Field of the invention
The present invention relates to a method and system for monitoring the life of a filter in a water purifier. More particularly, the present invention relates to measurement of actual life of the filter membrane in a water purifier.

Background of the invention
Water, being one of the basic necessities of life, is required in every sphere. Since, the water bodies are subjected to various pollutants; they become a source of numerous communicable and fatal diseases. Hence, purification of water is of vital importance. Such purification is performed by water purifiers employing the technique of Reverse Osmosis (RO). Water purifiers remove harmful contaminants from source water and provide pure water that is fit for drinking.

The life of the water purifier depends upon various factors including the type of purifier being used such as RO/ UV / GRAVITY etc., quality of the product, quality of input water, regular maintenance, hours and volume of water used, etc. The best defence system of a water purifier is a filter that is capable of filtering harmful contaminants from polluted water. The most important part of any water purifier is RO membrane. RO membrane reduces the TDS (Total Dissolved Solids) level by up to 90% depending on the quality of RO membrane.

The life of RO membrane depends on input TDS level and usage of said membrane. High level of input TDS level results in low life of the membrane filter and vice-versa. Generally, filters like sediment, carbon etc. available in the water purifier have a life ranging from 6 to 12 months. Such filters are required to be replaced in 1 year of time including RO membrane.
The most important factor that governs the life of a filer is the quality of input water. For instance, a water purifier is designed for a limit of 2000 TDS, in such a case the life of the RO membrane will be less and such purifier would produce better results for input TDS of 500.

Such a system and method has been described in CN 205832761. Said invention relates to a utility model relates to a water purification unit, the utility model discloses a filter element service life indicating device with automatically function of cutting off water supply, it includes controller (320), filter element service life indicator (3) of cutting off the water supply solenoid valve (1) and being connected with filter core (2), be equipped with traffic collection device (31) in filter element service life indicator (3), traffic collection device (31) are used for gathering filter core (2) and actually cross the water yield and send the traffic signal who gathers for controller (320), controller (320) are used for handling and just controlling cut off the water supply solenoid valve (1) according to the comparative result rather than the flow upper limit value comparison of interior settlement received traffic signal. The utility model discloses a gathering the filter core and actually crossing the water yield whether determine filter element service life becoming due, its water consumption of can intelligent reaction user purifying waste water can in time be cut off the water supply when filter element service life is becoming due simultaneously, stops to make water, and it has low cost just can effectively guarantee the user security water.

Such a system and method has been disclosed in US 6306290. Said system relates to a water filter replacement indicator for apparatus that utilizes a filter for purifying water which has a power supply (20) and an auxiliary power supply (22). A timer (24) receives electrical energy from one of the power supplies, generating a first output signal indicating timed intervals. A divider (26) receives this first output signal quantifying the signal until a predetermined number of modulations are perceived at which time it produces a second output signal. A counter (28) receives the second output until a predetermined number of events are perceived at which time it produces a third, fourth and fifth output signal. The third output signal energizes a green light (30) indicating that the filter is operating within its usable life. The fourth output signal energizes a yellow light (32) indicating that the filter is about to reach its predetermined life span. The fifth output signal energizes a flashing red light (34) designating that it is time for filter replacement, further, when the red light is energized the green and yellow light are disengaged.

Such a system and method has been disclosed in US 6334959. Said invention relates to a method of measuring the remaining useful life of a filter may comprise flowing a particulate-laden fluid through a filter and measuring a parameter of the flow during the flowing. From the measurements of the parameter, measurements of the remaining useful life of the filter that vary linearly during the time in which the fluid is flowing through the filter may be produced. The method may include, storing in a store a previously measured correlation between the parameter and the remaining life for a trial filter corresponding to the filter on flowing the particulate-laden fluid there through. The store may receive the measurements of the parameter and output measurements of the remaining useful life corresponding to the received measurements of the parameter and derived from the previously measured correlation.

The water purifiers as described in the prior art calculate the filter life by measuring the pump running time and does not consider the input TDS level. In such a case the purifier stops providing pure water after a fixed period time even if the filter is in good state. Said purifiers require high maintenance cost and the filters are replaced after every fixed interval of time.

Objective of the Invention
The objective of the present invention is to design a technique for purifying water through water purifiers that requires cost effective maintenance and does not require regular replacement of the membrane filters of said water purifiers.
The instant invention achieves the objective by employing the technique of measuring the life of the filter membrane and replacing said filters only after the filter gets damaged.

Summary of the Invention
The present invention relates to a method and system for monitoring the life of a filter in a water purifier. More particularly, the present invention relates to measurement of actual life of the filter membrane in a water purifier.

The instant invention relates to a method for determining the life of a RO membrane filter in a RO water purification system, said method comprising the steps of: placing a weight or pressure sensor at the bottom of the tank of said RO water purification system; inferring the water level in said tank as passed through the RO membrane filter into the tank; decision making is performed by said sensor; transmitting signal from said sensor to a controller; and monitoring the signal as sent to the controller.

The instant invention also relates to an RO water purification system for determining the life of a RO membrane, said system comprising of: a water filter; a tank; a sensor; a controller PCB.
The normal life cycle of a filter of a water purifier, as depicted in Figure 3, is as follows: Considering that the input water condition is same throughout the life cycle of the filter, during initial phase of life of the filter, said filter provides some X ml amount of water while during the intermediate life some Y ml of water is provided. The Y amount is less than the X amount. Now if filter is near the end of life then the output will be something Z ml and said amount is very less than X. The time taken by the water purifier to reach to the Z level depends on the input TDS condition. Hence, a technique that is capable of measuring the actual life of the filter membrane is employed so as to ensure the replacement of the membrane only when the filter life gets over.

According to an embodiment of the present invention, if a weight level sensor is placed on the tank of the purifier, as illustrated in Figure 5, then the user can easily infer the current water level available on the tank. Depending on the weight of the water the purifier provides depends on the water level data as per the tank capacity. Whenever weight of the water is less then it means tank is having low water level and similarly and if the weight data is higher it means tank has good amount of water. Actual data could be calculated with the help of feedback from the system. The pressure sensor may also be placed in place of weight sensor. The decisions are based on the pressure created by water on the sensor.

When water will pass through the membrane filter then said purifier will provide the water depending on the conditions of the water purifier. Now this water is passed into the storage tank of the product. Whenever the water purifier is going to start to fill the tank said purifier will always have the current level of water available in the tank. Weight sensor will be giving that information to the controller and controller will do the internal calculation to calculate the water level.
According to a preferred embodiment of the present invention, the life of the RO membrane is monitored depending upon the amount of output water and the actual condition of said RO membrane. The output water quantity through the RO membrane is more if the RO membrane filter is in good condition and in case said membrane filter is used for a good amount of time then depending upon the condition of the input water, the amount of output water will be less. Said output water is passed into the storage tank and depending upon the quantity of water being passed into the said storage tank the level of the tank changes accordingly. The time taken to fill up the tank is measured by the weight sensor and accordingly the signal is sent to the controller.

According to another preferred embodiment of the present invention, said concept may be employed for identifying if input supply is coming proper to the product or not or the supply is coming with very low water pressure (which could be identified by LPS switch). There are chances when there is no supply available to the water purifier. In this situation, controller may feel that filter membrane is not giving any water then the controller should release the filter replace notification.

Said condition could be separated for actual filter failure situation in such way that when there is no change in the water level continuously for T minutes then it might be possible that there no supply to the input side as well. Controller will release different kind of notification like no water supply or low water pressure etc. With this, the water purifier doesn’t need any specific kind of sensor to identify the input water problem.

Brief Description of the drawings

The drawings of the instant invention illustrate the working of said concept.

Figure 1 illustrates the weight sensor placement on the tank.
Figure 2 illustrates the weight sensor signals depending upon the status of the tank.
Figure 3 illustrates the life cycle of a RO filter life.
Figure 4 depicts the block diagram for the working of the concept.
Figure 5 illustrates the states for measuring the level of water and calculating the time taken to fill the tank by the controller.

Whenever purification is starting, Controller already knows that how much time will be taken to fill the extra N ml of water in the tank when filters are in good conditions. Considering that tank has some L level of water when the filling of water stops. Now when tank starts filling then weight level sensor will keep giving signal to controller about the current water level in tank. When controller gets the input from the sensor that now the water level has gone up from L to L+1 then controller will calculate time taken by product to fill that extra 1 level of water. If the time calculated is under the defined limit then notification will be released.

When the time taken by membrane filter starts getting higher and falls under the advance alert for the filter replacement controller will release the notification to water purifier to display that membrane filter life is getting near end. Similarly, time will come when this time taken by the product will go out of defined limit then controller will release the notification that filters life can come to an end and there is a need to replace the filters immediately to keep getting purified water. This condition is very close to actual end of life of membrane filter.

CLAIMS
1. A method for determining the life of a RO membrane filter in a RO water purification system, said method comprising the steps of:
i. placing a sensor at a tank of said RO water purification system;
ii. inferring the water level in said tank as passed through the RO membrane filter into the tank;
iii. decision making is performed by said sensor;
iv. transmitting signal from said sensor to a controller; and
v. monitoring the signal as sent to the controller;
2. Characterized in that the data on said signal varies according to the water level of the tank and said variations are monitored to infer the life of said RO membrane. The method as claimed in Claim 1, wherein said sensor provides for the water level data in the tank as per the capacity of the tank.

3. The method as claimed in Claim 1, wherein the actual data is calculated by a feedback from said system.

4. The method as claimed in Claim 1, wherein a microcontroller measures the time taken to fill the water between two levels and derive a conclusion.

5. The method as claimed in Claim 1, wherein an advance alert is set in the water purification system whereby the controller releases a notification to the display for replacement of the RO membrane filter as said filter life is near the end and is left with little time.

6. An RO water purification system for determining the life of a RO membrane, said system comprising of:
i. a water filter;
ii. a tank;
iii. a sensor;
iv. a controller PCB

7. The system as claimed in Claim 8, wherein the sensor may be a weight sensor or a pressure sensor.

8. The system as claimed in Claim 8, wherein a weight sensor is placed at the bottom of the tank of said water purification system.