on the rate at which plants in the container are absorbing moisture and any other losses which may be incurred as a result for example, of evaporation. However evaporation may be minimised by covering the surface of the growing matrix for example with pebble or polythene.

Referring now to Figure lOa, which illustrates how the rate of flow through capillary wicking (20) may be controlled by inserting (1018) or withdrawing (1020) an externally accessible flow rate control stick (1002) Movement of the stick modifies the width of slot (13) in flange (10) by means of tapering wedge (1004) This in turn compresses the capillary wicking or allows it to expand so that the flow rate is respectively decreased or increased. The tapering wedge may have a plurality of thicknesses, and in Figure 10a a wedge with three thickness is shown to illustrate the principle. In this example the wedge thickness at (1006) exerts no pressure on the capillary wick and therefore has no affect on the rate of moisture flow through the wick, a second thickness (1008) where the capillary material may be partially compressed and the flow of liquid the material is restricted, and a third level (1010) where the capillary material is substantially compressed and the flow of liquid through the material is substantially reduced. The slots may be mounted in a flange 10 (see Figure 2a) which may be moulded as part of a storage container (7) or sleeve {Figure 8 (10) }.

The seepage holes in the liquid container may be closed by means of an extended flow rate control stick as illustrated in Figure lOb. This embodiment is advantageous when refilling a water containers in situ. With the air tight stopper removed to enable the container to be filled or refilled, there is no differential atmospheric pressure to hold water in the container, with the result that it flows out through the seepage holes without restriction. Figure lOb illustrates an extended rate control stick having on one end a wedge (1012, see Figure lOc) . A foam cushion (1014) is attached to storage container (7), preferably by means of a suitable adhesive, so that it is positioned over the holes (15) As the rate control stick slides to up and down, the foam cushion is either uncompressed in which case liquid may flow through the material, it is compressed over a single hole as in Figure lOc, in which case the flow from that hole is restricted, or it is compressed over two holes in which case the flow from the storage container is severely restricted. Figure lOd shows an equally preferred method of closing the seepage holes, in which the foam cushion is attached to the wedge rather than to the storage container as in Figure lOc. Here again the illustration shows the sliding wedge in a position to cover one of the two holes. Figure lOe illustrates a third equally preferred closure method whereby closure flaps (1016) cover the seepage holes, and as the rate control stick slides to the up and down, one of the two flaps over the holes has been pushed closed by the wedge. A similar closure could be achieved by rotational adjustment of a suitable shaped rate control stick, and the movement of the stick could be caused by manual or electrical action. Those familiar with the art will understand that this patent covers all means of closing these holes.

In an equally preferred embodiment illustrated in Figure 11, vent pipe (104) forms a direct air connection between holding tray (30) and the top of storage container (7) . Considering Figure lla, when stopper (6) is pushed into the top of the vessel, it acts in a fashion similar to a pump. Air entrapped in spatial volume (102) in the underside of the stopper is pushed down the air vent (104) thereby clearing the vent. With a clear air path from the top of the storage container (7) to the holding tray (30) water freely flows out of the container through seepage vent (15) and into the holding tray (30) . At some point the level of water in the holding tray covers the bottom of vent (106), at which point the flow of water into the holding tray (30) ceases. As water is drawn out of the holding tray by capillary action as described previously, the level of water in the tray falls until the bottom (106) of the air vent is uncovered. At this point, water can again flow out of container (7) until the bottom of the vent pipe is again covered, and the flow again ceases.

In an equally preferred embodiment where there may be no air supply path through the base of the plant container, an air supply line {Fig llc (5) } may run alongside the container (7) into the holding tray area.

Figure 12a illustrates an embodiment in which the holding tray (30) is an integral part of the container moulding. Figure 12b illustrates a second embodiment in which the holding tray (30) is separate from the container moulding. Both embodiments are equally preferred.

Example 1

The preferred diameter (31), of the flange (10), and its height above the base of the holding tray (30), is entirely dependent on the size and capacity of the storage column, (7) . Referring to Figure 2b, a hole (11) is positioned at a preferred height of between 10mm and 100mm above the base of the holding tray. A slot (15) may be located at a height of preferably between 2mm and 10mm above the base of the holding tray (30) . The depth of the slot is preferably in the range 2mm to 10mm, and the width of the slot is preferably in the range 10mm to 50mm. Referring to Figure 2c, a hole (11) is positioned at a preferred height of between 10mm and 100mm above hole (15) and the preferred height of hole (15) is between 2mm and 10mm above the base of the holding tray (30)

Example 2

Seepage of liquid from the sealed vessel requires a balancing counter flow of air into the storage vessel, and this determines the features of the orifice.

A single hole is possible, but it is preferably over a certain size so that the meniscus that forms over the hole is not strong enough to prevent the ingress of air and the egress of liquid. This depends on the surface tension of the Thqud used. The size of the hole can be easily determThed empirically, and my experiments indicate that if it is of the order of 6mm diameter then the meniscus will give way and bubbles go in through the orifice to release the vacuum inside the storage container, allowing liquid to seep out.

Several experiments on hole sizes have been performed: Hole size 3mm, 4mm, 5mm produced no flow at all.

Hole size 6mm, the level of water in the holding tray sat at the bottom of the hole. Bubbles as expected.

Hole size 6.5mm, the level of water in the holding tray sat approx 1mm up from at the bottom of the hole. Bubbles as expected.

Hole size 7mm, the level of water in the holding tray sat approx 1.5mm up from the bottom of the hole. Bubbles as expected.

Hole size 8mm, the level of water in the holding tray sat approx 4mm up from the bottom of the hole. Bubbles as expected.

No flow at 5mm suggests that the meniscus is able to support the weight of water up to approx 20 sq mm.

Flow at 6mm but water level at bottom of hole suggests that the meniscus broke down when the whole hole was exposed.

Breakdown area therefore approx 28sq mm.

Area with ho'e size 7mm = 38 sq mm but 1.5mm was covered so open area was less than 38 sq mm.

Example 3

Referring now to Figure 13a, in order to investigate whether the shape of the hole may affect the behaviour of the meniscus, a long vertical slot (15) was made in the wall of storage container (7) . Surface tension caused the water to form a shape as if it was piled up, with an overhang as shown, and prevented any water from flowing out of the storage container.

Water did not fiow out of the rectangular hole until it area was approximately 20 sq mm which is approximately the same area required for water to flow from a circular hole.

Example 4

Referring now to Figure 13b, in order to investigate whether the number of holes would affect the behaviour of the meniscus, two 3mm holes, one (11) above the other (15) were made in the wall of storage container (7) . No water (36) flowed out of the storage container and it was assumed that the meniscus which stopped water from coming out of the lower hole (15) hole, was mirrored by a similar meniscus which prevented air from getting in through the upper hole (11) Referring now to Figure 13c, which shows a variation in which upper hole (11) is angled upwards, water (36) flows out of the lower hole (15) when the hole diameters are greater 3.5mm for the lower hole and 4.5mm for the upper angled hole. With these sizes of hole, the level sits approximately as shown. For the angled hole, the point where it breaks into the cylinder will be an ellipse, as shown in Figure 13d. The smaller diameter of hole (13) will be the width of the drill i.e. 4.5mm, but the longer diameter will be much greater. Thus the surface area of the meniscus if probably the same as it was before, but it is possible that the wedge shaped air entry is exerting more force on a small part of the meniscus at the top of the hole. Once flow out of the lower hole begins, a stream of bubbles is observed, and the meniscus holds until quite a lot of water has seeped into the tray. This suggests that that there is quite a vacuum in the container, and when the first bubble gets sucked in, it pulls a few more after it. When the size of the lower hole was increased to 4.5mm, the level in the tray went up to about 1mm above the bottom of the angled hole.

If a small hole is located above a large hole, then the water level is set at the top of the large hole, the upper hole admitting air and the lower seeping liquid into a holding tray. If there are three vertical holes, the highest hole always appears to be the bubble entry hole. In this configuration the water level sits midway between the upper two holes.

A preferred combination is a lower circular of about 5mm diameter located as near the bottom of the container with a 2mm hole located about 10mm above it.

Example 5

Referring now to Figures 13e and 13f, which shows a hole having a pipe (1306) in a wall of storage container (7) containing water (36) . A drip (1308) is shown on the end of a pipe. In Figure 13b, the water in the drip might have run down to the sharp point on the end of the pipe, which means that the surface tension has very little area to cling to. The result is that the drip runs away (1310), and when that happens, surface tension might be pulling down the level of the running water leaving a void (1312) where air can enter.

Claims

Claims 1. A self-acting watering device for watering a plant-supporting matrix comprising: (a) a holding tray (30); (h) a conduit (20) between the holding tray and the matrix; and (c) a container (7) having a basal end located in the holding tray; characterised by said container having one or more holes (11, 15) in a basal region, said one or more holes being below a rim of the holding tray, such that when the container holds a liquid suitable for watering the plant-supporting matrix: (1) the liquid flows into the holding tray out of at least one of the one or more holes thereby increasing a level of liquid in the holding tray, (2) the liquid flows out of the holding tray to the matrix via the conduit thereby decreasing a level of liquid in the holding tray, and (3) if the flow of liquid out of the holding tray is less than the flow of liquid into of the holding tray, a level of the liquid in the holding tray rises until it reaches the position of at least one of the one or more holes, whereupon liquid is prevented from flowing into the holding tray, (4) if the flow of liquid out of the tray is greater than the flow of liquid into the tray, a level of liquid in the holding tray falls until it reaches a position below at least one of the one or more holes, whereupon liquid flows into the holding tray out of at least one of the one or more holes thereby increasing a level of liquid in the holding tray, whereby a variable demand for liquid by one or more plants in the plant-supporting matrix is met by the watering device.
2. The device of claim 1 in which the liquid suitable for watering plants is any liquid routinely use in horticultural practice and includes water, nutrient solutions, pesticidal solutions, and fungicidal solutions.
3. The device of claim 1 in which the container comprises a sealable opening (1) through which the liquid suitable for watering plants may be admitted.
4. The device of claim 3 additionally comprising an extension tube (40) having at one end a sealable opening and at the other end having 0-rings (4) 50 that it plugs into the sealable opening of the container, whereby the volume of the container is increased.
5. The device of claims 4 or 5 additionally comprising a stopper or screw plug (6) for sealing the opening.
6. The device of claim 1 in which the container additionally comprises an outer sleeve (804) attached to the holding tray and which has one or more holes to allow liquid flowing out of the container to flow into the holding tray, whereby the container is removable for filling.
7. The device of claim 1 in which the storage container is connected to an extension container (60) via a liquid line (50) which connects the two containers at a point near a base of each storage container and an air line (53) which connects the two containers at a point near a top of each container.
8. The device of claim 7 additionally comprising an isolating valve (62) on the liquid line.
9. The device of claims 7 or B additionally comprising an isolating valve (65) on the airline.
10. The device of claims 7, 8 or 9 in which the extension container is mobile.
11. The device of claim 1 in which the holes may be of any shape.
12. The device of claim 1 in which the container has one hole.
13. The device of claim 1 in which the container has at least two holes, and a first of the holes (11) is positioned higher than a second of the holes (15)
14. The device of claim 13 in which the first hole is positioned 2 -10 mm above a base of the holding tray.
15. The device of claim 13 in which the second hole is positioned 10 -100 mm above a base of the holding tray.
16. The device of claim 13 in which the second hole has a bigger surface opening cross sectional area than the first hole.
17. The device of claim 1 having a flange (10) attached to the container.
18. The device of claim 17 in which the flange extends beyond a rim of the holding tray.
19. The device of claim 17 in which the flange has one or more slots (13)
20. The device of claim 19 in which the conduit passes through the one or more slots.
21. The device of claim 20 additionally comprising one or more externally accessible flow rate control sticks (1002) which pass through one or more of the slots and which comprise a tapering wedge (1004) in the region of the stick which passes through the slot and which are moveable in a vertical direction to open or constrict the slot.
22. The device of claim 20 additionally comprising a foam cushion (1014) attached to the storage container and one or more flow rate control sticks (1002), wherein the foam cushion is positioned over the one or more holes and the flow rate control stick has a wedge (1012) at a lower end in contact with the foam cushion, whereby as the rate control stick slides from top to bottom, the foam cushion is either uncompressed in which case liquid may flow through the material, it is compressed over a single hole, in which case the flow from that hole is restricted, or it is compressed over two holes in which case the flow from the storage container is severely restricted.
23. The device of claim 20 additionally comprising a foam cushion (1014) and one or more flow rate control sticks (1002), wherein the flow rate control stick has a wedge (1012) at a lower end and the foam cushion is attached to the wedge and is positioned over the one or more holes, whereby as the rate control stick slides from top to bottom, the foam cushion is either over none of the holes in which case liquid may flow, it is over a single hole, in which case the flow from that hole is restricted, or it is over two holes in which case the flow from the storage container is severely restricted.
24. The device of claim 23 additionally comprising closure flaps (1016) over the holes, and as the rate control stick slides from top to bottom, the foam cushion is either over none of the holes in which case liquid may flow, it is over a single hole and closes the flap over that hole, in which case the flow from that hole is restricted, or it is over two holes in which case both flaps are closed and the flow from the storage container is severely restricted.
25. The device of claim 20 in which the conduit is supported by an upper surface of the flange.
26. The device of claim 25 in which a plant container (52) is supported by the flange, and the conduit is located between the flange and the plant container.
27. The device of claim 26 in which the conduit is comprised of several parts, in which one part is located between the holding tray and passes through a slot in the flange and another part is located on top of the flange and is located between a slot and the matrix.
28. The device of claim 25 comprising multiple conduits arranged radially around the flange, each conduit located between the flange and multiple plant containers.
29. The device of claims 1 or 20 to 28 in which the conduit is a capillary wick.
30. The device of claim 29 in which the capillary wick is enclosed in a pipe.
31. The device of claim 29 in which the capillary wick is enclosed in plastic film or covered by a piece of impermeable material.
32. The device of claim 1 in which the conduit is a pipe.
33. The device of claim 1 comprising a capillary wick (302) passing through one of said one or more holes.
34. The device of claim 1 in which the storage container and the holding tray are integrated into a single unit.
35. The device of claim 1 or 17 in which the storage container and the flange tray are integrated into a single unit.
36. A self-acting watering device for watering a plant-supporting matrix comprising two or more devices of claim 1, wherein the storage container of each device is connected to an extension container (60) via a liquid line (50) which connects the two containers at a point near a base of each container and an air line (53) which connects the two containers at a point near a top of each container.
37. The device of claim 36 additionally comprising an isolating valve (62) on the liquid line.
38. The device of claims 36 or 37 additionally comprising an isolating valve (65) on the airline.
39. A self-acting watering device for watering a plant-supporting matrix comprising a planter (33) having one or more holes (23) for admitting air into a base region of the planter, the device of claim 20 located in the base of the planter in which the flange extends to walls of the planter and in which there is a small gap between the rim of the holding tray and an underside of the flange, wherein the plant supporting matrix is located on top of the flange.
40. A storage container for use with the device of claim 1 characterised by said container having one or more holes (11, 15) in a basal region.
41. An extension tube for use with the container of claims 1 or 40 having at one end a sealable opening and at the other end having 0-rings (4) 50 that it plugs into the sealable opening of the container, whereby the volume of the container is increased.
42. An extension tank for use with the container of claims 1 or 40 having a liquid line (50) which connects the two containers at a point near a base of each storage container and an air iine (53) which connects the two containers at a point near a top of each container.
43. A flange for use with the device of claim 1 or 40 which attaches to the container and has one or more slots through which the conduit is able to pass.
44. A rate control stick for use with the device of claim 20 which comprises a tapering wedge (1004) in the region of the stick which passes through the slot and which are moveable in a vertical direction to open or constrict the slot.
45. The rate control stick of claim 44 additionally comprising a wedge (1012) at a lower end.
46. The device of claim 1 having a single hole and additionally comprising a vent pipe (104) forming a direct air connection between the holding tray and the top of the container.
47. A kit of parts for assembling the device of claim 1 comprising a holding tray and a container having a basal end located in the holding tray; characterised by the container having one or more holes in a basal region, said one or more holes being below a rim of the holding tray when the container is located therein.
48. The kit of claim 47 additionally comprising a flange.
49. The kit of claim 48 in which the flange extends beyond a rim of the holding tray.
50. A kit of parts for assembling the device of claim 1 comprising a container having a basal end characterised by the container having one or more holes in a basal region and a flange.
51. The kit of claims 47 or 50 in which the flange has one or more slots.
52. The kit of claim 51 additionally comprising a conduit able to pass through the one or more slots in the flange.