Detecția acustică distribuită (DAS)

Este o tehnologie care utilizează cabluri de fibră optică pentru a detecta sunete și vibrații pe distanțe lungi. Această tehnologie funcționează prin injectarea de impulsuri laser în fibra optică și măsurarea schimbărilor în semnalul de lumină reflectat cauzate de variații mecanice, precum vibrațiile sau mișcările.Cum funcționează DAS?

1.Injectarea de impulsuri laser: Un dispozitiv numit interrogator trimite impulsuri laser prin fibra optică.

2.Reflexii optice: Pe măsură ce impulsurile de lumină călătoresc prin fibră, acestea sunt reflectate înapoi de neregularitățile naturale ale fibrei (denumite puncte de Bragg).

3.Măsurarea schimbărilor: Dacă fibra este supusă unor vibrații sau presiuni externe, cum ar fi sunete, activități seismice sau alte mișcări, acestea provoacă schimbări în semnalul de lumină reflectat.

Sistemul DAS analizează aceste schimbări pentru a detecta și localiza evenimentele acustice sau vibraționale de-a lungul fibrei.

Aplicări ale DAS:

•Supravegherea infrastructurii: DAS este utilizat pentru monitorizarea conductelor de petrol și gaz, pentru a detecta scurgeri sau activități de foraj neautorizate.

•Securitate: Poate detecta și localiza intruziuni sau activități suspecte în jurul perimetrelor sensibile.

•Seismologie: DAS poate înregistra activitatea seismică și poate oferi date valoroase pentru studiul cutremurelor.

•Monitorizarea traficului: Fibra optică plasată sub drumuri poate fi folosită pentru a monitoriza fluxul de trafic și pentru a detecta accidente sau alte incidente.

DAS oferă o soluție puternică și versatilă pentru monitorizarea pe scară largă și în timp real a unor domenii variate, datorită sensibilității și capacității sale de a acoperi distanțe mari.

Detecția acustică distribuită (DAS) poate fi un instrument foarte eficient pentru detectarea pierderilor de apă în rețelele de distribuție, utilizând cabluri de fibră optică instalate de-a lungul sau în apropierea conductelor de apă. Tehnologia detectează vibrațiile și sunetele produse de apă în mișcare, oferind informații detaliate despre potențialele scurgeri.

Mod de funcționare în detectarea pierderilor de apă:

1.Detectarea sunetelor specifice scurgerilor: Când apare o scurgere într-o conductă, apa care se scurge prin fisură sau gaură produce sunete caracteristice (de exemplu, șuierat, vibrații de frecvență înaltă) și cauzează vibrații mecanice. DAS poate detecta aceste semnale acustice distincte.

2.Analizarea semnalului reflectat: Sistemul DAS monitorizează continuu fibra optică, detectând schimbările în semnalul optic reflectat de-a lungul traseului cablului. Aceste schimbări sunt corelate cu vibrațiile cauzate de scurgerea de apă.

3.Localizarea precisă: DAS are capacitatea de a localiza exact unde a avut loc scurgerea de-a lungul traseului conductei, pe baza punctului de pe fibra optică unde se înregistrează perturbarea acustică.

4.Monitorizare în timp real: Sistemul oferă date în timp real, permițând detectarea imediată a scurgerilor și intervenția rapidă pentru repararea acestora, prevenind astfel pierderi semnificative de apă și potențiale daune la infrastructură.

Avantajele DAS în detectarea pierderilor de apă:

•Acoperire extinsă: O singură rețea de fibră optică poate acoperi lungimi mari de conducte, făcând tehnologia ideală pentru monitorizarea rețelelor de apă pe distanțe lungi.

•Sensibilitate ridicată: DAS poate detecta chiar și scurgeri minore, care ar putea trece neobservate prin metode convenționale.

•Reducerea costurilor: Detectarea rapidă și precisă a scurgerilor reduce costurile asociate cu pierderile de apă și reparațiile extinse.

•Minimizarea impactului asupra mediului: Prin detectarea rapidă a scurgerilor, DAS ajută la reducerea riscurilor de eroziune, inundații și alte probleme de mediu cauzate de scurgeri necontrolate.

În concluzie, utilizarea DAS pentru detectarea pierderilor de apă permite operatorilor de rețea să monitorizeze eficient infrastructura, să identifice rapid problemele și să reducă pierderile de resurse și impactul asupra mediului.

The new tehnologys in water loess detection

Romania is one of the countries with the most drained water resources in Europe, which are relatively poor and unevenly distributed in time and space, and the usable resource is about 40 billion cubic meters, according to the World Water Day, the National Administration " Romanian Waters ". ANAR states that Romania depends to a large extent on water resources in different upstream countries, but these are not entirely usable. ANAR says that Romania's water resources amount theoretically to 134.6 billion meters (consisting of surface waters - rivers, lakes, the Danube river - and groundwater), of which the usable resource, according to the level of hydrographic basins, is about 40 billion cubic meters.

"The specific endogenous resources of Romania for the population are 1,894 m³ / year / place, Romania being one of the countries with the lowest water resources in Europe, taking into account also the exogenous water resources (representing the contributions that are made on the territory of other countries and then enters the territory of the country) - in the case of Romania Danube and watercourses in the upper Siret basin - 170 km³ / year, Romania's total water resources amount to 212 km³ / year "

Considering these aspects, the importance of reducing water losses is high and the use of any new technology makes future resources better managed in the interests of future generations.

Classical water loss localization methods provide fairly good information regarding location of losses, but require high verification times for stretched networks and has large gaps where a well-established GIS system is not available to locate the correct of the verified routes.

These methods are:

Dedication and monitoring through DMA interfaces
Monitoring the consumption and flows from the sewerage network at night in the suspect areas (use of the flowmeters at certain measuring points specially built for this purpose ... .vantages, disadvantages)
The night monitoring technology of distribution networks (monitoring with logger in system push and lift, network with direct correlation etc.) .

Traditionally water utiities designed their water networks as large interconnected and often looped systems. This design gave the system the greatest number of options for water flow and provided the utility with robust operational options.

Over time it was found that, with the flexibility of the interconnected system, there were issues in working out where the water was flowing in the network and this lead to challenges such as identifying which treatment plants were providing water to which customers and minimising unaccounted for water.

It became important to begin to introduce some more pro-active non-revenue water (NRW) management techniques to complement the more reactionary passive NRW management techniques (such as repair following reporting of the leaks). Active NRW Management was introduced where staff were deployed to identify the sources of unaccounted for water such as leaks, water theft or errors in demand prediction.

To further help the utility understand where the water was flowing in the network and how to prioritize their active NRW management, DMAs were often introduced to the water networks. DMAs are discrete isolated parts of a water network with all of the inputs from mains, and optionally outputs to other parts of the system, measured using bulk meters. There are several common DMA topologies;

Single inlet DMA

Where there is only one inlet meter into a DMA. This is preferable where possible as it minimises errors in metering and provides greatest clarity to the utility.

Multiple inlet DMA

Where for pressure or system redundancy purposes it is not possible to have single meters, multiple inlet meters may be used to feed a DMA.

Cascading DMA

Sometimes due to topology of the network a DMA or multiple DMAs may be fed by other DMAs through meters. In this situation the flow into the downstream DMA is subtracted from the flow into the upstream DMA for water balance purposes.

Pressure Reduced DMA

Where excessive pressures are present in a DMA a PRV can be introduced to reduce the pressure in the isolated DMA to reduce leaks and bursts.

Types of DMA

It is important to determine the objective of the creation of DMAs and ensure that everyone has the same expectations of the exercise. This is because the process necessarily includes making decisions that trade-off between, and prioritisation of, objectives.

DMAs are usually designed to take into account several objectives, but these objectives at times have to be traded off in a final design. Some example objectives are;

 Minimise new meter and augmentation costs

 Minimise changes to current system operations

 Optimise size of DMAs

 Maximise system operation flexibility

 Optimise pressure management

 Minimise water quality issues

 Minimise number of meters into DMAs

 Minimise cascading DMAs

A range of stakeholders typically have responsibility for these objectives and should be allowed an input into the decision making process. The stakeholders commonly include;

 Operators and Network Managers

 Hydraulic Modellers

 Capital maintenance and asset managers

In order to get results, these methods need to be combined, which require human resources and quite high times.

Noise logger

The system consists of loggers equipped with highly sensitive piezo microphones, amplifier, digitizer, memory and battery, as well as a data acquisition and processing system. Each logger has a robust, waterproof housing. By recording night-time noise, it makes it possible to detect bursts in water networks without being assisted by the operator. The loggers record the noise produced by the loss through a sensitive microphone that is connected to the digitizer amplifier. The received sound signals are recorded in the memory of the neural adaptive software both in intensity and frequency. The loggers are equipped with accumulators that give the system a high degree of autonomy over time (over 5 years of continuous operation). They are designed to be installed on hydrants, valves or other direct contact points with the pipe. Each assigns a unique recognition number, which is required in the subsequent evaluation of the data, in order to coordinate the logging with the associated measurement locations. For a successful use of the system, at least 6 logging is required. The best results are still obtained by using 15 - 45 logging. Their number determines unbound and higher measurement accuracy. First, based on the overall plan (if possible on a scale of 1: 5000), an analysis point planning is performed. It is mainly used hydrants located in accessible and important places, ie at the intersection of the pipes. Each logger is installed on each measuring point. It is advisable to install them in the metallic networks at distances up to 200 m between them, and in non-metallic networks at max. 100 m.

The area where the loggers are located is scanned with a Commander, which receives by radio link from them all the data necessary to recognize the loss. The big advantage is that the data is interpreted on-the-spot without the need for processing on a computer or a go between the land and the company's office for processing. It is possible to immediately locate and confirm the losses in the field. The neural axis allows simultaneous analysis of both the frequencies and the level of noise that occurred during the measurements, unique in the sense that no other producer uses this technology and especially beneficial for the correctness of the determinations, the possibility of errors being substantially reduced.

Generally, after the evaluation is completed, measurements will be made with the correlator, both to confirm the results and to determine unequivocally the place of the break . Considering these aspects and the vital importance of water in the evolution of humanity, specialists in the field have tried to apply the latest loss detection technology.

The new Tehnology

Use of SAR sensors on satellites to detect water leakages in pipelines:

Technology developed by UTILIS

Here are the steps involved in a typical missile detection project

Step 1: Obtaining and analyzing images

A typical project will focus on a defined area established by the water company where they know large leakage areas and night lines, or DMA with high percentages of plastic and CA pipes. The satellite will cover the specified area by acquiring raw images using synthetic radar sensors (SAR). These sensors send the electromagnetic waves that collect data from the surface of the Earth to send them back to the satellite.

Step 2: Radiometric corrections and algorithmic analysis

The raw data collected by the SAR sensor must be prepared by filtering unwanted satellite sounds from buildings, other man-made objects, vegetation, lakes, pools, drains and sewage resources and a whole range of other interferences.

Each pixel in the acquired image is passed through a unique algorithm that has been developed to look for the spectral signature of drinking water.

At this stage is added the utility pipe layer, which provides the leaks identified on a map along with the streets and pipeline locations, which display thousands of square kilometers.

Step 3: Leakage Report and Delivering Results

An entire network can be studied periodically, providing more sets of findings annually. Customers will receive data in the key markup language (KML) that can be added to their GIS systems and maps, web or mobile applications to produce a global leakage sheet.

Areas that have a low probability of leakage will be marked in blue, where areas marked with red mean a high probability of leakage. Drain technicians are then sent to areas to find the exact place.

Depending on customer preference, results can be provided in one of four ways:

- Web-based GIS

- Leaksheets for field work

- application that allows remote access;

- GIS files

Step 4: Confirm the results on the ground

There may be situations in which leakages have been reported or repaired after taking over the satellite image and their confirmation is done before the on-site check-up begins.

Case Study - Pitesti Summer School 2018

Starting from this aspect and encouraged by the results obtained by this method to other Romanian counterparts (RAJA Constanta, Apa Nova Bucharest, Aquaserv Targu Mures etc), the loss detecting department together with SC APA CANAL 2000 SA decided to use this method and in its coverage area. We contacted the Romanian partners of UTILIS and SC BioTech SRL for setting the details and establishing the steps to follow. After that, the scanning area was established, the coordinates sent to the service provider, UTILIS, which performed the scanning of the required area, made the radiometric corrections and determined the possible leakage of water. Utilis has submitted the results both printed and electronically to the operator, and so at the end of June together with SC BioTech SRL we decided to organize a practical workshop in Pitesti to detect water leaks based on the results of UTILIS. In this respect, in collaboration with the Romanian-German Aquademica Foundation and SC BioTech SRL and UTILIS, it was established that on July 9-11 we will organize a meeting with the detection teams in the country and in the form of a contest and try to locate as much as possible many damages. Ten teams representing the water companies in Timis, Dolj, Prahova, Neamt, Maramures, Buzau, Covasna, Targoviste, Turda and Brasov to identify as many water losses as possible in the Pitesti municipality.

As a result of the water network scanning there were identified 83 areas with possible damage in Pitesti, which had to be localized by the participating teams by classical (acoustic) methods. From these areas, 5 areas / team were selected and teams could use any method to locate as many as possible damage. Each team was able to enter the UTILIS application where they could identify the area and contributed where the investigations had to be made. The team that located the first crash was the team in Buzau (about 20 minutes), the team that was awarded by BioTech. The weather was more of autumn than summer, the rain came and did not want to leave. However, all teams have shown involvement in locating water loss.

Weather conditions were tricky, plus traffic, environmental noise and other unexpected traps. Under the aforementioned conditions, 23 locations were identified with the damages, the damages to be dug up and repaired. There are dangers that have consistent flow rates (5 l / sec) and which have not been reported by anybody collect in time considerable amounts of water lost in the sewage system.

The mission of the detectors was to go ... on the tracks of the satellites and narrow down the "suspect" area of defect, so that the maintenance teams could take over the part of the excavation, replacement and restoration, that is, the repair of the defect.

The team that first localized network failures was Buzau, in a record time of 20 minutes, the detectors being awarded by BioTech.

About the technology used to detect the loss of water in space, we spoke in advance of the practical test. Biotech presented the results to the participants, and the representative of the water company in Craiova, who carried out the network scan, shared the experience. Loss experts have agreed that the "satellites" method does not solve all the losses on the ground, but it helps field people with clues about where to look for defects.

As with any competition we have a winner. The winners of this edition are colleagues from Piatra Neamt: Alexandru Postăvaru and Costel Spiru.

Using GPR in rapidly locating networks and water losses

Ground Penetrating Radar (GPR) is used to detect subsurface features and objects.

The machine rests on collapsible and highly portable three-wheel cart that is pushed over the surface. A radar signal from an antenna passes into the ground and reflects off objects under the ground. The information is displayed on a screen providing real-time views. Mapping subsurface utilities: GPR, sondes, cable/pipe locator and CCTV is used to create a “map” of underground services. One instrument on its own cannot provide the accuracy needed for such a survey.

Possibilities with GPR

Environmental Impact Assessments: locate sub-surface objects, water table mapping
2D & 3D imaging
Locate pipelines, cables, ground disturbance, tanks & voids

GPR scan image

Using the permanent logger chairs for the water flow rate .

The PermaNET+ system from HWM combines Permalog leak noise sensor and our versatile telemetry data technology to create a fixed network to monitor leakage. Once installed, leak data calculated using the proven Permalog algorithm, and secondary data, is transmitted via low cost GPRS or SMS telemetry. This removes the requirement for expensive site visits and “drive by” data retrieval.

PermaNET+ allows leakage teams to monitor the status of each logger deployed from map based host software. This can be viewed from any internet enabled device using PermaNETWeb. The system works in conjunction with Google Maps technology to provide a live on screen tracking, allowing leakage teams to respond quickly to problem areas and bring them under control efficiently.

Once the presence of a leak has been identified, secondary measures can be used to check and remove ‘false positives’ and also to localise the leak position.

Correlation – Audio files are used tocorrelate remotely to localise the leak position for follow up

Aqualog – Remotely retrieving the Aqualog detailed noise graphic, clearly indicates the consistent presence of a leak.

Audio – For operators who prefer to ‘hear’ their leaks audio files are transferred to the host.

PERMANET WEB

PermaNET Web is a secure, web based portal designed to enable the remote identification of network leakage.

Supporting accoustic correlation, leak detection and logger location, PermaNET Web can be used with multiple loggers and provides the user with numerous ways to view selected data.

KEY FEATURES AND BENEFITS

Two-way communication: local and remote logger parameter settings

Auto processing: interference and external noise filtering

Time synchronisation: automated synchronisation from remote data server and network

Data Security: firewall - locked down to used ports only. Users have separate logins and locational access. Regular updates and penetration testing

Compatible: supported by all major web browsers

Noise Filtering: auto-processing for equalisaiton, frequency correlation and coherance

Cost and Time Efficient: remote leak noise listening

Alarm Profiles: alarm available via e-mail

Audio Data Recording: audio data is sent to the server if a leak is present

Thermal Camera

The presence of leaks in hot water systems is often first indicated by low boiler pressure or a constant need to top up the boiler, meaning that there is very little clue as to the location of a leak before investigations begin. Identifying hot water pipes throughout a property and finding water leaks can be a time-consuming and labour intensive process when the system is hidden under tiled or concrete flooring. Conventional inspections lead to digging up floors which in turn results in great expenditure in terms of both materials and labour as flooring is lifted and restored. Thermal imaging provides a cost-effective, time-saving solution to these problems.

Choosing Your Thermal Camera:

With temperatures typically falling between 15˚C to 30˚C, leak location applications generally do not require extremely advanced or expensive thermal imaging equipment. We advise considering cameras with a resolution of no less than 120 x 90 pixels but ideally 160 x 120 and a thermal sensitivity of between 0.1˚C (100mK) and 0.06˚C (60mK). An easy-to-operate “point and shoot” camera such as the FLIR E5, FLIR E6 or Testo 868 would usually be suitable although more challenging leaks may require a more advanced camera. Information on our cameras for purchase can be found on the Thermal Imaging Camera page whilst a separate page provides information on Thermal Imaging Camera Hirewhich often proves a great option for one-off or occasional use.

How It Works:

Whilst floors typically remain at room temperature (18˚C to 21˚C), hot water pipes tend to raise the surface temperature of the floor by approximately 4-5˚C when in operation so it is important to turn the boiler on before carrying out an inspection. A thermal imaging camera will depict heat patterns with a colour contrast which clearly shows the pipes under the floor. The majority of our cameras have an autoranging function that can seamlessly adapt to the temperature differentials detected and display these clearly on screen for quick and simple scanning. Figure 1 is a typical thermograph showing hot pipework in a bathroom.

Figure 1: hot pipework in a bathroom

How to Locate the Leak:

Water leaking from hot water pipes will produce a distinctive thermal pattern on the surface of flooring. Whereas pipework produces a relatively sharp picture with clear differentiations between the hot pipes and cold surroundings, leaks appear as more of a splodge on the camera screen with a bright hot-spot centre and gradual gradient to the cold floor. Figure 2 shows a leak under tiled flooring.

Figure 2: leak under tiled flooring

Where water leaks are hidden below multiple layers of flooring, a more powerful thermal imaging camera may be required. A higher 320 x 240 pixel resolution, such as the FLIR E8 or E75 will often be capable of showing heat patterns from pipework below carpet, rubberised underlay and up to 90mm into concrete screed. Leaks can be marked with tape for later inspection so that the thermal inspection can be carried out in one session over the whole property. This allows multiple leaks to be located before digging up flooring in order to rectify issues.

The benefits of using thermal imaging to trace concealed pipes and find hidden water leaks are very clear. By depicting the heat patterns of a hot water system, the user can accurately target physical intervention so that fixing leaks causes as little disruption and damage as possible.

Conclusion

Finally, if we analyze, each method has its advantages and disadvantages. For a complete success in eliminating water loss, it is a good idea to combine the classic detection methods with the modern ones, depending on the specific situations of the individual networks. Combining these methods can lead to very good results. Using these combined methods we succeeded in SC APA CANAL 2000 SA Pitesti between 2016 and 2018 to reduce the distribution losses in the network by about 16 %.