FI84939B - FOERFARANDE FOER LOKALISERING AV LAECKSTAELLEN I VATTENLEDNINGAR UNDER JORD. - Google Patents

Description

1 84939

Method for locating leak points in underground water mains

The invention relates to a method for determining leakage points in underground water mains by separating or bypassing a pipe branch to be examined in a conventional existing water supply network and connecting a measuring device provided with a measuring pipe to the separated pipe branch.

In order to determine the leakage points of underground water pipes according to location and / or size, it is known to close the pipe branch in question with a shut-off valve placed in the pipe branch and to pass water through a measuring device which then measures the amount of water flowing. Such a method is used, for example, in Austrian patent 56267. In order to be able to determine whether there is a leak point in the pipe branch under investigation at all, the water intake of all users must then be switched off. If the measuring device then appears to be flowing in the pipe branch under test, there is a leak in it. This previously known method has the fundamental disadvantage that the water supply of all users is cut off for the measurement time. This requires a considerable amount of workload and causes inconvenience to users in terms of housekeeping and occupation.

The invention avoids these drawbacks. The object is to find a method by which leaks 30 in underground pipelines can be determined without the user being without water for a very long time.

This object is solved as set out in claim 1.

35

The measuring device is thus provided with at least one display device (e.g. a plotter) which registers the measured values in the long term. With the exception of very 2 84939 short interruptions, the users of the branch line under study receive water continuously, even if the measurements continue. Since the measuring device regularly records the measured values with the plotter, it can be deduced from these values whether there is a leak in the pipe branch under test. The existence of a leak is reported in such a way that if the measured values do not fall to zero in the long run, there must be a leak in the pipe branch under investigation. Experience has shown that all users of the 10 pipelines will stop using them at some point, for example overnight. During these times, the measured values must indicate zero operation, otherwise the there is a leak in the pipe branch.

15 With such a method it is possible to perform the area leakage loss analysis. However, it is difficult to determine the exact location of the leak at this method.

20 The task is also to find out the leakage losses of the parts of the water supply network in absolute values by the measurement method itself (losses in m3 / h) and as relative losses, ie the ratio of the amount of water purchased by consumers to the total amount of water (losses%). In addition, the location of the leakage points of the lines 25 is done by changing the location of the measuring carriage inside the network part, whereby with a new type of method the leakage points and the condition assessment of the lines, valves and water posts can take place faster and more reliably.

This task is solved by such a method, which is characterized in that a pressure-changing component is connected to the measuring tube before the measuring device is put into operation and that the change in flow noise due to leaks in the shut-off slides 35 is determined.

The method is further characterized in that after determining the water losses of the pipe 3 84939 to be examined, a pressure-changing component is attached to the measuring pipe and that the change in noise caused by pipe leaks is determined.

Such a method is further characterized in that, while the water losses are determined by flow-through measurement, the pressure conditions of the closed block are determined and possibly the operating pressure of the closed block is changed.

10

It is therefore essential that the pressure-changing components are installed in the measuring pipe in order to achieve an effective location of the leakage by listening monitoring of the pipeline network and that both absolute leakage losses 15 and also relative leakage losses are determined statistically using electronic data processing.

Reference: 20

The following classification of concepts is used for the networks under study: Wire-block-area-network.

According to DIN 4046 (Deutsche Industrie-Norm), 25 losses are divided into "non-actual" losses (uncontrolled consumption, measurement errors) and actual losses (leaks, piping losses).

High "actual" losses not only indicate pipeline failures, hardware damage, and leaky connections, but appear to be an additional commercially unprofitable expense item.

Leakage detection and location in the aqueduct-35 network is still difficult today despite electronic leak detection with geophones, as side noises, piping material quality, shape of damage sites, ground quality and pressure used in network survey 4 84939 are affected and other difficulties often occur from time to time. Systematic examination of the network does not always produce the desired result, because without knowledge of the actual situation it is not possible to hear the difference between 5 undamaged and damaged pipelines.

Leaking pipes are not easily identifiable so that the actual comparison before and after the network inspection is not possible.

The present invention will now be described in more detail by way of an exemplary embodiment. The features and advantages of the invention will become apparent from the drawings and their explanations.

15 Figure 1 schematically shows a piping network from which one block has been separated

Figure 2 Schematic representation of the structure of the measuring pipe 20 Figure 3 Schematic representation of the piping

Figure 4 Structure of the measurement site

Figure 5 is a measurement curve obtained with a measuring device for water flow 25 with the devices of Figures 1, 2 or 4

The water supply network to be examined consists of pipes 1 branching from pipe branch 23 and can be separated into separate blocks by means of closing devices 30, 14, 15. The size of the sector (range 17) is defined in such a way that, during the minimum operation, no more than instantaneous zero operations occur in a period of 15 to 20 minutes. This means that:

The water supply network with pipes 1 is separated into an area 17 by closing the shut-off slides 14 and 15. From outside the closed area 17, the amount of water that would otherwise flow into the area 17 through the pipe branch 23 is taken from the water post 3 and passed through a measuring carriage 16 containing a measuring device. to measure pressure.

5 From the measuring trolley, water continues to flow through the measuring pipe 11 and the water post 12 to the water supply network of the closed area 17. In addition, the measuring tube 24 is connected to the water post 13 (cf. Fig. 2). Thus, the measuring carriage 16 and the measuring means located therein 10 measure the amount of water entering the closed area 17.

The entry of water into the closed group of pipes now takes place through the measuring pipes 10, 11 and the outlet of water 15 through the measuring pipe 24. In each measuring pipe 11, 24, the amount of water flowing through is measured and checked. From the difference between the amounts of water flowing through or the amount of water used, it can be deduced whether or not there is water damage in the closed pipe group. 20 days of continuous longer-term monitoring can be used to monitor water use habits. If a large leak is now detected inside the closed area by abnormal water consumption and excessive separation of incoming and outgoing water, then the fault location 25 can be limited by reducing the closed pipe group by closing the necessary number of slides so that the closed pipe group is limited to e.g.

For example, by closing slides other than 2, 14, 15 in the region 17, smaller sub-areas can be obtained, for example along the line 20 by closing the closing slides 21, 22.

35 If the water volume drops significantly, then the fault is now outside the enclosed area, unless the water volume decreases, the fault is inside the enclosed area.

6 84939

By corresponding restriction, it is possible to determine relatively quickly and easily in which branches of the pipe the fault locations are located. Due to the fact that the pipeline network is constantly under pressure and only short-term interruptions due to the closure of the pipes have to be made, there are practically no disturbances in the water supply. The time required to study the pipeline network is approximately 1/3 of the time previously required to conduct the study.

10

It was previously shown that the pipe 1 in the pipe branch 23 going to the user was closed (with a closing slide 14) and the water supply to the user takes place by means of measuring pipes 10, 11, 24 and a measuring means connected to them (measuring carriage 15). This method assumes that the closing members (closing slides 14, 15) function properly and that no side flow takes place through the normal pipe branch 23. If these shut-off slides 14, 15 are now opened during the measurement and the measuring pipes 10, 20 11 and the associated measuring means (measuring carriage 16) act only as a side flow, this results in a distribution of water flows according to Kirchof's law, where the amount of water flowing is directly proportional to the pipe branch 23 and the measuring pipe. 10, 11 split-25 into which, given the Reynolds number. The values measured from the side flow are run to a minicomputer programmed according to the diameters of the pipe branch 23 and the measuring pipes 10, 11, the Reynolds number and the pressures of the pipe branch 23 and the measuring pipe 10, 11.

In this way, the amount of water flowing through the pipe branch 23 can be measured with sufficient accuracy without having to cut off the water supply at all. Another advantage of this system is that the amount of water flowing through the measuring tube 10, 11 and the associated measuring means (measuring carriage 16) is substantially lower than before. This results in greater mobility and a reduction in the operating costs of the measurement method.

7 84939 These obtained measurement results can also be obtained on the plotter 8 as can be seen from the electronic system described later.

5 Figure 2 shows the measurement system. The fastening pieces 9 'and 9' 'fasten the measuring pipe 10, 11 to the side pipe or to the water posts 3, 12 and it then acts as a flow pipe. A similar measuring tube 24 is attached to the (return) water post 13. The water flowing from this tube 10 can be utilized. The pressure gauge 5 monitors the water pressure. Two water meters or measuring means T, Τ 'for measuring the amount of water flowing per unit of time are placed in two parallel pipe branches one below the other. The function of the stopcocks 6 15 is to connect a second water meter if desired. The water meter 7 'measures a larger amount of water with relatively low accuracy, the water meter Τ' measures a smaller amount of water with better accuracy. The plotter 8 is connected to a measuring means for measuring the amount of water flowing in the time-20 unit. It accurately shows consumption. This plotter 8 is a suitable multifunction plotter which records the water entering and returning from the network. Also preferred may be a plotter that shows the difference between water entering and returning directly to the network. Suitable measuring devices which, for example, show the through-flow rate.

In the system according to Fig. 3, the water is pumped by means of a pumping station P to a tank R located higher. The measurements take place in the sauna in the same way as in Fig. 1, i.e. the slides are closed and the water posts 1H-12H are connected. The measuring device DM is similar to Figure 4, with two pressure gauges 5 'and 5' '. 35

They can be used to monitor whether the section of pipe to be examined is depressurized after closing the skate V and whether water is leaking from the defective valve. Otherwise, the numbers β 84939 correspond to the numbers in Figure 2. There is a certain time delay depending on the physical factors between the incoming and outgoing flow, which can interfere with the parallel measurement. Therefore, it is preferable to synchronize the inlet and outlet openings. This is done by a pneumatic pressure wave applied to a pressurized water column at the inlet of the pipe and which is at the end of the pipe after a certain time. This allows the start-up of the measuring device to be timed.

10

In another embodiment of the invention, the flow time between measurements is determined and its effect is eliminated. This is as follows: 15 It has previously been emphasized that it would be advantageous for the measuring means at the inlet and outlet of the measuring range to be synchronized in order to obtain small measurement technical differences. Using digital registration, the measurements taken at the beginning and end of the measurement interval 20 can be synchronized.

Therefore, it is necessary to measure the flow rate and the digital register installed at the beginning of the measurement interval starts operating after the time delay determined from the flow rate. Thus, the input and output signals are in a similar relationship to each other and can thus be compared.

By using a dual digital register or two separate digital registers into which the measured values 30 come from the beginning and the end of the measuring interval, the time difference caused by the flow rate can be eliminated.

By combining the electronic devices described above with 35 measuring units, the following advantages are obtained: a) Previous visual observations of the plotter 8 measurement curve are omitted and replaced by a digital 9 84939 display.

b) Automatic measurements or automatic interpretation of measurements.

5 c) Leaking slides (closing slides 14, 15) cannot interfere with the measuring method.

(d) Staff reductions.

10 e) Reduced space requirements and easier placement of measuring devices.

Consistent use of the idea of the invention provides the following possibilities.

In the closed pipe branch, water is passed from the operating pressures through the water flow counters (water meters 1 ', Τ') from another pipeline network (water post 20 3). At the end of this closed pipe branch, the drain valve (water post 13), to which the flow rate counter is also connected, can take a precisely defined amount of water. Thus, with unused pipes, the inlet and outlet of both flow-through counters 25 must show the same value. Both measured values are obtained digitally in liters or m3 / s or m3 / h and the corresponding values for plotters. If there are leaks in the closed pipe or if it has normal use, a difference will occur between the inlet and outlet flows. Pipe damage appears as a continuous same difference. Short-term use is well visible on the plotter. Both values of the flow-through water counters can be connected to each other by an electrical application, thus creating the possibility that only the difference can be revealed. It is therefore appropriate to equip this measuring point with a plotter plotting three values, giving the following values simultaneously: 10 84 939 a) inlet flow rate b) outgoing flow rate c) difference of the previous 5

With the measuring means of the measuring carriage 16, the measuring curve according to Fig. 5 could be obtained. The abscissa is the measurement time, while the coordinate is the amount of water entering the network block at the corresponding time. Curve 10 shows the maximum and minimum, and in particular shows that during lower use, the consumption does not momentarily drop to zero, because the inflection point 18 of the curve is not even close to the abscissa. By definition, there is no damage to the measured pipe branch when the amount of incoming water 15 drops to zero at least momentarily. Based on this, the existence and magnitude of water pipe damage in the pipe branch can be ascertained by the connecting line of the lower inflection points. If the lower inflection points of the flow-through curve are combined and a horizontal line is obtained from this, then the amount of loss can be read directly.

The measurement curve in Figure 5 means that there are actual and non-actual losses in the examined area 17. The inflection points 18 are connected by a line 19 delimiting the dashed area, the coordinate values of which give the magnitude of the actual and non-actual losses of the area 17. In the following, for the sake of simplicity, it is assumed that the non-actual losses (control-30 warp consumption, measurement errors) are so small that the hatched area in Figure 5 is proportional to the actual losses (leaks, piping losses) over the entire measurement period.

35 It is essential here, however, that when in the network block (area 17) a large consumer with a constant consumption (eg a production plant), this consumption must be known in order to eliminate the water consumption of this user during the measurement period. The high consumer usage characteristic curve can be determined before the measurement using the purchase account as a basis.

5 During the measurement, the counter and the plotter obtain several turning points 18 from the flow of the network block, the horizontal association line of which separates the loss fraction (taking into account the continuous consumption) and the actual use. Simultaneously with the flow measurements 10, the pressure conditions are registered by a pressure recording device.

It is essential here that if the method described above is not used, in which the shut-off slides 14, 15 are left open and the parallel flow takes place along the pipe branch 23 and the measuring pipes 10, 11 according to Kirchoff's law, the shut-off slides 14, 15 responsible for limiting the area must be carefully closed. In order to guarantee such a functional condition, it is essential that these 20 closing slides 14, 15 are examined before carrying out the flow measurements. This is recommended when, in accordance with the permissible operating pressure, the pressure in the closed area 17 is raised and lowered by means of a pressure-changing component located in the measuring carriage 16. 25 Changing the pressure results in a pressure difference across the closing slide, which results in noise amplification in the event of a fault.

If the losses in area 17 according to the curve in Figure 5 are determined, the measuring range can be reduced by changing the limits (or moving the measuring trolley) to individual pipes or part of the range. For example, by closing the closing slides 21, 22, the larger area 17 can be divided into a smaller area 20. Correspondingly, the location of the damage-35 takes place with a geophone.

The connecting line 19 of the lower inflection points 18 and also its distance from the zero plane (abscissa) are the decisive results of i2 84939 and the interpretation of the measurement results takes place on the basis of the curve drawn by the plotter 8. Interpretation of the results gives: 5 a) losses: yes or no b) magnitude of losses To find out both of these results, the electronic device 10 described below can be used to replace the previously necessary plotter 8 and plotter curve examination.

The flow relative to the total flow, which otherwise flows through the plotter 8, in this case flows through the digital register 15. The pacemaker is used to record the measured values at specified intervals and record them.

It is then preferred to select a time interval of about 1 minute to 20 ti. This means that about 60 measured values can be registered in one hour.

The microprocessor arranges the individual measured values in a specific chronological order and tests the correspondence of the 25 lower inflection points. The microprocessor itself is programmed in such a way that when the existence of a line indicating a horizontal loss amount has been established, the amount of loss is obtained by means of an analog and digital instrument or a printer.

30

By using a microprocessor in the above-mentioned measurements, the previously necessary plotter 8 can be replaced and the desired data can be read digitally. This law allows for automatic and simultaneous monitoring of several measurement sites, resulting in significant cost savings in personnel costs.

i3 84939

Distributed interpretation of measurements 1a Differential pressure measurements

There is a possibility of abandoning the centralized interpretation of the measured values and instead installing a two-part receiver of the measured values in the incoming and outgoing flow. This is especially advantageous when you need to work more than 24 hours. In this case, a simple 10 24-hour plotter is useful (e.g., a rotary plotter) that can record analog or digital measurement values. After 24 hours, both measurement curves can be compared and interpreted. This method seems particularly important 15 when the simultaneous use of several such plotters allows a larger network to be interpreted at one time, thus significantly reducing costs. In parallel with such flowmeters equipped with simple plotters, it is possible to obtain pressure fluctuations with a similar plotter operating for 24 hours. In principle, this can be exactly the same type of plotter as in flow measurement. Systematic pressure monitoring in a given pipe branch, including the user, can accurately detect damage (also in the connecting pipes of the house) and pipe constrictions. Of course, these pressure receivers must be equipped with an adjusting screw so that all the pressure gauges in the circuit can be normalized.

30 The transfer of measured values is omitted when the main measuring instrument is connected between the inlet and outlet pipe. During longer observations or when there is no possibility to perform such a connection, the measured values 35 of the at least one measuring point must be transferred to the exchange. The center is located, for example, in a measuring trolley. In addition to the usual conductors, other methods can also be used for this, for example a ferrolux device which transmits and receives impulses via the i4 84939 water supply network.

The differential pressure or flow rate difference method aims at continuous monitoring of the water pipes. Above all, a digital comparison of both measured values is suitable for this, in which case the first counter pulses are compared with the second counter pulses. If the difference exceeds a predetermined preselected value, a signal may be sent which triggers the automatic disconnection of the alarm device 10 or the damaged section.

It is also possible that all main pipes in the water supply network will be inspected in this way. All main pipes can then be marked on the control panel with lamps which, when the pipes are in proper condition, all show a green light, but the damage to a given pipe is indicated by a red light.

The possibility of pumping water from the operating pressures from the second piping network into the closed pipe also offers the possibility of conducting ultrasonic pulses to this pressurized water column, e.g. with a suitable ultrasonic transducer, which can be used 25

Approximate calculations have shown that similar oscilloscopes can be built at relatively low cost.

In addition, with the sound transducer installed in this water column, the above-mentioned water column can be kept under vibration so that, for example, possible plastic pipes can be located. In this case, it is assumed that the water column is made to vibrate by a sound transducer, 35 and these vibrations are transmitted from the wall of the pipe to the surrounding soil, so that they can be received on the ground by a microphone.

is 8 4 9 39

Absolute and relative water loss analysis

In the past, however, the losses of a water utility could be determined by comparing the amount of water consumed with that purchased by consumers 5, ie the difference between the two amounts is an absolute loss. However, this determination could only be made ex post on the basis of annual consumption reports, so that the water utility was only aware of the annual losses, but not of the losses of the smaller 10 time units. It is an object of the present invention to provide a method for determining the statistical distribution of absolute and percentage water losses in a closed block.

The method according to the invention is characterized in that the absolute water loss is first determined by generating the difference between the amount of water supplied by the water utility and the amount of water used by the users of the closed area 17, minus the uncontrolled consumption and measurement errors. The total consumption of the closed area 17 is obtained by summing the amounts of water used by individual consumers. Furthermore, the method is characterized in that, secondly, the instantaneous water loss is determined by flow measurement and that this water-25 loss is converted (interpolated) for the same period as the absolute water loss (e.g. for a period of 1 year).

It is therefore essential to compare the measured water losses of the network block in a suitable form in the computer with the water usage amounts. In this way, a statistical distribution of the absolute and percentage losses of the network is obtained.

35 It is also essential in the device according to the invention that the following additional information is obtained with the water loss data obtained by parallel flow measurement with the measuring trolley principle: 5 i6 84939 Variation of losses in the network block (area 17, 20) or network area depending on operating pressure (eg expanding tank pressure zone).

Investigation of the roughness of a single pipe by several standard water intakes along the pipe in chronological order.

10 Determination of the efficiency of an individual pipe by pressure drop at the end of the pipe up to the minimum pressure through the water intake of the water post and simultaneous flow measurement.

15 Follow-up of corrections made by flow measurement.

Water losses in a given unit of time (eg calendar year) are broken down as follows: 20 water supply minus water sales minus an estimate of "non-actual" losses.

25 Knowing the distribution of losses in a water supply network can be used in operation, planning and statistics.

Such a water loss analysis can be performed as follows:

Sales volumes for each network block are collected from consumption addresses based on the current usage meter reading. At the same time, data are collected on the 35 large consumers that can affect the flow measurement.

The measured loss amounts for each network block are recorded, calculated over a period of meter reading periods, and compared to sales volumes.

If the amount of losses is calculated and taken from the re-measurements carried out to verify the results, information is obtained on the expected change in total water loss (eg in% or m3 / year) in the network or network area.

10 The measuring trolley 16 for water loss analysis performs the following tasks: a) Forms a unit in which various water technical measuring instruments and their mechanical or hydraulic-electrical converters are assembled.

b) Forms a unit in which all electronic display devices and recorders are assembled. Serves as a location for a radio device that communicates with 20 assistants.

c) Acts as a power distribution center, keeping all measuring and recording equipment in continuous operation.

25 d) Provides faster and more mobile use of all measuring and recording instruments.

e) Provides the possibility to transfer additional means, e.g. pipes, tools 30.

f) Allows storage of pressure changing devices.

35 g) Acts as a weather protector under occupational safety and health legislation ie 84939

In particular, the following groups can be distinguished from measuring and recording devices: a) Flow flow measuring instrument, including a transducer for 5 measurands.

b) Pressure measuring device with transducer.

10 c) Electronic measuring and recording devices for both flow measuring equipment and pressure measuring equipment.

d) Power supply, control panel for optional connection of 15 private measuring points and simultaneous monitoring of all technical aspects of measurement.

e) Mobile and portable measuring instrument for accurate piping damage determinations in accordance with the sound and geophone principle propagating in a solid body 20.

Pressure transducers

Pressure-increasing measures are necessary in order to test slides, water poles, reinforcements during use. Significant improvements can also be achieved by increasing the pressure in connection with the accurate determination of the leakage point of low-pressure pipelines.

30 In this case, it is especially necessary: a) A pneumatic cylinder filled with compressed air with a pressure regulator and a valve.

35 b) Electrically controlled pump for increasing pressure.

19 84939

Measuring equipment and instruments Water-technical part: 5 The rear part of the water-technical measuring carriage 16 has inlet and outlet connection lines equipped with fast-acting ball valves. The connection between the two lines is a Woltmann counter through which the entire amount of water must flow and thus 10 be measured.

A pressure measuring device is also connected to the same water circuit to determine the pressure conditions and pressure changes in the closed pipe.

15

The flange of the connection line of the pump for increasing the pressure is installed close to the outlet connection line. The pressure rise generated by the pump is primarily used to inspect slides, water posts and also pipes, as leaks are generally pressure-dependent and no significant damage is seen at low pressures.

The connection of compressed air also takes place in the vicinity of the connection piece 9 '' of the outlet connection-25 line. With this compressed air, pressure testing of the pipe can be performed on the one hand and the damage search on the other hand by increasing the pressure.

30 Electronic measuring 1a registration components

The measurement currents proportional to the pressure and flow produced by the transducer can be taken as follows: 35

A) pressure on the plotter I

B) pressure on the plotter II

C) flow to plotter I

2 ° 84939

D) flow through to plotter II

Using a multifunction plotter, pressure and flow can be plotted on a recording strip.

5

Thus, it is possible to determine and interpret the connection and dependence of pressure or flow changes from a measurement point of view. In this case, in particular, in order to determine the lower inflection points of the "zero-flow" range, in order to determine the leakage losses, special measures must be taken in order to obtain a higher accuracy.

It is essential in the method according to the invention that network areas and network blocks (residential areas, downtown areas) with a very different consumption structure can be analyzed reliably.

20

Claims (13)

2i 84939 A method for locating leakage points in underground water mains, in which the pipe or piping (1) forming the network block (17) to be examined is closed by normally sliding slides (14, 15) from a normally operating water supply network and the excluded pipe / pipeline (1) via a measuring pipe (10, 11, 24) comprising at least one water flow measuring means (7 ', 7 "), whereby the water supply to the consumers operates without interruption and the amount of instantaneous mini-consumption is determined, characterized in that the pressure in the pipe / pipe (1) is recorded by a pressure gauge (5) connected to the measuring tube as is known per se, and the measured pressure and consumption values are recorded in the long term by a multifunction plotter (8) or a similar device such as a digital recording device against the instantaneous minimum consumption curve. the turning points 2Θ (18) are connected on the connecting line (19) and if the connecting line (19) is substantially horizontal and differs from the horizontal line corresponding to zero consumption, the leakage is estimated from the difference between the water consumption value corresponding to the connecting line (19) and the value of this . Method according to Claim 1, characterized in that the pressure of the pipe to be examined is increased. Method according to Claim 1 or 2, characterized in that a component which changes the pressure 22 84939 is connected to the measuring pipe (11) before the measuring means is introduced, and that the change in flow noise due to leaks in the closing slides (14, 15) is determined. A method according to claim 1, characterized in that after determining the water losses of the pipe to be examined, a pressure-changing component is attached to the measuring pipe (11) and that the change in noise caused by leaks in the pipe (1) is determined. Method according to Claim 1 or 2, characterized in that the determination of the loss by means of the measuring means and the localization of the fault by examining the change in the flow-through noise take place simultaneously. Method according to Claim 1 or 2, characterized in that the determination of the loss by the measuring means and the localization of the fault by examining the change in the flow-through noise in time follow one another. Method according to one of Claims 1 to 6, characterized in that the water inlet 25 of a user in a closed network block who has a constant constant water consumption during the determination of water losses by means of flow measurement is closed or that this consumption is determined. Method according to one or more of Claims 1 to 6, characterized in that, while the water losses are determined by a flow measurement, the pressure conditions of the closed block are determined. 23 84939 Method according to one or more of Claims 1 to 6, characterized in that the operating pressure of the closed block is changed while the water losses are determined by a flow measurement. A method according to claim 1, characterized in that the pressure of the pipe to be examined is changed by opening the water intake point of the closed network block (pressure drop at the end of the pipe). A method according to claim 1, characterized in that the measuring tube (10, 11) and the measuring means (measuring carriage 16) attached thereto are in parallel with the closing slide (14) belonging to the closed area 17 and that the flow through the open tube branch (23) ) is calculated according to the inlet flow of the pipe (1) to be measured. A method according to claim 1, characterized in that in order to synchronize the measuring means of the inlet pipe (11) with respect to the measuring means of the outlet pipe (24), a pneumatic pressure wave is applied to the inlet measuring pipe. A method according to claim 1, characterized in that in order to synchronize the measuring means of the inlet pipe (11) with respect to the measuring means of the outlet pipe (24), the flow rate is measured and the digital register installed at the beginning of the pipe (1) starts only after a time delay. 24 84939 Patentkrav;