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CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a non-provisional patent application based on U.S. Provisional Application Ser. No. 62/193,791, entitled “AIRFLOW MONITOR FOR USE WITH A VACUUM POWERED SEWER SYSTEM”, filed Jul. 17, 2015, which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a monitoring device to detect a defective or stuck vacuum operated valve of a vacuum sewer system. 
         [0004]    2. Description of the Related Art 
         [0005]    A vacuum sewer system is a method of transporting sewage from its source to a sewage treatment plant using negative air pressure. It uses the difference between atmospheric pressure and a partial vacuum maintained in the piping network and vacuum station collection vessel. This differential pressure allows a central vacuum station to collect the wastewater of individual homes. 
         [0006]    The main components of a vacuum sewer system are collection chambers and vacuum valves, sewers, a central vacuum station and monitoring and control components. 
         [0007]    Vacuum technology is based on differential air pressure. Rotary vane vacuum pumps generate an operation pressure of −0.4 to −0.6 bar at the vacuum station, which is also the only element of the vacuum sewerage system that must be supplied with electricity. Interface valves, that are installed inside the collection chambers, work pneumatically. Sewage flows by means of gravity into each house&#39;s collection sump, after a certain fill level inside this sump is reached, the interface valve opens. The impulse to open the valve is usually transferred by a pneumatically (pneumatic pressure created by fill level) controlled controller unit. No electricity is needed to open or close the valve—the energy is provided by the vacuum itself. While the valve is open, the resulting differential pressure becomes the driving force and transports the wastewater towards the vacuum station. When the level of wastewater is lowered to a predetermined level the valve closes to stop the flow of air and wastewater until the level rises enough to trigger the opening of the valve again. Each collection sump has a vent pipe that extends up from the sump so that an unhindered flow of air can enter the sump when the valve is actuated. If the valve does not completely seal there is a flow of air that is effectively an inefficiency in the system since energy is needed to run the vacuum pump. 
         [0008]    Once the wastewater arrives in the vacuum collection tank at the vacuum station, the wastewater is then pumped to the discharge point, which may be a gravity sewer or a treatment facility. 
         [0009]    A weakness of the system lies in the functioning of the valves. The mechanical float switches that operate the valves require preventative maintenance for worn parts and seals. Also, the vacuum valves can get stuck open leading to pressure drops in the entire system. One technique to detect the stuck or non-closing valve is to walk up to a vent pipe and listen to hear a continuous flow of air. This is time consuming in that it has to be done for each sump at each home until the stuck valve(s) is (are) discovered. 
         [0010]    What is needed in the art is an effective monitoring system that allows for the determination of the functioning of the valve from a distance. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention provides a monitoring device to detect a defective or stuck vacuum operated valve of a vacuum sewer system. 
         [0012]    The invention in one form is directed to a vacuum sewer system including at least one home collection system, a central vacuum system coupled to the home collection system and a vacuum valve monitoring system coupled to the home collection system. The vacuum valve monitoring system has an airflow detector and an indicator operatively coupled to the airflow detector, the indicator being configured to emanate an indication that the airflow detector has detected an airflow thereby. 
         [0013]    The invention in another form is directed to a vacuum valve monitoring system that is coupled to at least one home collection system of a central vacuum system. The vacuum valve monitoring system has an airflow detector and an indicator operatively coupled to the airflow detector, the indicator being configured to emanate an indication that the airflow detector has detected an airflow. 
         [0014]    An advantage of the present invention is that the functioning of a vacuum valve can be determined at a distance from the vent pipe, no longer requiring a person to listen for the flow of air 
         [0015]    Another advantage of the present invention is that the airflow monitor is easily installed in existing vent pipes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0017]      FIG. 1  is a schematical view of a vacuum sewer system using an embodiment of a valve monitoring system of the present invention; 
           [0018]      FIG. 2  is a closer side view of the valve monitoring system of  FIG. 1 ; 
           [0019]      FIG. 3  illustrates a closer view of the airflow monitor or valve monitoring system itself of  FIGS. 1 and 2 ; 
           [0020]      FIG. 4  is a partially sectioned side view of the airflow monitor of  FIG. 3 ; 
           [0021]      FIG. 5  is a partially exploded schematical view of parts of the airflow monitor of  FIGS. 1-4 ; and 
           [0022]      FIG. 6  is a block diagram of the functional components of the airflow monitor of  FIGS. 1-5 . 
       
    
    
       [0023]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    Referring now to the drawings, and more particularly to  FIG. 1 , there is shown a home collection system HCS coupled to a central sewer system CSS. Multiple home collection systems HCS are coupled to the central sewer system CSS. An airflow monitor  10  or vacuum valve monitoring system  10  of the present invention is installed in a typical vent pipe  12  connected to a holding tank or sump HT. Airflow monitor  10  is installed through a sidewall of vent pipe  12  and may be glued in place or may be mechanically secured, for example by being threaded thereto. 
         [0025]    Central system CSS includes a vacuum system that provides a vacuum in pipe P. When the level of wastewater in holding tank HT achieves a predetermined level then valve V opens and the vacuum in pipe P pulls the wastewater from holding tank HT to central system CSS. Air flows into holding tank HT by way of vent pipe  12  until valve V closes when the level of wastewater in holding tank HT is lowered. Airflow monitor  10  detects the flow of air through vent pipe  12  and provides a signal when the airflow is occurring as discussed herein. 
         [0026]    Now, additionally referring to  FIG. 2  there is shown a closer view of vent pipe  12  with airflow monitor  10  installed therein. Airflow monitor  10  can be easily installed in existing vent pipes  12  by drilling a hole through the side of pipe  12  inserting monitor  10  from the inside of pipe  12  through the hole and threading a nut on the threaded portion of monitor  10 . 
         [0027]    Now, additionally referring to  FIGS. 3-5 , there are shown more details of airflow monitor  10 , which includes a base unit  14 , a securing means  16 , and a light diffuser or refractor  18 . 
         [0028]    In base unit  14  there is an LED light  20 , a battery pack  22 , a Reed switch  24 , a magnet  26  and a flapper  28 . When an airflow moves past flapper  28 , which may be a diaphragm  28  it cause magnet  26  connected thereto to move, which in turn causes reed switch  24  to electrically close and conduct electricity from battery pack  22  to LED light  20 . Reed switch  24  along with magnet  26  and flapper  28  can be considered a sensor, which may be an integral unit. LED light  20  may be constantly illuminated or blink in a specific pattern to indicate the flow of air. This then allows the leaky valve V to be easily found and corrected. 
         [0029]    During normal operation whenever the valve V is activated and there is an airflow then LED light  20  will illuminate. Since normal operation will then have the valve closing in a few seconds the constant activation (whether blinking or solidly illuminated) provides an alert that maintenance is needed. 
         [0030]    It is also contemplated that a timing circuit  30 , as depicted in  FIG. 6  may delay the activation of light  20  until a predetermined time, such as 20 seconds, 30 seconds or 1 minute, or some other predetermined time has passed. This allows airflow monitor  10  to never illuminate indicator  20  during normal operation of the sump and valve V. 
         [0031]      FIG. 5  functionally illustrates the circuitry that effects the action described above. Here diaphragm  28  is pivotal about line  30 , so that airflow will cause diaphragm  28  to move about pivot  32  to cause the activation of airflow monitor  10  as described above. 
         [0032]    It is also contemplated that a solar power cell may be used to provide power to battery pack  22  to maintain the operating condition thereof. It is further contemplated that some alternative alerting technique may be used instead of or in addition to light  20 . Even an infrared light  20  or some light or other signal not visible to humans might be used to send a signal that is then detected by use of a known detection device. 
         [0033]    It is further contemplated that airflow monitor  10  would remain inactive until remotely triggered to function by way of a remote control not shown. 
         [0034]    While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Summary:
A vacuum sewer system including at least one home collection system, a central vacuum system coupled to the home collection system and a vacuum valve monitoring system coupled to the home collection system. The vacuum valve monitoring system has an airflow detector and an indicator operatively coupled to the airflow detector, the indicator being configured to emanate an indication that the airflow detector has detected an airflow.