Abstract:
An ozone water producing system and control method, which is flexibly used indoor or outdoor irrespective condition of a flow channel, is provided for reconstituting polluted water as environmentally friendly. The ozone water generating system is maintained in an optimum state for improving entire performance of the system as well as predicting and preventing the backflow of ozone water, which is occurred due to outlet blocking in a discharging process. The controlling method of the present ozone water producing enables to prevent the deteriorating the performance and ensure the operation stability. The ozone water-producing system comprises an influent air controller, an injector, a gas-liquid separator, and an ozone water-backflow, preventing device. The present system and controller is designed to prevent water backflow, being frequently occurred in the conventional system, for improving the performance, stability and extending operating lifetime. Therefore, it is possible to manufacture a highly reliable ozone water-producing apparatus.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a system for producing ozone water containing dissolved ozone in which polluted water is reproduced as environmentally friendly. More particularly, the present invention relates to an ozone water-producing system and its control method in which an ozone water-producing apparatus can be all purposely used indoors or outdoors irrespective of the condition of a flow channel. The condition of ozone generation is maintained in an optimum state so as to improve the performance of the system in its entirety, as well as to mitigate the symptom of the backflow of the ozone water due to a blocking of an outlet in the process of discharging. The ozone water is previously detected to prevent deterioration of the system performance and ensure stability in use. 
     2. Background of the Related Art 
     In general, it is known that an ozone water-producing apparatus that can obtain ozone water by mixing and dissolving ozone into water utilizes the strong oxidation effects of ozone for the purpose of purification and disinfections. The ozone water-producing apparatus can be classified into a pressurized injector type, a diffused air type or a venturi injector type, etc., depending on the ozone water-producing method. 
     Among them, a typical ozone water-producing apparatus of the pressurized injector type, as shown in FIG. 1, includes an air pump  10  which sucks external air to provide to the apparatus as intake air, an ozone generator  11  with an ozone-generating unit  12  for changing oxygen contained in the air supplied from the air pump  10  into ozone to generate ozone, a mixer  14  for mixing the ozone supplied from the ozone generator  12  with water supplied from a water source  13 , a solenoid valve  16  installed in a water supply line  15  to control a flow of the water supplied to the mixer  14  from the water source  13 , etc. 
     The ozone water-producing apparatus is configured in such a fashion that when the air pump  10  supplies air to the ozone-generating unit  12  compulsorily, the ozone-generating unit  12  changes oxygen in the air into ozone. At this time, although a portion of the changed ozone is again decomposed into oxygen, most of the ozone is pushed into the mixer  14  which, in turn, mixes the ozone into water supplied from the water source  13  so as to discharge ozone water. 
     Accordingly, in such a pressurized injector type ozone water-producing apparatus, the ozone is sucked into the mixer  14  by the negative pressure generated when water from the water source  13  passes through the water supply line  15  while pressure is generated by the air pump  10  so as to discharge ozone water where gas and liquid are mixed, i.e., water which contains dissolved ozone. 
     The ozone water-producing apparatus requires various peripherals since maintaining a suitable degree of water and ozone mixing relates to the performance of the apparatus. Examples of auxiliary devices for stably and uniformly maintaining the mixing state of water and ozone to provide optimum water containing dissolved ozone include a mixer for mixing ozone and water, an injector for generating a negative pressure, a gas-liquid separator for controlling the amount of air introduced thereto or separating gas and liquid, etc. 
     Examples of techniques for providing an improved ozone water-producing system through a modification of the arrangement and structure of the ozone water-producing apparatus are described below. The Korean Utility Model Registration No. 208,109, introduced by the applicant of the present invention, discloses an apparatus for producing ozone water in which a solenoid valve (injector) is modified, a bubble separator is installed in an ozone supply line connected to an inlet of a mixer. In this system only an increase in water pressure permits the inflow of ozone without an air pump, the discharge of surplus ozone not mixed into the water is prevented and a reduction in the number of components and miniaturization achieved according to the absence of the air pump in the overall construction. Also, various problems associated with a re-use of the ozone including possible physical harm to humans due to the ozone as well as breakage of the peripheral components are resolved. 
     Another Korean Utility Model Registration No. 203,244, introduced by the applicant of the present invention, discloses an apparatus for producing ozone water in which a problem associated with security of the length of a flow channel due to an additional installation of a solenoid valve and an injector on the flow channel is overcome in such a manner that the flow channel length is shortened and an air pump is replaced while obtaining suitable ozone water through an integrated application of the solenoid valve and injector. 
     However, such conventional arts are directed to a modified structure of a flow channel for mixing artificially generated ozone and water. Particularly, there has been a problem in that the use of air containing foreign substance and moisture to generate ozone causes deterioration of the ozone-producing efficiency. 
     In addition, there occurs a frequent blocking of an outlet of ozone water during system operation. In this case, the ozone water deviates from a normal flow path and flows backwards so that a mixed balance between water and ozone is destroyed, simultaneously making the normal discharging of ozone water impossible. As a result, along with a decrease in the entire flow channel performance, a user can feel inconvenienced by having the need to obtain maintenance and repair of the system from those highly skilled in the art. 
     Moreover, there has not been suggested a concrete approach for efficient control, a concrete system design and an ozone water producing apparatus that can be easily and simply utilized in home, public facilities or the like. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to an ozone water-producing system and its control method that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
     An object of the present invention is to provide an ozone water producing system, which can be all purposely used indoors or outdoors irrespective of the condition of a flow channel. 
     Another object of the present invention is to provide an ozone water-producing system that maintains the condition of ozone generation of the system in an optimum state to achieve an improved performance in its entirety. 
     Still another object of the present invention is to provide an ozone water-producing system that preemptively detects a symptom of the backflow of ozone water due to a blocking of an outlet in the process of discharging the ozone water to prevent deterioration of the system performance and ensure stability in use. 
     Yet another object of the present invention is to provide an ozone water-producing system that controls relatively frequently occurring backflow of water during the operation of the ozone water-producing system to allow the system to operate normally. 
     Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as in the appended drawings. 
     To achieve these objects and other advantages, and in accordance with the purpose of the invention as embodied and broadly described herein, according to an aspect of the present invention, there is provided an ozone water-producing system including, an ozone generator having an ozone-generating unit for receiving air and changing oxygen contained in the air into ozone, a mixer adapted to mix the ozone supplied from the ozone generator with water supplied from a water source, a solenoid valve installed in a water supply line to control the flow of the water supplied to the mixer from the water source, and a gas-liquid separator adapted to separate gas and liquid. 
     The ozone water-producing system comprising: influent air control means adapted to purify and dehumidify introduced air that passes through an air solenoid valve installed in the flow path of ambient air introduced into an ozone generator; an injector connected to a water supply line and an ozone gas supply line so as to form an ozone gas with air purified and dried through the influent air control means and mix the ozone gas with water, the injector adapted to open a check valve installed at a position where the ozone gas supply line and the water supply line meet by means of water injection via the Venturi effect to allow the ozone gas to be dissolved into water; a gas-liquid separator having a certain space enabling a separation of gas and liquid and adapted to perform a repeated ozone dissolving process in such a manner that it receives first ozone water obtained by mixing and dissolving the ozone gas into the water via the injector, allows ozone to subsequently be dissolved into water to produce second ozone water in the gas-liquid separator and discharges ozone water of a liquid state where ozone is dissolved into water during the formation of the second ozone water through a drainpipe while allowing ozone in a gaseous state which is not dissolved into water to re-enter the gas-liquid separator through a return line to allow ozone to thirdly be dissolved into water to produce ozone water in the gas-liquid separator; and ozone water-backflow preventing means installed along the interior space of the gas-liquid separator and adapted to detect a limited water level of the ozone water introduced into the gas-liquid separator and control the flow of water through the water supply line according to the flow state of the ozone water in order to prevent a backflow of the ozone water. 
     According to another aspect of the present invention, there is also a method of controlling an ozone water-producing system for producing ozone, comprising the steps of: 
     supplying water to the interior of the system by opening a water solenoid valve serving to open and close a water supply line in a driving circuit board, and mixing ozone into the water by increasing a flow rate of the water through an injector and sucking the ozone into the injector; 
     separating ozone from water through a gas-liquid separator to dissolve ozone into water containing dissolved ozone while restricting a discharge of ozone which is not dissolved in the water so as to re-dissolve ozone into the water; 
     continuously supplying water to the gas-liquid separator in the gas-liquid separating process and, in response to a blocking of an outlet provided on the lower portion of the gas-liquid separator, detecting a state where a discharge of water is stopped as an abnormal water level in the gas-liquid separator; 
     blocking the water solenoid valve and opening the outlet on the lower portion of the gas-liquid separator to discharge water from the gas-liquid separator through the outlet if water level detecting information of the gas-liquid separator contains a full water level; and 
     identifying a discharge state of water through a detecting sensor after all the water in the gas-liquid separator is discharged and actuating the water solenoid valve to re-supply water to the gas-liquid separator through the water supply line after an optional delay time elapses. 
     According to the ozone water-producing system, the condition of ozone generation is maintained in an optimum state to improve stability and performance of the system in its entirety. Further, the re-circulation of ozone increases the amount of dissolved ozone, reduces inconvenience according to maintenance and repair of the system, and allows the system to be flexibly used indoors or outdoors irrespective of the condition of a flow channel. 
     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
     FIG. 1 is a schematic elevation partly in section illustrating a general ozone water producing apparatus. 
     FIG. 2 is a view illustrating the overall construction of an ozone water producing system according the present invention. 
     FIG. 3 is a view illustrating an influent air control unit of the present invention, in which FIG.  3 ( a ) is an elevation view in section of the unit, and FIG.  3 ( b ) is a side view in section of FIG.  3 ( a ). 
     FIG. 4 is a schematic view illustrating the construction of an injector of the present invention. 
     FIG. 5 is a sectional view illustrating the inner construction of a gas-liquid separator and a water-backflow preventing unit according to the present invention. 
     FIG. 6 is a view illustrating the operating condition of the system, especially a view for referring to a flow channel, which illustrates the air flowing state of a specific heating block. 
     FIG. 7 is a comparative referring view of FIG.  6 . 
     FIG. 8 is a table illustrating a comparison between the opening time of an air solenoid valve and the driving time of two heating blocks under the air influent condition for operating the two heating blocks according to an embodiment of the present invention. 
     FIG. 9 is a flowchart illustrating a controlled method of delaying the time when water will be re-supplied according to the construction of the gas-liquid separator of FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in FIGS. 2 to  9 . 
     An ozone water-producing system according to the present invention includes an ozone generator having an ozone-generating unit for receiving air and changing oxygen contained in the air into ozone to generate the ozone, a mixer adapted to mix the ozone supplied thereto from the ozone generator with water supplied thereto from a water source and a solenoid valve installed in a water supply line to control a flow of the water supplied to the mixer from the water source, an influent air control unit, an injector, a gas-liquid separator, and a unit for preventing backflow of ozone water in the gas-liquid separator. 
     As shown in FIG. 2, the influent air control unit  40  functions to purify and dehumidify intake air through an air solenoid valve  30  installed in the flow path of ambient air introduced into an ozone generator  20 . The injector  60  is connected to a water supply line  50  and an ozone gas supply line  51  so as to form an ozone gas with air purified and dried through the influent air control unit  40  and mix the ozone gas with water, and opens a check valve  52  installed at a position where the ozone gas supply line  50  and the water supply line  51  meet by means of water injection through a flow rate of water to allow the ozone gas to be dissolved into water. The gas-liquid separator  70  has a certain space permitting a separation of gas and liquid so that it receives first ozone water obtained by dissolving the ozone gas into the water via the injector  60  to mix water and ozone so as to produce second ozone dissolved water, and discharges ozone water in a liquid state where ozone is dissolved into water during the formation of the second ozone dissolved water through a drainpipe  53  while allowing ozone in a gaseous state which is not dissolved into water to re-enter the gas-liquid separator through a return line  54  to experience third or more ozone dissolving process. The ozone water-backflow preventing unit is installed along the interior space of the gas-liquid separator  70  to detect a limited water level of the ozone water introduced into the gas-liquid separator  70  and control the flow of water flowing through the water supply line  50  according to the flow state of the ozone water to prevent a backflow of the ozone water. 
     The influent air control unit  40 , as shown in FIGS. 2 and 3, includes a heater  43  on a jacket  42  having an air intake port  41  and an empty interior space, a filter  44  installed at the air intake port  41  of the jacket  42  for filtering sucked air, a dehumidifying layer  45  disposed in the empty interior space of the jacket  42  for removing moisture contained in air passing through the filter  44 . An electrode plate  46  is installed in the jacket  42  and generates heat by means of a Positive Temperature Coefficient (PTC) thermostat element. The dehumidifying layer  45  is filled with silica gel, i.e., a kind of drying agent, that purifies ambient air introduced into the ozone generator  20  and removes moisture contained in the air to allow moisture-free air to enter an ozone-generating unit (not shown) of the ozone generator  20 . 
     As is the case with the heaters  43  and  43   a,  as shown in FIG. 2, one or more heaters may be arranged around an air solenoid valve  30  communicating with an air inflow line forming a flow channel together with the ozone generator  20 . 
     For example, the heaters  43  and  43   a  may be configured in such a manner that the heater  43  is used for purifying and drying air to allow it to enter the ozone generator  20  via the air solenoid valve  30 , while another heater  43   a  is used for actuating the PTC thermostat element  47  to dry silica gel that contains moisture in response to an operating signal of an operating circuit board  55  and both are connected to the air solenoid valve  30 . 
     The heaters  43  and  43   a  are connected to the air solenoid valve  30  through ambient air inflow lines  58   a  and  58   b,  respectively, so air first passes through the air solenoid valve  30  and one side flow channel of the air solenoid valve  30  is connected to the ozone generator  20  through an air supply line  58   c.    
     As shown in FIGS. 2 and 4, the injector  60  is connected at one end to the water supply line  50  and connected at the other end to the gas-liquid separator  70 . A check valve  52  is installed on the external side of the region of the injector  60  where a flow channel narrows so that it can be opened or closed under a certain pressure, and includes an injector hole  61  for allowing the passage of ozone gas into the flow channel of the injector through the check valve, as induced via the Venturi effect due to the high speed flow of water supplied to the injector through the water supply line. 
     As shown in FIGS. 2 and 5, the gas-liquid separator  70  is configured in such a manner that its shape is selected to give a natural rotation to a flow of water injected from the injector  60 . The shape of the gas-liquid separator  70  may be cylindrical, quadrangular, triangular, etc. Among these, a cylindrical gas-liquid separator  70  is more stable for a flow of water. Also, the gas-liquid separator  70  has an upright structure to separate gas and liquid by means of gravity. 
     The upper portion of the gas-liquid separator  70  is closed, but a return line  54  is connected to an inlet  71  side of the gas-liquid separator  70  to recirculate undissolved ozone. Formed at the lower portion of the gas-liquid separator  70  is a passage  72  connected to a drainpipe  53 . A removable cap  76  is situated on an opening formed on the upper portion of the gas-liquid separator  70 . 
     As shown in FIGS. 2 and 5, the ozone water-backflow preventing unit includes a guide  73  fitted into the opening formed on the upper portion of the gas-liquid separator  70 , a rod sensor  74  extended vertically below the upper portion of the gas-liquid separator  70  along the guide  73  within the gas-liquid separator  70  for detecting a water level within the gas-liquid separator  70  by defining a certain level point where the water level within the gas-liquid separator  70  reaches as a full water level, and a water solenoid valve  75  installed in the supply side of the water supply line  50  for controlling the water supply line  50  in response to information detected from the rod sensor  74 . 
     The ozone water producing system including the influent air control unit  40 , the injector  60 , the gas-liquid separator  70  and the ozone water-backflow preventing unit can be publicly used for a household, business and industrial purpose through a suitable arrangement of constituent elements depending on a use purpose. 
     Now, the feature and operation of the ozone water-producing system according to the construction of the present invention will be described in detail hereinafter through an ozone water-producing process and an operation mode. 
     The featuring portion of the present invention is largely classified into five sections: (1) an injecting section  60  which adopts a complex structure of the heaters  43  and  43   a  connected to a driving circuit board  55  and the check valve  53  for allowing ozone generated from the ozone generator  20  to enter the injector  60  by means of a flow rate through the injection of water, (2) an ozone gas re-circulating section using the gas-liquid separator  70  which discharges an ozone gas not dissolved into water through an outlet of the upper portion of the gas-liquid separator  70  to re-introduce the discharged ozone gas into the water supply line  50  via the return line  54  and dissolve it into water in the water supply line  50  and which discharges the water containing dissolved ozone through an outlet of the lower portion of the gas-liquid separator  70 , (3) a water-backflow control section which separates water and ozone when the water enters the gas-liquid separator  70  and intercepts a flow of water entering the gas-liquid separator  70  through the water solenoid valve  75  if the amount of accumulated water exceeds the water level limit within the gas-liquid separator  70  during separation or a standby process, (4) a control section for the water solenoid valve  75  which artificially delays the opening time of the water solenoid valve  75  in order to save the time required to discharge the overflowed water, and (5) a section which purifies polluted ambient air introduced into the ozone generator  20  and removes moisture via dried silica gel to continuously introduce clean and dried air into the ozone generator  20 . Here, a dehumidifying effect of air introduced into the ozone generator  20  may vary with the arrangement of the heaters  43  and  43   a.  In case of maintaining a continuous operation of the system, one or more heaters  43  and  43   a  is disposed so that filtered air is first dried through one heater  43  to be introduced into the ozone generator  20  whereas when moisture is saturated in the dehumidifying layer  45  of the one heater  43  the dehumidifying layer  45  is dried through the PTC thermostat  47  while filtered air is dried through the other heater  43   a  to be introduced into the ozone generator  20 . In this case, the air solenoid valve  30  adopts a 3-way flow channel scheme. But, one or more heaters may not necessarily be disposed. That is, if the operation time of the system is less than about 5 hours and a long dormant state lasts, the natural drying of the dehumidifying layer of the heater  43  or  43   a  is also possible so that a dehumidifying effect can be attained only by using one heater. 
     The operation of the ozone water producing system of the present invention will be described by assuming that two heaters  43  and  43   a  are applied to the system. 
     As show in FIGS. 6 and 7, when a switch (not shown) provided on the driving circuit board  55  is turned on, the water solenoid valve  75  is opened so that water is introduced into the water supply line  50 . 
     At this moment, the ozone generator  20  detects a power supply signal of the driving circuit board  55  and applies an electric power to the ozone-generating unit built in the ozone generator  20  to intermittently or continuously generate ozone depending on a predetermined condition (the generating time and period of ozone can be controlled by the driving circuit board  55 ). 
     Then, water passes through the water solenoid valve  75  continuously and enters the injector  60 , which, in turn, injects the water into the inner space thereof at a flow rate of water through a small injector hole  61  formed within the injector  60 . At this time, ozone generated from the ozone generator  20  is sucked into the small injector hole  61  through the check valve  52  so that an ozone gas is dissolved into the water flowing in the injector  60  while being introduced into the gas-liquid separator  70 . 
     In the flow process of water between the injector  60  and the gas-liquid separator  70 , first ozone water, obtained by mixing and dissolving ozone into water in the injector  60 , is introduced into the gas-liquid separator  70  via the injector  60 . Ozone is subsequently dissolved into water to produce second ozone water in the gas-liquid separator  70 . In this process, gas-liquid separator  70  discharges ozone water of a liquid state where ozone is dissolved into water through a drainpipe  53  while allowing ozone in a gaseous state, which is not dissolved in water, to re-enter the gas-liquid separator  70  through a return line  54  to experience third or more ozone-dissolving processes. 
     As show in FIG. 6, polluted ambient air is introduced into the heater  43  which, in turn, purifies the polluted ambient air through a filter thereof or removes moisture from the purified ambient air through a dried dehumidifying layer  45  to produce clean and dried air and to supply it to the ozone generator  20  through the air solenoid valve  30 . At this time, the flow channel operating time of the heater  43  needed to pass though a flow path of {circle around (3)}→{circle around (1)} is approximately 5 hours. 
     As shown in FIG. 7, in case of using another heater  43   a,  when the PTC thermostat element  47  of the heater  43   a  is activated in response to a driving signal of the driving circuit board  55 , it sufficiently dries the saturated dehumidifying layer  45  of silica gel for about 1 hour. In this way, in the case of applying both the heaters  43  and  43   a,  they are alternately operated in such a manner that one heater  43  functions to purify and dry air whereas the other heater  43   a  functions to dry the dehumidifying layer  45  to perform a standby operation, so that clean and dried air can be continuously supplied to the ozone generator  20 . At this time, after a lapse of the flow channel operating time (about 5 hours) of the heater  43 , as shown in FIG. 7, the other heater  43   a  purifies and dries air to supply it to the ozone generator  20  along a flow path {circle around (2)}→{circle around (1)} of the air solenoid valve  30 . For reference, in case of producing ozone through the ozone-generating unit of the ozone generator  20 , when a humidity of air is relatively low and the purity of the intake air? is high, the amount of produced ozone per unit time can be increased and the production of a high quality ozone is possible. 
     FIG. 8 is a table illustrating a comparison between the opening time of the air solenoid valve  30  and the driving time of two heaters  43  and  43   a  under the air influent condition for operating the two heaters  43  and  43   a  according to an embodiment of the present invention. 
     In the meantime, the first ozone water obtained by mixing and dissolving into water in the injector  60  is introduced into the gas-liquid separator  70  which, in turn, dissolves ozone into water in the gas-liquid separator  70  to produces second ozone water, i.e., water containing dissolved ozone to discharge it through the drainpipe  53 . The discharged second ozone water corresponds to the final product of ozone water to be obtained in the present invention. 
     At this time, ozone gas that is not dissolved into water flows toward an upper portion within the gas-liquid separator  70  and re-enters the gas-liquid separator  70  through the return line  54  so that ozone is thirdly dissolved into water in the gas-liquid separator  70 . Consequently, the above ozone-dissolving process is performed repeatedly so that ozone is dissolved into water in the gas-liquid separator  70 , without being discarded, to produce ozone water that is discharged through the drainpipe  53 . 
     During operation of the ozone water-producing system, according to the present invention, if the drainpipe  53  is closed, the gas-liquid separator  70  fills with water. At this time, when the rod sensor  74  built into the gas-liquid separator  70  detects the water level limit in the gas-liquid separator  70 , the water solenoid valve  75  is closed to prevent a backflow of ozone water. Then, since information about the detected water level limit can stop the driving of the ozone generator, the heating block and the other components, it is possible to prevent damage to the ozone water producing apparatus due to a backflow of ozone water. 
     The configuration for preventing a backflow of ozone water by detecting a water level in the gas-liquid separator  70  can selectively adopt any one of several schemes to predict a backflow of ozone water by detecting a hydraulic pressure in the gas-liquid separator  70 , such as a scheme which applies a proximity sensor and a limit sensor for sensing the height of a water surface, a scheme which senses a backflow of ozone water by actuating a micro-switch to move it to a floating position of a reference scale using buoyancy, etc., as an alternative to a scheme using the rod sensor  75  which recognizes a direct contact with water as a water level limit as shown in FIG.  5 . 
     Now, a method of controlling the ozone water-producing system according to the present invention will be described in detail. 
     First, water is supplied to the interior of the system by opening a water solenoid valve  75  serving to open and close a water supply line  50  in a driving circuit board  55 , and ozone is mixed into the water by increasing a flow rate of the water through an injector  60  and sucking the ozone into the injector  60 . Second, ozone is separated from water through a gas-liquid separator  70  to dissolve ozone into water containing dissolved ozone while restricting the discharge of undissolved ozone so as to recirculate and re-dissolve the ozone into the water. Third, water is continuously supplied to the gas-liquid separator  70  in the gas-liquid separating process and in response to a blocking of an outlet provided on the lower portion of the gas-liquid separator  70  a state where a discharge of water stoppage is detected as an abnormal water level in the gas-liquid separator  70 . Fourth, the water solenoid valve  75  is blocked and the outlet on the lower portion of the gas-liquid separator  70  is opened to discharge water in the gas-liquid separator  70  through the outlet if water level detecting information from the gas-liquid separator  70  indicates a full water level. Lastly, a discharge state of water is identified through a detecting sensor after all the water in the gas-liquid separator  70  is discharged and the water solenoid valve  75  is actuated to re-supply water to the gas-liquid separator  70  through the water supply line  50  after an optional delay time elapses. 
     FIG. 9 is a flowchart illustrating an example of a controlled method (a delay circuit) of delaying the time when water will be re-supplied according to the basic construction of the gas-liquid separator  70  of FIG.  5 . 
     The time needed to delay a re-supply of water is set to be larger than the time required to discharge water in the gas-liquid separator  70 . That is, a delay of the re-supply of water is intended to again supply water to the gas-liquid separator  70  after sufficiently discharging water accumulated in the gas-liquid separator  70  according to the interruption of a discharging of water. Such a water re-supply delaying operation will be described hereinafter under the condition where a rod sensor is employed as a water level detecting sensor. 
     Referring to FIG. 9, first, at S 100 , when a driving power is applied to the driving circuit board  55 , i.e., the driving circuit board  55  is switched on, the program proceeds to step S 200  in which the water lever detecting rod sensor  74  determines whether or not a discharging of water is completed, i.e., water filled into the gas-liquid separator  70  has been exhausted by external manipulation (automatic manipulation or artificial manipulation) in a state where the water solenoid valve  75  is closed. If it is determined at step S 200  that the answer is YES, i.e., the discharging of the water is complete, the program proceeds to step S 300  where an electric power is again applied to the water solenoid valve  75 , i.e., the water solenoid valve is switched on, after 0-5 seconds after the rod sensor  74  is separated from the water, and water is again supplied to the gas-liquid separator  70  (S 400 -S 500 ). Consequently, the water re-supply delaying process is concluded. Alternatively, during an initial operation, since water accumulated in the gas-liquid separator  70  is in contact with the rod sensor  74  and the water solenoid valve  75  is closed, the water solenoid valve  75  is opened after discharging the filled water automatically for a certain time period (0-5 seconds) using a delay circuit, so that water is again supplied to the gas-liquid separator  70  (S 100 -S 500 ). As a result, the water re-supply delaying process is concluded. Therefore, both the water re-supply delaying processes may be employed selectively. Such a control method may vary according the function of a water level detecting sensor and the condition of the gas-liquid separator  70 . 
     As described above, the ozone water-producing system, according to the present invention, has an advantage in that since it is easily and simply installed indoors or outdoors according to a use purpose of various kinds of water such as city water, underground water, industrial and agricultural water, environmental purifying water, public health and hygiene processing water, etc., so that a large quantity of water is continuously processed to produce ozone water, it can be effectively used to reproduce polluted water so that it is once again environmentally friendly. 
     In addition, there is ensured system stability which is not obtained from a conventional ozone water-producing system, and the condition of ozone generation is maintained in an optimum state to improve the performance of the system in its entirety as well as allow unmanned operation. 
     Moreover, a backflow of water occurring highly frequently during the operation of the conventional ozone water-producing system is prevented so that stability and performance of the system are improved and operation life time is extended, which makes it possible to manufacture a highly reliable ozone water producing apparatus. 
     The forgoing embodiments are merely exemplary and are not to be construed as limiting the present invention. The description of the present invention is intended to be illustrative and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art.