WO2001023065A1

WO2001023065A1 - Chemical feeder

Info

Publication number: WO2001023065A1
Application number: PCT/US2000/026433
Authority: WO
Inventors: David W. Blanchette; Christopher M. Zetena; Lorena C. O'neill
Original assignee: Arch Chemicals, Inc.
Priority date: 1999-09-28
Filing date: 2000-09-27
Publication date: 2001-04-05
Also published as: AU7617200A

Abstract

A device (34) for feeding a chemical into a water flow. A housing (100) has an interior with an inlet (44) to the housing admitting the flow and an outlet (122) which includes an outlet conduit (38, 136, 134, 142). The outlet conduit has an inlet port having (140) a user-adjustable elevation. The elevation determines a steady state elevation of the water surface within the housing interior. A foraminate member (188) has at least a portion positioned to be immersed in the water in the housing interior and contains a solid water treatment chemical (212) in contact with the water. The steady state elevation controls the rate of introduction of the chemical from the solid treatment chemical into the flow. The foraminate member is advantageously a basket portion of a water chemical treatment cartridge (174) which also includes a body portion comprising a sidewall (180), a top (182), and a mounting flange (184) for securing the cartridge to a receptacle area (170) on the feeder.

Description

CHEMICAL FEEDER

This invention relates to water treatment, and more particularly to feeders for introducing treatment chemicals into a recirculating water stream from a swimming pool or the like.

If untreated, swimming pool water provides an hospitable forum for the growth of bacteria, algae, and other undesirable and potentially unhealthful organisms. It, accordingly, has become common practice to treat pool water on both periodic and continuous bases with treatment chemicals to kill/control such organisms.

Such treatment is typically undertaken via the introduction of chlorine into the pool water at levels effective to kill or control the unwanted organisms. The chlorine source may be in liquid form or may be in a solid form which is then dissolved in the pool water. Among solid sources of chlorine are calcium hypochlorite (cal hypo), dichloroisocyanuric acid (dichlor), and trichloroisocyanuric acid (trichlor).

A variety of feeders exist to deliver chlorine from solid chemical tablets and the like. It is known to utilize a floating erosion dispenser, also known as a "floater" or "feeder", to provide a continuous release of the chemical. The floater contains the solid chemical and provides a controlled exposure of the chemical to the pool water which in turn controls the speed with which the water erodes the solid chemical to introduce chlorine to the pool water. Exemplary floaters are disclosed in U.S. Patent No. 4,917,868 and U.S. Design Patent Nos. 297,857 and 309,493. It is also known to pump pool water through an external feeder which may be incorporated in a circulation system that also provides filtering of the pool water. Among such systems are intermittent spray systems, erosion systems, and partial periodic immersion systems. Examples of such systems are shown in U.S. Patent Nos. 5,932,093, 5,928,608, 5,441,711, 5,427,748, 5,419,355, 5,384,102, 5,133,381, and 4,208,376, and U.S. Reissue Patent No. 33,861. As additional background, U.S. Patent Nos. 5,112,521 and 5,004,549 disclose various solid calcium hypochlorite compositions.

Accordingly, one aspect of the invention is directed to a device for feeding a water treatment chemical into a water flow. The device includes a housing having an interior with an inlet to the housing admitting the water flow and an outlet for evacuating the water flow which contains an outlet conduit. The outlet conduit has an inlet port having a user-adjustable elevation and has an outlet port. The elevation determines a steady state elevation of the water surface within the housing interior. A foraminate member has at least a portion positioned to be immersed in the water in the housing interior and contains a solid chemical in contact with the water. The steady state elevation controls the rate of introduction of the treatment chemical from the solid chemical into the flow.

Another aspect of the present invention is directed to a method for introducing a treatment chemical into a body of water at a controlled rate. A feeder is provided having an inlet and an outlet, and containing a solid chemical. A flow of water is directed from the body to enter the feeder through the inlet and exit through the outlet to return to the body so that a portion of the solid chemical is immersed below a surface of the water in the flow. An outlet conduit, extending upstream into the feeder from the outlet is adjusted so as to alter an elevation of an inlet port to the outlet conduit. The elevation determines a steady state elevation of the water surface and controls the rate of introduction of treatment chemical from the solid chemical into the flow and thereby into the body. The step of directing the flow may include applying a partial vacuum to the feeder outlet.

Another aspect of the present invention is directed to a water chemical treatment cartridge for installation on a feeder. The cartridge has a body including a sidewall, a top, and a flange. With the cartridge installed on the feeder, the flange has an upper surface portion in engagement with a locking ring and a lower surface portion in engagement with a receptacle area on the feeder. A foraminate member is secured proximate a lower end of the body. A stack of solid chemical tablets extends from a lower end within the foraminate member to an upper end within the body so that water within the feeder can communicate with the tablets proximate the lower end of the stack through the foraminate member and dissolve the treatment chemical from the tablets. As the tablets are dissolved, the remaining tablets in the stack can descend to maintain the introduction of treatment chemical to the water.

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

FIG. 1 is a partially schematic depiction of an exemplary pool circulation system including a feeder according to principles of the invention.

FIG. 2 is a partially schematic depiction of an exemplary pool circulation system with the feeder connected in an alternate fashion.

FIG. 3 is a side view of the feeder of FIGs. 1 and 2. FIG. 4 is a top view of the feeder of FIG. 3. FIG. 5 is a longitudinal cross-sectional view of the feeder of FIG. 3, take along line 3-3. FIG. 6 is a downstream end view of an outlet conduit assembly. FIG. 7 is a longitudinal cross-sectional view of the outlet conduit assembly of FIG. 6, taken along line 6-6. FIG. 8 is an exploded view of the outlet conduit assembly of FIG. 6.

FIG. 9 is a longitudinal cross-sectional view of the feeder of FIG. 5 in a maximum water height condition.

FIG. 10 is a partially exploded perspective view of the feeder of FIG. 5. FIG. 11 is an exploded perspective view of a cartridge for use in the feeder of FIG. 5. FIG. 12 is a cross-sectional view of the cartridge of FIG. 11.

FIG. 13 is a cross-sectional view of the feeder of FIG. 3, taken along line 13-13. Like reference numbers and designations in the various drawings indicate like elements. FIG. 1 shows a pool 20 containing a body 22 of pool water and associated with a circulation system 24. The circulation system has a pool outlet conduit 26 drawing water from the pool and a pool return conduit 28 returning water to the pool. Flow through these conduits is induced by a pump 30 with a low pressure (suction) side toward the pool outlet conduit 26 and a high pressure side toward the pool return conduit 28. Downstream of the pump, a system filter 32 may be provided to filter debris and the like from water flowing from the pump. Therefore, the primary recirculating flow path from/to the body 22 includes the pool outlet conduit 26, pump 30, filter 32, and pool return conduit 28. A secondary flow path is formed as a diversion of water from the primary flow path through a pool chemical feeder 34. The feeder 34 introduces a desired treatment chemical to the water flowing in the secondary flow path and, therefrom, to the primary flow path and thus to the pool water body 22. In the secondary recirculating flow path, a feeder inlet conduit 36 has an upstream end joining the return conduit 28 at a tee junction 38. A valve 40 (e.g., a user-actuated valve such as a ball valve) is located within the conduit 36 to selectively block and unblock flow through that conduit. A downstream end of the conduit 36 connects to the feeder 34 via a flow restrictor or regulator 42 at a feeder inlet port 44. The flow regulator 42 serves to maintain the volume/mass flow rate of water at substantially a given value despite variations in pressure differential across the regulator. An exemplary regulator is of the rubber diaphragm type, such as the VERNAFLOW, part number VL 3007-113, available from Vernay Laboratories, Inc. of Yellow Springs, Ohio. The exemplary regulator has a rating of 0.75 gallons per minute (gpm) (0.047 liters per second). With such a regulator, typical operational flow rates will be between 0.5 and 0.75 gpm (0.0315 and 0.047 liters per second).

At a feeder outlet port 46 at the downstream end of the feeder there is a feeder return conduit 48. To draw water through the feeder, the conduit 48 is subjected to a lower pressure than the conduit 36. In this exemplary embodiment, the downstream end of the conduit 48 is coupled to a vacuum pump 50 formed as a flow restriction such as a venturi having a venturi inlet flow through a venturi inlet conduit 52 and a venturi outlet flow through a venturi outlet conduit 54. The venturi inlet and outlet conduits respectively join the return conduit 28 at tee junctions 56 and 58. In the conduit 28, between the tee junctions 56 and 58, a valve 60 (e.g., a ball valve) may be utilized to restrict or block direct communication through the conduit 28 between those junctions 56 and 58. Such blockage induces flow through the vacuum pump 50 wherein the venturi effect will draw water along the secondary flow path through the conduit 48. In this event, the conduits 52 and 54 and the pump 50 form a portion of the primary flow path. Also, in the conduit 48, a valve 61 (e.g., a ball valve) may be utilized to restrict or block flow through that conduit.

The feeder 34 may also be provided with a pressure relief port 62 which receives the leg of a tee 64. One arm of the tee 64 is connected to the downstream end of a vacuum relief valve 66 (the upstream end thereof being exposed to atmosphere). The other end of the tee is connected to the upstream end of a positive pressure relief valve 68 (the downstream end thereof being coupled by a conduit to appropriate drainage which may involve return to the body 22). If the pressure within the feeder drops below a minimum threshold value, the valve 66 opens, admitting air to the feeder and preventing further pressure decrease and damage therefrom. If the pressure within the feeder exceeds a maximum threshold pressure, the valve 68 opens allowing water to be expelled therethrough and relieve such pressure. Exemplary valves 66 and 68 are available from Smart Products, Inc. of San Jose, California as check valve model 312. The valve 66 preferably opens at a pressure of about negative (2-3) psig (14-21 kPa) while the valve 68 preferably opens at a pressure of about 15 psig (10 kPa).

The feeder may also be provided with a drainage port 70 to drain the feeder during servicing. The drainage port may be connected to a drainage conduit 72 in which a drainage valve 74 (e.g., a ball valve) is located. The drainage conduit may simply terminate downstream of the drainage valve or may be directed for disposal storage or reuse.

An alternate circulation system 24' is shown in FIG. 2. The same basic feeder 34 may be utilized. In this system, the secondary flow path includes a feeder inlet conduit 36' and a feeder return conduit 48' respectively coupled to the primary flow path at downstream and upstream sides of the pump 30. The conduit 36' is coupled to the pool return conduit 28' via a tee 38' and carries a valve 40' (e.g., a ball valve). The conduit 48' connects to the pool outlet conduit 26' via a tee 59 and carries a valve 61 (e.g., a ball valve). In this configuration, the pressure differential across the feeder is supplied directly by the pump 30. Myriad other configurations could be utilized.

FIGs. 3-5 show further details of a preferred embodiment of the feeder 34. The feeder has a one-piece rotomolded body or housing 100 having an upper portion 102 A and a lower portion 102B. The preferred plastic material for the housing is a high density polyethylene (HDPE) such as sold under the trademark HRP-111, by Mobil Polyethylene of Edison, New Jersey. The lower portion 102B includes molded feet 104 (FIGs. 4 and 5) (there being four in the exemplary embodiment) for supporting the feeder atop the ground 900 or other support surface.

The lower housing portion 102B (FIG. 5) further is molded with a pair of upwardly projecting, generally conical posts 106, the tips of which engage mating features of the upper portion 102 A. The posts serve to support the upper portion against the force of ambient air when a vacuum is applied to the feeder. At the upstream end 108 A of the housing 100, the inlet port 44 is provided with an internally threaded fitting 112 for coupling the feeder to the feeder inlet conduit (e.g., 36; 36' of FIGS. 1 and 2) via the flow regulator 42 (of FIGS. 1 and 2). In the exemplary embodiment, therefore, inlet port 44 is the inlet port for the feeder 34 in general and the housing 100 in particular. The flow regulator 42 may, optionally, be more highly integrated with the feeder 34 and its housing 100 or may be located elsewhere in the secondary flow path. The flow regulator 42, however, is preferably located proximate or upstream of the feeder/housing inlet port 44. The fitting 112 may be formed of a plastic such as low density polyethylene (LDPE) via a process such as injection molding and secured to/integrated with the housing 100 such as by spin welding. A fitting 114 may similarly be secured to the pressure relief port 62 to establish connection with the relief valves (e.g., 66, 68 of FIGS. 1 and 2). In the exemplary embodiment, therefore, the pressure relief port 62 generally designates a port in the feeder 34 in general and housing 100 in particular. The relief valves may, optionally, be more highly integrated with the feeder 34 and the housing 100. Relative to the inlet port 44 the pressure relief port 62 is located high on the housing to preferentially vent gas if a gas/water mixture within the feeder is at an excessive pressure. At the downstream end 108B of the housing 100, the drainage port 70 may receive an internally threaded fitting 118 in similar fashion to the inlet port. The drainage port 70 is preferably located relatively low to enhance the degree of drainage which may be achieved. Above the drainage port 70, a housing outlet fitting 120 may be secured to a housing outlet port 122 in similar fashion. The fitting 120 interfaces with an outlet conduit assembly 124, the downstream end of which provides the feeder outlet port 46.

FIG. 6 and its sectional and exploded views of FIGs. 7 and 8 show further details of the outlet conduit assembly 124. FIGs. 7 and 8 show a fixed fitting-engaging member 126 which has an externally threaded upstream portion 128 for engaging the internally threaded body outlet fitting 120. A downstream portion 130 is externally threaded for engagement to an internally threaded contoured collar 132. Extending along a body outlet axis 902 through the member 126 is a pipe 134. The upstream end of the pipe 134 is secured within the downstream end of an elbow 136 such as by threaded engagement or cementing. The upstream end of the elbow 136 receives the downstream end of a pipe 138 extending transversely to the axis 902. The upstream end 140 of the pipe 138 is open, defining an inlet port to the outlet conduit assembly. The downstream end of the pipe 134 is secured within an outlet fitting 142 such as by cementing or threaded engagement. At its upstream end, the outlet fitting 142 has an outwardly projecting radial flange 144 which is clamped between a radially inward projecting flange 146 of the collar 132 and a downstream end of the member 126, engaging the latter via an O-ring 148 (e.g., formed of ethylene-polypropylene (EPDM) such as part no. 222-40 EP of Apple Rubber Products, Inc. of Lancaster, New York) riding in a channel in the member 126. The clamping engagement permits the fitting 142 as well as the elbow and pipes to rotate about the axis 902 but otherwise restricts their movement. The downstream end of the outlet fitting 142 defines the downstream end of the outlet conduit assembly 124 and, therefore, the feeder outlet port 146 concentric with the axis 902. An indicator member 150 is secured to the outlet fitting 142 to rotate therewith about the axis 902. In the exemplary embodiment, the indicator 150, best seen in FIG. 8, has a hexagonal channel which mates with a hexagonal external feature of the outlet fitting. The indicator 150 includes a hub 152 surrounding the hexagonal feature, an arm 154 extending longitudinally upstream from a periphery of the hub 152 to a radially-extending indicator tip 156. The member 126, collar 132, fitting 142, and indicator member 150 may be custom molded of polyvinyl chloride (PVC), such as is available from The Geon Company of Avon Lake, Ohio under the trademark M3000. The pipes 134 and 138 and elbow 136 may be Schedule 40 stock PVC products (e.g., V* inch (1.9 cm) ID pipe). When installed in the feeder, the outlet conduit assembly is rotatable about the axis 902 through a plurality of orientations. In one orientation (shown in FIG. 5) the pipe 138 is directed vertically with its upstream end 140 facing directly downward at a minimum possible height within the feeder body. By gripping and turning the indicator member 150, a user may rotate the non-fixed portions of the outlet conduit assembly about the axis 902. When rotated 180° relative to the position of FIG. 5, the upstream end 140 of the pipe 138 reaches a maximum possible height (FIG. 9). Suction applied to the feeder outlet port 46 at the downstream end of the outlet fitting 142 draws water through the feeder from the feeder inlet port 44. The height of the pipe end 140 will determine the level of the surface of the water within the feeder. A minimum level 904 for the surface of the water within the feeder is shown in FIG. 5 and a maximum level 904' is shown in FIG. 9. An exemplary span between minimum and maximum levels is approximately 6 inches (15 cm). Preferably such span is at least about 1 inch (2.5 cm). Although, in the exemplary embodiment, the outlet conduit is formed as an outlet conduit assembly 124, other constructions, such as a one-piece molded conduit, may be provided. Also, adjustment mechanisms other than the exemplary rotation about the axis 902 may be utilized.

FIG. 10 shows molded-in-place indicia 160 on the exterior surface of the housing 100 at the downstream end thereof. As the indicator is rotated through its possible orientations, the indicator tip 156 is directed amongst the indicia 160 to sequentially register with each of the indicia 160 to indicate that the height of the water surface corresponds to the particular indicia. The exemplary indicia are a scale of 1 to 9, arrayed from 9:00 to 3:00 as on a clock. The indicator tip is offset by 90° from the pipe end 140 so that when the indicator tip is in the 9:00 position the pipe end is at its minimum height and as the indicator tip is rotated toward the 3:00 position, the pipe end is raised toward its maximum height. Each of the feet may be provided with a screw 105 (FIG. 10) to secure the feeder to the support surface. The upper portion 102 A of the housing 100 includes a plurality of receptacles 170, each of which includes a central aperture 172. In the exemplary embodiment there are three such receptacles arrayed from upstream to downstream. Each receptacle may receive a water treatment chemical cartridge 174 or a cover 176. A cover 176 is used on each receptacle 170 which does not receive a cartridge 174. Normally, at least one cartridge 174 will be present during feeder operation. The cartridge 174 or the cover 176 seals the associated aperture 172 allowing partial vacuum conditions to be maintained within the feeder head space above the water surface. FIGs. 9 and 10 show a pair of cartridges 174 in the two upstream receptacles and a cover 176 in the downstream receptacle. Each cartridge 174 includes a body having a slightly frustoconical upper sidewall portion 180 capped by a nearly hemispherical dome 182. A flange 184 extends radially outward from the lower end of the upper sidewall portion 180 and a nearly cylindrical lower sidewall portion 186 depends from the flange. At the lower end of the lower sidewall portion 186 a foraminate basket 188 is secured to the body such as by spin welding to form a lower portion of the cartridge. The exemplary basket 188 is molded with a plurality of apertures of sufficient individual and aggregate dimensions to permit communication of dissolved treatment chemical through the basket as described below while being small enough to retain the tablets (in their original or a substantially diminished size) within the basket. Other foraminate members (e.g., mesh and perforated elements) may alternatively be utilized. Exemplary illustrated apertures are approximately 0.125 inch (3 mm) high and from about 0.375 inch (1.0 cm) to 1.7 inch (4.3 cm) in circumferential extent depending on their vertical position.

FIGs. 11-13 show further details of a cartridge 174. The exploded view of FIG. 1 1 shows that the body may be filled with solid chemical tablets 200, whereupon the basket may be secured to the body such as by spin welding. The basket bears an externally threaded shoulder 202 which is engagable with an internally threaded mouth 204 of a disposable cap or cover 206. When the cap is screwed onto the basket, the tablets 200 are substantially sealed within the cartridge in a pre-use condition. As a child resistance feature, the cap and basket may respectively be provided with interfitting features 208 and 210 which prevent unscrewing of the cap once in place unless sufficient inward radial pressure is applied to the feature 208 so as to allow it to pass by the feature 210 permitting unscrewing of the cap. A variety of different child-resistant features may be utilized. When the assembled cartridge is righted, the tablets 200 extend in a stack 212 (FIG. 12) from a stack bottom 214 to a stack top 216. The cap may be unscrewed and discarded to permit installation of the cartridge on the feeder. Exemplary tablets may be formed of calcium hypochlorite (blended with 2.5% lime by weight and 0.5% scale inhibitor (U.S. Pat. No. 5,004,549)) and are disk-shaped, having an approximate size of 1 inch (2.5 cm) in diameter and 5/8 inch (1.6 cm) thick. In one preferred embodiment, the tablet stack may have a total mass of about 10 lbs (4.5 kg). The cartridge body, basket and cap may be formed of injection molded HDPE such as is available from Mobil Polyethylene under the trademark HMA-045. The cartridge body and feeder housing each preferably have sufficient strength to operate under an internal pressure of -3 psig (-20 kPa) without substantial collapse. FIG. 13 shows details of a cartridge installed in the feeder. For ease of illustration, the tablet stack is not shown. Circumscribing the aperture 172, the receptacle includes a pair of inboard and outboard annular upward facing channels 220 and 222. Outboard of the channel 222, the receptacle has an externally-threaded shoulder 224. A screw-on locking ring 226 has a lower internally threaded mouth portion 228 which may be engaged to the externally threaded portion 224 of the receptacle. An inboard, downward facing, radially-extending surface 230 faces the channels 220 and 222 and may clamp the flange 184 between itself and the receptacle.

The flange 184 includes a downwardly -projecting annular keying feature 232 positioned and dimensioned to be received by the inboard channel 220. The underside of the flange 184, outboard of the keying feature 232 provides a seat 234 which compresses an O-ring 236 (e.g., of EPDM such as Apple Rubber Products, Inc. part no. 446-70EP) within the outboard channel 222 to provide a seal between the cartridge and the receptacle. The keying feature 232 is provided with a right channel-like cross section. Structural rib portions 237 of the flange 184 may extend radially across and over the channel and other structural rib portions 238 may extend circumferentially to provide the flange with strength. The position and shape of the keying feature 232 correspond to those of the inboard channel 220.

It may be desired to only allow certain cartridges to be permitted to be used in certain feeders or certain receptacles thereof. In such a situation, the feeders/receptacles may be provided having keying features and inboard channels with different radial positions, thicknesses, depths, or other properties complementary to the particular cartridges intended for use with such feeders/receptacles. The channel-like construction of the keying feature 232 provides that if the keying feature is removed such as by cutting, grinding, or the like, there will be holes in the underside of the flange 184 inboard of the seat 234 and outboard of a hub portion of the flange. This may cause a partial or total severance of the outboard portion from the inboard portion. It may also allow air to be drawn through such holes, hindering operation of the feeder. Thus removal of the keying feature will prevent effective use (or misuse) of the cartridge. The use of the exemplary keying feature greatly reduces the costs of tooling changes associated with providing different, non-interchangeable cartridges.

In the illustrated embodiment, at the minimum level, the water surface is below the lowermost extremities of the baskets so that the chemical tablets in the cartridges are not contacted by the water and thus do not introduce substantial amounts of treatment chemicals to the water. As the level is increased, the water will begin to contact the tablets. From such a minimum contact level upward, the amount of tablets contacted by the water will increase as will the rate of chemical introduction to the water. In alternate embodiments, all levels may involve contact with the tablets. The presence of the flow regulator 42 is advantageous since fluctuations in flow rate will effect the rate of chemical introduction for a given indicator setting. Such fluctuations are thus advantageously minimized.

As those tablets contacted by the water dissolve, additional tablets descend into contact with the water. Ultimately, the top of the tablet stack will descend into the water and, sometime thereafter, the last tablets will dissolve so that the cartridge must be replaced.

When it is desired to replace a cartridge or otherwise service the feeder, a user will close the ball valves 40, 61 or 40', 61' to isolate the feeder from the primary flow path and open the drain valve 74 which releases the vacuum within the feeder, allowing accumulated water to drain (preferably at least to a level below the lower extremities of the baskets). To help facilitate drainage, the interior surface of the lower housing portion 102B has a general downstream declination (e.g., on the order of about 1°). This declination also may help encourage flow through the feeder and prevent sediment buildup during operation. The user then applies a removal tool 250 (FIG. 10) to the locking ring 226 associated with the cartridge 174 or cap 176 to be removed. The tool 250 may be molded of a robust material such as polycarbonate as is available from GE Plastics, Pittsfield, MA under the trademark LEXAN 101. The tool 250 includes a ring portion 252 and a handle portion 254 extending radially outward. Depending from the underside of the ring portion 252 are a plurality of projections 256 (of which a single projection is shown in FIG. 10) complementary to a plurality of recesses 258 in the locking ring 226. When the tool is placed over the locking ring and the projections and recesses interengage, rotation of the tool produces rotation of the locking ring to either install/tighten or remove/loosen the locking ring. The tool is thus used to unscrew and remove the locking ring whereupon the cartridge or cap in question may be removed. Another cartridge may then be installed in place of the cartridge or cap and the locking ring replaced and tightened with the tool to secure the cartridge in place. Thereafter, the user will close the drain valve 74 and open the valves 40, 61 or 40', 61' to reestablish flow through the feeder.

By providing the option of multiple cartridges in addition to the water level control, a wide range of feed rates is possible. In an exemplary embodiment, one cartridge and a relatively low water level could handle the load of a commercial spa (e.g., about 500-1,000 gallons (1.9-3.8 m³)), with three cartridges and a higher water level being utilized on a large pool (e.g., in the vicinity of 70,000 gallons (265 m³)). Depending on the desired feed rate, the exemplary cartridges would have an approximate life span of between about 1.5 days and about one month. The use of disposable cartridges helps protect users from contact with the chemical tablets and, also, improves performance in that the baskets, forming a part of the cartridge, will be replaced long before deposits can plug their openings and, thereby, affect performance. The vacuum operation, combined with the various safety valves, prevents buildup of gas (e.g., air and chloramines) within the feeder. One or more embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, the feeder could be used with tablets or other bodies of trichlor, dichlor, and/or bromine. An electronic control and actuator could be provided to automate the water height adjustment. The feeder could be utilized in a non-recirculating flow such as when using a flow of water into a surge tank to deliver treatment chemicals to that tank. The principles of the invention may be applied to feeders configured to utilize but a single cartridge or multiple cartridges or to feeders which do not use replaceable cartridges at all.

Claims

CLAIMS 1. A device (34) for feeding a water treatment chemical into a water flow comprising: a housing ( 100) having an interior; an inlet (44) to the housing admitting the flow of water to the housing interior; an outlet ( 122) from the housing; and at least one foraminate member (188) having at least a portion positioned to be immersed in the water in the housing interior as such water flows from the inlet to the outlet and containing a solid water treatment chemical (212) in contact with such water, characterized in that the outlet contains an outlet conduit (138, 136, 134, 142) evacuating the flow of water from the housing interior, the outlet conduit having an inlet port (140) and an outlet port (46), the inlet port having a user-adjustable elevation, said elevation determining a steady state elevation of a water surface in the housing interior, the steady state elevation controlling the rate of introduction of the water treatment chemical from the solid water treatment chemical into said flow.

2. The device of claim 1 further characterized by: a flow restrictor (42) proximate or upstream of the inlet and serving to maintain a flow rate through the flow restrictor despite variances in pressure drop across the flow restrictor.

3. The device of claim 1 further characterized in that the user adjustment is achieved by a rotation of the outlet conduit about an outlet axis (902) which is concentric with a downstream end of the outlet conduit.

4. The device of any of claims 1 , 2, or 3 further characterized in that the housing bears a plurality of water level indicia (160) about said outlet axis and the outlet conduit is securely coupled to an indicator member (150) which when rotated with said outlet conduit is directed amongst said indicia so that the indicia provide the user with an indication of the steady state elevation associated with the orientation of the indicator member.

5. The device of any of claims 1, 2, or 3 further characterized in that a range of said user adjustable elevation is at least 2.5 cm.

6. The device of claim 5 further characterized in that said steady state elevation is adjustable: from a minimum level (904) below the foraminate member; to a second level at which the water in the housing interior initially contacts the solid chemical; through a continuum of levels in which greater amounts of said solid chemical is in contact with the water; to a maximum level (904').

7. The device of any of claims 1, 2, or 3 further characterized in that the foraminate member (188) forms a lower portion of a cartridge (174) and the housing has a top portion (102A) having a receptacle (170) for removably receiving the cartridge.

8. The device of claim 7 having at least two such foraminate members (188), receptacles (170) and cartridges (174).

9. The device of claim 7 further characterized by two additional receptacles (170) and two receptacle cover members (176) which have: an installed condition secured by an associated locking ring (226) to the associated receptacle so as to close such receptacle; and a removed condition in which a chemical-containing cartridge (174) may be installed on such receptacle and secured thereto by such locking ring.

10. The device of any of claims 1, 2, or 3 in combination with a pump (50) downstream of the outlet (122) and acting to reduce an absolute pressure within a headspace of the feeder below ambient atmospheric pressure.

11. The device of claim 10 further characterized in that said pressure is reduced to between 7 and 14 kPa below atmospheric pressure.

12. The device of claim 11 further characterized in that said pump (50) comprises a restriction in a conduit in a primary recirculating flow path from/to a swimming pool or a spa (20) and said water flow is along a secondary flow path from/to the primary flow path.

13. The device of any of claims 1, 2, or 3 further characterized in that the housing has a bottom portion (102B) which, along a majority of an internal surface thereof, has a downward slope from the inlet to the outlet.

14. A method for introducing a treatment chemical into a body (22) of water at a controlled rate comprising: providing a feeder (34) having an inlet (44), an outlet (46), and containing a solid chemical (212); and causing a flow of water from the body to enter the feeder through the inlet and exit through the outlet to return to the body so that a portion of the solid chemical is immersed below a surface of the water in the flow; characterized by adjusting an outlet conduit (138, 136, 134, 142), extending upstream into the feeder from said outlet, so as to alter an elevation of an inlet port ( 140) to said outlet conduit, said elevation determining a steady state elevation of the water surface, said steady state elevation controlling the rate of introduction of treatment chemical from said solid chemical into said flow and, thereby, into said body.

15. The method of claim 14 further characterized in that: the step of causing a flow comprises applying a partial vacuum to the feeder outlet.

16. A water treatment chemical cartridge (174) for installation on a feeder (34) comprising: a body portion comprising a sidewall (180), a top (182), and a flange (184) which, with the cartridge installed on the feeder, has an upper surface portion in engagement with a locking ring (226) and a lower surface portion in engagement with a receptacle area (170) on the feeder; a foraminate member (188) secured proximate a lower end of the body; and a stack (212) of solid chemical tablets (200) extending from a lower end (214) within the foraminate member to an upper end (216) within the body so that water within the feeder can communicate with the tablets proximate the lower end of the stack through the foraminate member and dissolve said treatment chemical from the tablets and, as the tablets are dissolved, the remaining tablets of the stack can descend to maintain the introduction of the treatment chemical to the water.

17. The cartridge of claim 16 further characterized by a removable cover (206): secured to the body via threaded engagement and enclosing the foraminate member

(188) when the cartridge is in a pre-use condition; and removeable from the body by unthreading to permit the cartridge to be installed on the feeder for introducing the treatment chemical from the tablets to the water.

18. The cartridge of claim 16 further characterized in that the body has sufficient strength to operate under an internal pressure of -3 psig (-20 kPa).

19. The cartridge of claim 18 further characterized in that the flange ( 184) comprises: an annular seat (234) for engaging an elastomeric o-ring seal (236) on the receptacle; and a keying portion radially (232) inboard of the seat and protruding below the seat so that removal of the keying portion at least partially severs an outboard portion of the flange containing the seat from an inboard portion of the flange secured to the cartridge body.

20. The cartridge of claim 16 further characterized in that the foraminate member (188) is a molded plastic basket.