WO2013093944A2

WO2013093944A2 - Device for dosing chemicals

Info

Publication number: WO2013093944A2
Application number: PCT/IN2012/000840
Authority: WO
Inventors: Dilshad Ahmad; Rajshree PATIL; Shankar Kausley
Original assignee: Tata Consultancy Services Limited
Priority date: 2011-12-22
Filing date: 2012-12-21
Publication date: 2013-06-27
Also published as: WO2013093944A3

Abstract

A dosing device (104) for dosing of chemicals in liquids is described. The dosing device (104) includes a valve unit (116) configured to control the flow of liquid entering the dosing device (104). The liquid from the valve unit (116) may be received by the liquid collection unit (120). The liquid collection unit (120) may be in fluid communication with the dosing unit (118). The dosing unit (118) includes a diffuser (222) to facilitate dosing of the chemical in the liquid flowing through the liquid collection unit (120).

Description

DEVICE FOR DOSING CHEMICALS TECHNICAL FIELD

[0001] The present subject matter relates, in general, to dosing of a chemical into a liquid and, in particular, to a device for dosing a chemical into water. BACKGROUND

[0002] Liquids, such as water are used as working fluids in various industrial processes as well as in various household applications, such as for drinking, cleaning, and bathing. These industrial processes and household applications usually require enhancing the quality of the liquid to achieve better results by, for example, adding chemicals. For instance, drinking water may be purified by adding various chemicals, such as chlorine, aluminum hydroxide, and magnesium oxide to make the water suitable for drinking. Similarly, chlorine may be added to water in swimming pools for disinfecting the water. In another example, chemicals, such as detergents are added in water to facilitate efficient washing of clothes, for example, in households or laundry industry. [0003] Further, in order to achieve a desired result, the concentration of a chemical added in the liquid may be controlled. Consistent and controlled dosing of chemicals in a liquid is thus of importance, both in the domestic as well as the industrial applications. Typically, the chemical is dosed as a liquid or as a powder with a suitable dispensing mechanism. The rate of dosing a chemical is generally large and the concentration of the chemical to be dosed in the liquid is controlled by varying the flow of liquid chemical or by varying amount of dry powder into the liquid. However, such mechanisms may not be suitable for cases where a small and precise amount of chemical is to be dosed.

SUMMARY

[0004] This summary is provided to introduce concepts related to a device for dosing of chemical in water, which is further described below in the detailed description. This summary is neither intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.

[0005] In one embodiment, a device for dosing of a chemical in a liquid is described. The dosing device includes a valve unit configured to control the flow of the liquid entering the dosing device. The liquid from the valve unit may be received by a liquid collection unit, which is in fluid communication with a dosing unit. The dosing unit includes a diffuser to facilitate dosing of the chemical in the liquid flowing through the liquid collection unit.

BRIEF DESCRIPTION OF DRAWINGS

[0006] The detailed description is provided with reference to the accompanying figures.

In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and components. [0007] Figure 1 illustrates an apparatus for dosing chemical into a liquid, according to an embodiment of the present subject matter.

[0008] Figure 2 illustrates various components of a d osing device o f the apparatus, according to an embodiment of the present subject matter.

[0009] Figure 3 illustrates a valve unit of the dosing device, according to an embodiment of the present subject matter.

[0010] Figure 4 illustrates a dosing unit of the dosing device, according to an embodiment of the present subject matter.

[0011] Figure 5 illustrates a liquid collection unit of the dosing device, according to an embodiment of the present subject matter. [0012] Figure 6 illustrates various components of a dosing device of the apparatus, according to another embodiment of the present subject matter.

[0013] Figure 7 illustrates a valve unit of the dosing device, according to an embodiment of the present subject matter.

[0014] Figure 8 illustrates a dosing unit of the dosing device, according to an embodiment of the present subject matter

[0015] Figure 9 illustrates a graph depicting performance of the dosing device, according to an embodiment of the present subject matter. DETAILED DESCRIPTION

[0016] Devices and methods for dosing a chemical in a liquid, such as water are described herein. Chemical dosing in a liquid is important in a number of household and industrial applications, such as water purification. Many household water purification devices use chemicals as disinfectants.

[0017] Various methods and devices have been employed to dose a chemical into a liquid. Typical dosing devices may comprise a tablet, closed in a replaceable cartridge, to slowly release the chemical in the liquid. The tablet may include different kinds of slowing agents to facilitate slow release of chemicals. Generally, over a period of time, these dosing devices may not be dose a precise amount of chemical in the liquid and their dosing rate may vary. Further, these devices may not be suitable for dosing chemicals in trace concentrations, such as 0.20 parts per million (ppm). Additionally, a dissolving surface of tablets may get altered over a period of time resulting in a changed concentration of the chemical in the liquid as otherwise required. [0018] Further, it may be useful for a user to know the spent or consumed life of a dosing unit, in order to ensure that a dosing device is not used after the exhaustion of the chemical to be dosed. Also, the flow of liquid may have to be terminated when a predefined life of the dosing device is reached to ensure that the dosing unit is not used upon the exhaustion of the chemical to be dosed. [0019] According to an embodiment of the present subject matter, a dosing device for dosing of a chemical in a liquid, such as water is described. The dosing device provides for controlled and precise dosing of the chemical in the liquid. For the ease of explanation, and not as a limitation, the explanation of the embodiments will be provided with respect to the chemical being a chlorine releasing compound, which is dosed in water. However, it will be understood that embodiments and implementations described herein can be used dosing of any suitable chemical in any liquid.

[0020] According to an implementation, the dosing device may include an inlet and an outlet. The inlet may be used for receiving water, which may be contaminated. Upon receiving the water, a dosing unit of the dosing device may release the chemical to be dosed into the water such that a predetermined concentration of the chemical is maintained in the water. The dosing unit may include a diffuser to provide for dosing of the chemical in a controlled manner. The diffuser may dose the chemical owing to a concentration gradient developed in a liquid collection unit having the liquid to be dosed. Further, the dosed water, i.e., water dosed with the chemical, may be received from an outlet of the dosing device.

[0021] Additionally, the dosing device may include an indicator indicating unused amount of the chemical, which may in turn indicate the spent or consumed life of the dosing unit. Further, it may be understood that the indicator may also be considered to be indicative of the amount of water passed through the dosing unit. Furthermore, when a predefined spent or consumed life of the dosing unit is reached, the flow of water through the dosing device may be automatically stopped. Such a provision ensures that upon exhaustion of the chemical, untreated water is not provided for consumption or further use.

[0022] Figure 1 illustrates a schematic block diagram representation of an apparatus 100 for dosing a chemical into a liquid, such as water, according to an embodiment of the present subject matter. In said embodiment, the apparatus 100 includes a source container 102 for storing the water that needs to be dosed with the chemical, a dosing device 104 for dosing the chemical in the water, and a collection container 106 for receiving the dosed water. In one implementation, the dosing device 104 may be connected to the source container 102 in a leak proof manner. The dosing device 104 provides controlled and precise dosing of the chemical into the water. [0023] In an example, water from any source, such as ground water and other surface water sources may be poured in to the source container 102 through a water inlet 108. The water from the source container 102 may then enter the dosing device 104 as shown by an arrow 1 10. In an embodiment, the dosing device 104 may be used to dose a predetermined amount of the chemical into the water. In an example, the chemical may be chlorine and the predetermined amount may be in the range of about 0.1 to 0.6 ppm of chlorine in the water. Further, the dosing device 104 may be configured to dose, such that a predetermined concentration, for example, on an average 0.20 ppm, of the chemical is maintained in the water.

[0024] In an embodiment, the dosing device 104 includes a valve unit 1 16, a dosing unit

1 18, and a liquid collection unit 120. The valve unit 1 16 may be configured to control the flow of water entering the dosing device 104. Further, the liquid collection unit 120 is configured to store and channelize the water, which has entered in the dosing device 104, so as to reduce the turbulence of the water. Furthermore, the dosing unit 1 18 of the dosing device 104 is configured to dose the water in the liquid collection 120, maintaining a predetermined concentration of the chemical.

[0025] Upon dosing, the dosed water may then flow into and get collected in the collection container 106 as shown by an arrow 1 12. In an embodiment, the collection container 106 is provided with an outlet, such as a tap 1 14, from where the dosed water may be drawn for consumption.

[0026] Figure 2 illustrates various components of the dosing device 104 according to an embodiment of the present subject matter. In implementation, the dosing device 104 includes the valve unit 1 16, the dosing unit 118, and the liquid collection unit 120. The valve unitl 16 includes a valve unit inlet 202. The valve unit inlet 202 is configured to receive the water from the source container 102. Further, the valve unit 1 16 includes a valve piston 204 attached to a link 206. In one implementation, the valve piston 204 and the link 206 are configured to move up and down in order to open and close the valve unit inlet 202 to control the flow of the water. Further, the valve piston 204 may move in the valve unit 1 16 in a leak proof manner to avoid leakage of the water. To avoid leakage, the valve piston 204 may be composed of a material that may be used for sealing purposes, for example, materials such as rubber, silicon rubber, neoprene, leather or any other suitable flexible material may be used. '

[0027] Based on the movement of the valve piston 204, water from the valve unit 1 16 may enter the liquid collection unit 120 via the valve unit outlet 208. The ¾quid collection unit 120 includes, for example, an auxiliary tube 226, a liquid chamber 228, and a channel 230. In one implementation, the liquid chamber 228 receives the water from the valve unit outlet 208 through the auxiliary tube 226. The flow of water through the auxiliary tube 226 helps in channelizing the water to lower the turbulence of the water. Further, the liquid chamber 228 may have a larger cross sectional area as compared to the auxiliary tube 226, which may also provide for reduction in turbulence. The reduced turbulence helps maintain a uniform level of the water inside the liquid chamber 228. The uniform level of the water in the liquid chamber 228 in turn ensures that a predetermined concentration of the chemical is maintained in the dosed water. [0028] Thus, the liquid chamber 228 may be in fluid communication with the dosing unit

1 18. Further, the water inside the liquid chamber 228 may be provided with a predetermined amount of the chemical by the dosing unit 118. In an example, the dosing unit 1 18 includes a plurality of chemical tablets 210-1 to 210-n, collectively referred to as chemical tablets 210. The chemical tablets 210 contain the chemicals to be dosed. In other examples, the dosing unit 1 18 may include a cartridge or a single tablet having the chemical to be dosed.

[0029] In an implementation, the chemical tablets 210 may be composed of a combination of halogen releasing components, additives, lubricants, and binders. Example of the additives include, but are not limited to, calcium sulphate, magnesium sulphate, calcium carbonate, magnesium carbonate, sodium persulphate, potassium phosphate dibasic calcium phosphate, aluminium sulphate, ferric sulphate, aluminium hydroxide, ferric hydroxide, adipic acid, boric acid, cellulose, starch, glucose, lactose, mannitol, sorbitol, and combinations thereof. Further, the additives may be added in the range of about 0 % to about 90 % by weight.

[0030] Examples of the binders include, but are not limited to, sucrose, lactose, starch, cellulose, microcrystalline cellulose, hydroxypropyl cellulose, sorbitol, mannitol, gelatin, ; polyvinylpyrrolidone (PVP), PVP K-30, polyethylene glycol (PEG), and combinations thereof.' Further, the binders may be added in the range of about 0 % to about 60 % by weight.

[0031] Additionally, the lubricants, in one example, may include talc, silica, sodium stearate, magnesium stearate, stearic acid, and combinations thereof. Further, the lubricants may be added in the range of about 0 % to about 60 % by weight.

[0032] Referring to Figure 2, the dosing unit 1 18 may include a tablet holder 212 to hold the lower most chemical tablet 210-n. The tablet holder 212 holds the lower most chemical tablet 210-n such that there is no gap in between the lower most chemical tablet 210-n and the tablet holder 212. In one implementation, the lower most tablet 210-n being kept on the tablet holder 212 avoids any leakage of the water through the interface and thus eliminates the possibility of dissolution of the chemical tablets 210 from their curved surfaces. Further, such a configuration also ensures that dissolution of the chemical tablets 210 is only from the bottom surface of the lower most chemical tablet 210-n.

[0033] In an example, to keep the chemical tablets 210 in their position in the tablet holder 212, a spring 214 may be provided. One end of the spring 214 may be coupled to¹ an indicator 216, while other end of the spring 214 may be restricted by a spring support 218. Further, the indicator 216 may be connected to the valve piston 204 by the link 206.

[0034] In one embodiment, as the lower most chemical tablet 210-n starts dissolving, the indicator 216, resting on the top most chemical tablet 210-1, moves down due to the force exerted by the spring 214. In one example, the number of tablets consumed may be indicative of the spent or the consumed life of the dosing unit 1 18. Further, as only a predetermined amount of the chemical is dissolved for a given amount of water, the indicator 216 may be used to indicate the spent life of the dosing unit 1 18, or in other words, the amount of water that has entered into the dosing unit 1 18. [0035] In an example, the valve unit 1 16 and the dosing unit 1 18 may be placed inside a casing 220. The casing 220 provides mechanical robustness to the dosing device 104. The casing 220 may be provided with a diffuser 222 in contact with a bottom surface of the lower-most chemical tablet 210-n. The chemical tablets 210 may be placed over the diffuser 222 with the help of the tablet holder 212 in a leak proof manner to avoid water seepage in to the casing 220, which in turn may ensure that the sides of the chemical tablets 210 do not dissolve. The diffuser 222 may be, for example, a permeable media, which may be composed of any inert porous material, such as woven or non- woven cloth or bed composed of felt, nylon, polypropylene, polyamide, and polyester fibers. The diffuser 222 on one side is in contact with the lower most chemical tablet 210-N and on other side is in contact with the water in the liquid chamber 228. The diffuser 222 may be capable of absorbing water and may control the rate of diffusion of the chemical from the chemical tablets 210 into the water. Further, it will be understood that any other component that provides for controlled movement of water under the effect of a concentration gradient may also be used. Furthermore, the diffuser 222 may be provided with a plurality of legs 224 so as to ensure a constant clearance below the diffuser 222. Owing to provision of the diffuser 222, which allows for dosing of the chemical into the water, small and precise amount of chemicals may be dosed in the water.

[0036] Thus, the chemical is mixed in the water by way of the diffuser 222 and the dosed water may come out of the liquid collection unit 120 through the channel 230. In an implementation, the dimension of the channel 230 may be selected in a way, so as to maintain a specific level and a specific rate of flow of the water thus maintaining a desired water level in the liquid chamber 228.

[0037] For the purpose of explanation and not as a limitation, the flow of water through the various components of the dosing device 104 may be understood with the following description. In operation, water to be dosed is received by the dosing device 104 via the valve unit inlet 202. The received water may come out by the valve unit outlet 208 and is received by the liquid collection unit 120. Water from the valve unit outlet 208 gets collected at the bottom of the liquid chamber 228 via the auxiliary tube 226 and forms a uniform layer. The water accumulated in the liquid chamber 228 progresses to the collection container 106 through the channel 230. As the water continues to enter the liquid chamber 228, the level of the water increases to come in contact with the diffuser 222. Consequently, the water seeping through the diffuser 222 reaches the top surface of the diffuser 222.

[0038] At this point, the lower most chemical tablet 210-n comes in contact with the water seeping through the diffuser 222 and starts dissolving from its bottom surface. This creates a high concentration of the chemical at an interface of the diffuser 222i and the lower most chemical tablet 210-n. In other words, water touching the interface of the diffuser 222 and the lower most chemical tablet 210-n, contains a high concentration of the chemical. It will be understood that, the water below the interface has a low concentration of the chemical since it is not in direct contact with the base of the lower most chemical tablet 210-n. Hence, the difference in the concentration of the chemical in the water causes the formation of a concentration gradient of the chemical across the diffuser 222. Thus, due to the concentration gradient of the chemical across the diffuser 222, the chemical diffuses through the diffuser 222 into the water at a certain rate. Additionally, the concentration gradient between the diffuser 222 and the channel 230 further controls the concentration of the chemical in the dosed water. In an implementation, the rate of the diffusion of the chemical into the water may be based on the concentration gradient, thus ensuring controlled dissolution of the chemical and dosing of chemical at a certain rate into the water.

[0039] Figure 3 illustrates various components of the valve unit 1 16 of the dosing device

104, according to an embodiment of the present subject matter. As previously described, the valve unit 1 16 includes the valve unit inlet 202 the valve piston 204, the valve unit outlet 208, and the casing 220. The water to be dosed enters the valve unit 1 16 through the valve unit inlet 202 as shown by an arrow 302. Further, the valve piston 204 includes an upper seal 304 and a lower seal 306, to provide sealing between the casing 220 and the valve piston 204. The sealing may prevent seepage of water into the dosing unit 1 18. Additionally, the sealing may be provided so that a constrained motion of the valve piston 204 is obtained. The constrained motion of the valve piston 204 may be used to ensure that only a fixed amount of the water enters into the valve unit 1 16. Further, a water router 308 may be provided in between the upper seal 304 and the lower seal 306 to route the water from the valve unit inlet 202 to the valve unit outlet 208. [0040] In operation, when the valve piston 204 is in its top most position 310 the lower seal 306 is below the valve unit inlet 202 and the valve unit outlet 208 to allow the water to enter the valve unit 1 16. The water router 308 provides path to the incoming water to flow into the auxiliary tube 226 via the water router 308 as shown by an arrow 312. Further, a downward motion of the valve piston 204 closes the valve unit inlet 202. As the upper seal 304 closes the ¾ valve unit inlet 202, the flow of water through the valve unit 202 is completely stopped. Once the . flow is stopped, it may not be restarted without an external force due to the irreversible motion of- the link 206. Thus, in the cases where the chemical tablets 210 have been consumed, ingress of water into the dosing device 104 may be stopped. Also, the upper seal 304 may close the valve . unit inlet 202 when the dosing device is not in operation, for example in cases of standby or . fault.

[0041] Figure 4 illustrates various components of the dosing unit 18, according to an embodiment of the present subject matter. As already stated, the dosing unit 1 18 includes the plurality of chemical tablets 210 and the tablet holder 212 attached to the casing 220 in a leak proof manner. Further, the dosing unit 1 18 may include the indicator 216 resting on the top most chemical tablet 210-1 to indicate remaining life of the dosing device 104. The indicator 216 may also be coupled to the spring 214 to keep the chemical tablets 210 under pressure in the tablet holder 212. The spring 214 on one end rests on an upper surface 402 of the indicator 216. The other end of the spring 214 is restricted by the spring support 218 and is in contact with a lower surface 404 of the spring support 218. Further, the diffuser 22 may be placed at a lower end of the casing 22 such that the diffuser is in contact with the chemical tablets 210. [0042] In operation, the water touches the lower surface 406 of the diffuser 222 and due to a capillary action the water seeps through the diffuser 222 to reach an upper surface 408 of the diffuser 222. The bottom surface 410 of the lower most chemical tablet 210-n, being in contact with the upper surface 408 of the diffuser 222, gets wet and hence starts dissolving. This dissolution of the chemical at the interface of the bottom surface 410 of the lower most chemical tablet 210-n and the upper surface 408 of the diffuser 222 creates a concentration gradient across the diffuser 222. The concentration gradient across the diffuser 222 helps in maintaining a predetermined concentration of the chemical in the water below the lower surface 406 of the diffuser 222. As it will be understood that, the concentration of the chemical in the water below the diffuser 222 is substantially less than at the interface. Hence, owing to the configuration of the diffuser 222 a difference in the concentration of the chemical across the diffuser is maintained. Thus, due to the concentration gradient of the chemical across the diffuser 222, the chemical starts diffusing through the diffuser 222 into the water at a very low rate. In an implementation, the rate of the diffusion of the chemical into the water may be based on the concentration gradient, thus ensuring controlled dissolution of the chemical and dosing at a very low and certain rate into the water. Additionally the concentration gradient established in water between the diffuser 222 and outlet 230 further controls the concentration of the chemical in the dosed water.

[0043] In an embodiment, the dissolution of the chemical tablets 210 cause the indicator 216 to move downward under the force of the spring 214. This gives an indication to the user about the spent life of the dosing unit 1 18 or the total amount of water that has passed through the dosing unit 1 18.

[0044] Figure 5 illustrates various components of the liquid collection unit 120, according to an embodiment of the present subject matter. As previously described, the liquid collection unit 120 may include the auxiliary tube 226 and the liquid chamber 228. Further, the auxiliary tube 226 may include a collection inlet 502 to receive water from the valve unit 1 16.

The liquid chamber 228 may be provided with cross section substantially larger than the auxiliary tube 226 so as to lower the turbulence of the water, as previously described.

Furthermore, the liquid chamber 228 may include a dosing unit slot 504 to house the dosing unit 1 18 such that a part of the dosing unit 1 18 may be in contact with the channel 230. The dosing unit slot 504 may hold the dosing unit 1 18 just above the channel 230. [0045] In operation, the water from the valve unit 1 16 enters into the liquid collection unit 120 via the collection inlet 502 as shown by an arrow 506. The water entering from the auxiliary tube 226 is collected in the liquid chamber 228. Further, the dosing unit 1 18 doses the chemical into the water collected in the liquid chamber 228 at a predefined rate. The dosed water may be provided to a collection container 106 via the channel 230.

[0046] Figure 6 illustrates various components of the dosing device 104, according to another embodiment of the present subject matter. As mentioned previously, the dosing device 104 includes the valve unit 1 16 to control the flow of water through the dosing device 104, the dosing unit 1 18 to dose a predefined amount of the chemical to the water passing through the dosing device 104, and the liquid collection unit 120 to collect water coming from the valve unit 1 16 and facilitate the dosing unit 1 18 to dose predefined amount of chemical to the water. Further, the dosed water may be discharged from the dosing device 104 via the liquid collection unit 120.

[0047] The valve unit 1 16 of the present embodiment includes the valve unit inlet 202 and a valve unit outlet 602 to allow the flow of water through it. The valve unit 1 16 may also include a tube. 604, which may be incorporated in the valve unit 1 16 by means of an upper adaptor 606 and a lower adaptor 608 within the valve unit 1 16 in a leak proof manner. The tube 602 may be flexible and may be composed of rubber, silicon rubber, neoprene, leather or any other suitable flexible material. The valve unit 1 16 may also include a stopper base 610, and an indicator 612 coupled to the dosing unit 1 18 to control the flow of water through valve unit 1 16.

[0048] Further, the liquid collection unit 120 may include a liquid chamber 228 to collect water from valve unit 1 16 and facilitate dosing of the chemical from dosing unit 1 18. The liquid chamber 228 may be provided with an orifice 614 to remove air trapped in the liquid chamber 228 and the channel 230 to discharge dosed water out of the dosing device 104. [0049] The dosing unit 1 18 may include the chemical tablets 210 stacked on the diffuser

222. In said embodiment, the indicator 612 placed may be placed on the top most chemical tablet 210-1. The dosing unit 1 18 may also include the spring 214 to keep the chemical tablets 210 and the indicator 612 in place. Further, as the chemical tablets 210 are consumed and distance between the stopper base 610 and the indicator 612 lessens, the spring 214 may push or pinch the tube 604 by way of the stopper base 610 and the indicator 612 to provide necessary force required to control the flow of water in valve unit 1 16. The indicator 612 may also function as an indicator of remaining usable life of the dosing unit 1 18.

[0050] For the purpose of explanation and not as a limitation, the flow of water through the various components of the dosing device 104 may be understood with the following description. In operation, water to be dosed is received by the dosing device 104 via the valve unit inlet 202 and is provided to the liquid chamber 228. The channel 230 controls the flow of water by way of having a smaller diameter than that of the valve unit inlet 202, which in turn also makes the water level rise. Further, air trapped in the liquid chamber 228 below diffuser 222 may escape through the orifice 614 with the rise of water level to ensure complete wetting of the bottom surface of the diffuser 222. The water then emerges from the orifice 614 and facilitates continuous flow of dosed water just below the diffuser 222. Due to capillary action, water rises in the diffuser 222 and the water comes in contact with the bottom surface of the bottom most chemical tablet 210. Consequently, the lower most chemical tablet 210-n starts dissolving and the dissolved chemical diffuses through the diffuser 222 to the water in the liquid chamber 228. [0051 j As the water continues to enter the liquid chamber 228, the above-mentioned process also continues to dose the chemical to the incoming water. Once the ingress water in the dosing device 104 discontinues, water level in the liquid chamber 228 comes down and eventually water stops touching of the diffuser 222, thereby preventing the dissolution, off the lower most chemical tablet 210-n. It will be understood that as the flow of water restarts, the dosing process may be repeated. Further, as the chemical tablets 210 dissolve, the indicator 612 may move downwards due to the spring force acting on it. As the dissolution of chemical tablets 210 nears to its completion, the indicator 612 approaches the stopper base 610 due to which the tube 604 may be pinched under spring force and to stop the flow of water through dosing device 104. [0052] Figure 7 illustrates various components of the valve unit 1 16, according to another embodiment of the present subject matter. As previously described, the valve unit 1 16 may include a valve unit casing 702 housing the valve unit inlet 202, the valve unit outlet 602, and the tube 604. The water enters into the valve unit 1 16 via the valve unit inlet 202, as illustrated by an arrow 704, to reach an upper chamber 706. From the upper chamber 706, the water may pass through the tube 604 and to reach a lower chamber 708 to finally exit the valve unit 1 16 via the outlet 704. Additionally, the valve unit 1 16 includes the upper adaptor 606 and the lower adaptor 608 to hold the tube 604 in the valve unit 1 16 in a leak proof manner. As mentioned previously, the valve unit 1 16 also includes the stopper top 612, which slowly comes down during the course of operation of the dosing device 104. Further, when the indicator 612 comes closer to the stopper base 610, the tube 604 may be pressed in between the stopper base 610 and the indicator 612 thereby stopping the flow of water through the valve unit 1 16. It then comes to the upper chamber 706 and enters into the flexible tube 702 through the tube inlet 706. From the flexible tube 702, water comes out by tube outlet 708 and collects into the lower chamber708.

[0053] Figure 8 illustrates various components of the dosing unit 1 18, according to another embodiment of the present subject matter. The dosing unit 1 18 includes a dosing unit input 802 to receive water from the valve unit 1 16, as indicated by an arrow 804. The dosing unit 1 18 further includes a diffuser 222 to facilitate controlled dosing of the chemicals from the chemical tablets 210. Further, the dosing unit 1 18 includes the indicator 612 resting on the top most chemical tablet 210-1 and extended into the valve unit 1 16 to provided necessary spring force to control the flow of water through the valve unit 1 16. The spring 214 on one end rests on an upper surface of the stopper top 612. The other end of the spring 214 is restricted by the casing 220. As mentioned previously, the diffuser 222 may be placed inside the casing 220 such that it is above the liquid collection unit 120. [0054] During operation, the water in the liquid collection unit 120 touches the lower surface 406 of the diffuser 222 and due to the capillary action, the water seeps through the diffuser 222 to reach the upper surface 408 of the diffuser 222. The bottom surface 410 of the lower most chemical tablet 210-n, being in contact with the upper surface 408 of the diffuser 222 gets wet and hence starts dissolving. The dissolution of the chemical at the interface of the bottom surface 410 of the lower most tablet 210-n and the upper surface 408 of the diffuser 222 creates a concentration gradient of the chemical, across the diffuser 222. The concentration gradient across the diffuser 222 helps in maintaining a predetermined concentration of the chemical in the water in liquid collection unit 120.

[0055] Figure 9 illustrates a graph 900 depicting performance of a dosing device, such as the dosing device 104, in accordance with an embodiment of the present subject matter. To determine the performance of the dosing device 104, the dosing device 104 was supplied with about 900 liters of the water. Further, a chlorine releasing tablet was used for dosing of chlorine into the water and the amount of chlorine dosed was measured by measuring free chlorine in the output water using methods known for measurement of free chlorine. [0056] In the graph 900, total amount of water, in liters, passed through the dosing device

104 is taken as a reference position and is represented along a horizontal axis 902. In the present example, abut 2000 liters of water was passed through the dosing device. Vertical axis 904 represents free chlorine concentration in the water. Curve 906 represents free chlorine concentration in the chemical dosed water. [0057] As seen in the graph 900, the free chlorine concentration in the chemical dosed water falls in the range of about 0.1 to 0.6 ppm across the predicted life of the chemical tablet. Further, it can be observed that an average concentration of about 0.25 ppm is maintained and 0.2ppm is the most frequent data, i.e., most frequent concentration. This shows that present device provides for predetermined concentration of the chemical in the dosed water. [0058] Although implementations of a dosing device have been described in language specific to structural features, it is to be understood that the appended claims are not necessarily limited to the specific features described. Rather, the specific features are disclosed as implementations of the dosing devi ce.

Claims

ΐ/We claim

1. A dosing device (104) for dosing of chemicals in liquids, the dosing device (104) comprising: a valve unit (1 16) configured to control the flow of liquid entering the dosing device (104); a liquid collection unit (120) to receive the liquid from the valve unit (1 16); and a dosing unit (118) in fluid communication with the liquid collection unit (120), wherein the dosing unit (1 18) includes a diffuser (222) to facilitate dosing of the chemical in the liquid flowing through the liquid collection unit (120).

2. The dosing device (104) as claimed in claim 1, wherein the diffuser (222) is a permeable media comprises at least one of felt, nylon, polypropylene, polyamide, and polyester fibers.

3. The dosing device (104) as claimed in claim 1 , wherein the valve unit (1 16) comprises a valve piston (204) configured to open and close a valve unit inlet (202) to control the flow of the liquid through the valve unit (1 16).

4. The dosing device (104) as claimed in claim 1 , wherein the valve unit (1 16) comprises: an indicator (612); a stopper base (610); and a tube (604), wherein one end of the tube (604) is coupled to the indicator (612) and another end of the tube (604) is coupled to the stopper base (610). .

5. The dosing device (104) as claimed in claim 4, wherein the dosing unit (1 18) includes a spring (214) coupled to the indicator (612), and wherein the indicator (612) is configured to move under a force exerted by the spring (214) such that the tube (604) is pressed between the stopper base (610) and the indicator (612).

6. The dosing device (104) as claimed in claim 1 , wherein the liquid collection unit (120) comprises: an auxiliary tube (226) to receive the liquid from the valve unit (1 16); and a liquid chamber (228) to receive the liquid from the auxiliary tube (226), and wherein the liquid chamber (228) is in fluid communication with the dosing unit (1 18).

7. The dosing device (104) as claimed in claim 1, wherein the liquid collection unit (120) comprises a liquid chamber (228) to receive the liquid from the valve unit (1 16), and wherein the liquid chamber (228) is provided with an orifice (614).

8. The dosing device (104) as claimed in claim 1 , wherein the dosing unit (1 18) comprises: a spring (214); an indicator (216, 612) coupled to the spring (214); and one or more chemical tablets (210) comprising the chemical to be dosed, wherein the one more chemical tablets (210) on one end are coupled to the indicator (216, 612) and on other end are coupled to the diffuser (222).

9. The dosing device (104) as claimed in claim 1 , wherein the dosing unit (1 18) further comprises a tablet holder (212) to hold the one or more chemical tablets (210).

10. The dosing device (104) as claimed in claim 1 , wherein the indicator (216, 612) is configured to move under a force of the spring (214) to indicate a remaining life of the dosing device (104).

1 1. The dosing device (104) as claimed in claim 1 , wherein the dosing unit (1 18) is configured to maintain an average concentration of : about 0.20 parts per million (ppm) in the liquid egressing the dosing device (104).