Abstract:
A method for detecting and reporting fluid leaks in a distribution network, particularly in condominium water or gas distribution networks, the method providing the steps of: acquiring at a preset rate statistical samples related to the extent of the water flow in input to the network; acquiring a variation coefficient which indicates the characteristics of the samples over a set time interval; comparing the variation coefficient with a preset reference value to identify a situation of fluid leak or of normality within the network; reporting the situation to monitoring devices.

Description:
The present invention relates to a method for detecting and reporting leaks of fluid in distribution networks, particularly in condominium water or gas distribution networks, and to an apparatus for performing the method. 
   BACKGROUND OF THE INVENTION 
   As is known, water distribution networks, due both to the aging of the pipes and systems and due to faults caused by accidents of various kinds, are subject to water leaks which can be frequent and more or less substantial. 
   In particular in the case of civil buildings, water leaks are particularly onerous, not only from an economic standpoint due to the waste entailed by such leaks but also because by being often hard to detect they can cause the onset of damage to adjacent buildings and dwellings and affect, in the most severe cases, both the structures of the buildings (for example the foundations) and the infrastructures (for example, courtyard paving, road paving, footpaths, et cetera). 
   The damage caused by water leaks, in addition to the damage mentioned above, involves another aspect which is certainly not secondary, i.e., the ethical one. The leaks of water distribution systems in fact waste an enormous amount of water, i.e., of a resource of primary importance which is not renewable and for which the need for active protection is ever more clearly felt at all levels. 
   The problem of water leaks is even more severe in cases in which dwellings are left unattended for long periods, when due to the lack of constant and frequent monitoring the abnormal consumption of water is detected when the harmful effects have already become apparent. 
   Water leaks are currently detected rather empirically by making a comparison between normal consumption of the user and a consumption which is believed to be abnormal. In this regard, it should be noted that for example condominiums usually have a single connection to the public water distribution network and the total withdrawal of water (i.e., the amount consumed by the dwellings) is quantified by a meter which is installed at the entrance of the supply. 
   If indication devices are not provided, any leaks are diagnosed by comparing water consumptions between two billing periods. 
   It is evident that if the consumption comparison times are widely spaced, the accumulated economic damage can be substantial. 
   Similar drawbacks are observed in gas distribution networks, with the addition of the danger of explosions. 
   SUMMARY OF THE INVENTION 
   The aim of the present invention is to provide a method which allows to diagnose the occurrence of water leaks in a much shorter time than required with current procedures, so as to reduce material and economic consequences. 
   Within this aim, an object of the present invention is to provide a method which is highly reliable in operation and in particular is insensitive to inappropriate physical parameters such as for example temperature variations of the water flow. 
   Another object of the present invention is to provide an apparatus which is easy to install in any civil and industrial distribution system and is capable of providing correct reporting of consumption anomalies to the personnel assigned to monitoring the water or gas network. 
   This aim and these and other objects which will become better apparent hereinafter are achieved with a method and an apparatus for performing the method whose characteristics are defined in the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further characteristics and advantages of the invention will become better apparent from the following detailed description of an embodiment thereof, illustrated by way of non-limiting example in the accompanying drawings, wherein: 
       FIG. 1  is a block diagram of an apparatus provided with a computer according to a first version for processing the values detected at the input of a water distribution network; 
       FIG. 2  is a block diagram of an apparatus provided with a further version of the computer. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In the accompanying  FIG. 1 , the reference numeral  1  designates a diagram of an apparatus for detecting and reporting water leaks in a condominium water distribution network. 
   The apparatus  1  is composed substantially of three assemblies which are functionally mutually associated, and specifically: sample acquisition means, such as a flow transducer  2 , a processing unit or computer  3 , and an indicator or reporting means, such as a reporting device  4 . 
   The transducer  2  is conveniently preset to sample the flow, i.e., acquire samples of the extent or quantity of the flow at each instant. Advantageously, the acquisition rate of such samples is for example approximately 1 second, in order to avoid delays in detecting variations in the water flow. 
   The signal processed by the transducer  2  is sent to the computer  3 . The characteristics of the signal are correlated to the consumption habits of the user and to any consumption caused by water leaks. Therefore, in normal operating conditions (i.e., in the absence of water leaks), high flow differences occur during the day. 
   The computer  3  comprises a coefficient acquisition means constituted by a threshold comparator  5 , which detects whether the samples of flow acquired by the transducer  2  have a value which is higher or lower than a preset threshold value, which is contained in a memory  6  and indicates the minimum extent of the water leak that the apparatus is capable of detecting. 
   The comparator  5  is connected to a detection unit which is constituted for example by an incremental counter  7 , which counts the number of consecutive times for which the comparator  5  has detected the presence of a water flow which exceeds the preset threshold value. Every time a flow sample detected by the transducer  2  has a value which is lower than the threshold valve of the memory  6 , the counter  7  is reset. 
   Vice versa, the number of consecutive samples of flow exceeding the threshold value of the memory  6  is totaled by the incremental counter  7  and sent to a comparison means constituted, for example, by a second comparator  8  and compared with a preset reference numeral, which is stored in the memory  9 , and the result indicates an abnormal flow situation. 
   If this comparison shows that the reference numeral stored in the memory  9  is smaller than the numeral at the output of the counter  7 , the comparator  8  recognizes this situation as abnormal and due to a water leak. In this case, the leak is reported appropriately by reporting means, such as the reporting device  4 , to the personnel assigned to monitoring. This may be carried out, for example by sending signals by means of a transmission (reporting) device constituted by a GSM modem or other suitable known transmission devices. 
   As can be seen, the described invention perfectly achieves the intended aim and objects. The important advantage of the proposed solution lies in that any malfunctions in the water network can be diagnosed more rapidly than with traditional empirical methods. 
   Further, diagnosis of any malfunctions by statistical identification of the abnormal flow caused by water leaks has the considerable advantage of requiring the use of a single flow transducer and therefore of having cheaper material and installation costs than traditional systems which, for example in a condominium, entail a comparison between the incoming flow and the sum of the outgoing flows. 
   The flow and count threshold values stored in the memories  6  and  9  are characteristic values of the installation site and are correlated respectively to the extent of the minimum flow of a leak which can be recognized by the device and to the maximum time within which said leak will be recognized. 
   However, it is possible to use a plurality of processing units such as the one described which work in parallel but have different pairs of threshold and count values; this is done in order to recognize substantial leaks in a shorter time and more modest leaks over longer time periods. 
   In practice, the method according to the invention and the apparatus for performing it are susceptible of numerous modifications and variations, all of which are within the scope of the appended claims. 
     FIG. 2  illustrates a solution in which the computer  3  is preset for a statistical analysis of the sampled flow values by using the deviation, understood as the difference between a value assumed by the variable flow and a fixed value of the flow. Conveniently, a mean value is taken as a fixed value, and in order to have a measurement of the scatter of the flow variation around the mean value, the variance or mean square deviation s(x) is considered, defined as a weighted square mean of the deviations from the arithmetic mean M(x), which substantially expresses the error that is made by assuming the mean value instead of the detected values. From what has been described it is evident that if a normal flow is assumed, the mean square deviation s(x) will reach higher values, while the mean M(x) will remain at low values. 
   In the presence of a water leak characterized by a slow flow variation, i.e., extended over time, the mean square deviation s(x) will instead tend to zero, while the mean value M(x) will be high. 
   The computer  3  therefore comprises a module  10  ( FIG. 2 ) in which the variation coefficient d(x) is calculated, said coefficient being understood as the ratio between the mean square deviation s(x) and the mean M(x), acquired over a preset time interval. The comparator  5  then compares the variation coefficient d(x) with a reference value which is stored in the memory  6  and is determined, as mentioned, in relation to the characteristics of the installation site of the transducer or by means of a self-learning step. 
   The output of the comparator  5  is connected to a detection unit  11 , which is constituted by a timer which measures the time interval within which the output of the comparator  5  identifies a value of the variation coefficient d(x) which is lower than the reference value of the memory  6 . The second comparator  8  checks that the time interval measured by the timer does not exceed a preset value, and if this occurs, its output activates the reporting device  4 . 
   A simplified method is based on the consideration that for a typical behavior of a normal flow, i.e., without water leaks, since the variation coefficient d(x) is normally higher than the mean value M(x), the likelihood that the value of the flow will drop to zero or in any case below the minimum threshold value of the leak that one is interested in identifying, over a sufficiently long period of observation, is high. On the contrary, in the presence of a leak the value of flow will never drop below this value. 
   The method is characterized in this case by the presence of a timer which sets a time within which the identification of the condition of the flow below a preset threshold value must occur, so that if the transducer determines that there is a condition of a lower flow within the preset time, the timer is reset and the absence of leaks is ascertained. If instead the intended time elapses without failure of the threshold condition, the abnormal situation which can be traced back to a leak is identified and therefore reported by means of a GSM (Global System for Mobile communications) modern or other monitoring device to the monitoring personnel. 
   It should be noted that the described method can be applied similarly for detecting gas leaks. 
   The disclosures in Italian Patent Application No. BO2006A000463 from which this application claims priority are incorporated herein by reference.