Water Engineering Laboratory Research Articles

Performance Assessment of Pneumatic-Driven Automatic Valves to Improve Pipeline Fault Detection Procedure by Fast Transient Tests.

The use of fast transients for fault detection in long transmission networks makes the generation of controlled transients crucial. In order to maximise the information that can be extracted from the measured pressure time history (pressure signal), the transients must meet certain requirements. In particular, the manoeuvre that generates the transient must be fast and repeatable, and must produce a pressure wave that is as sharp as possible, without spurious pressure oscillations. This implies the use of small-diameter valves and often pneumatically operated automatic valves. In the present work, experimental transient tests are carried out at the Water Engineering Laboratory (WEL) of the University of Perugia using a butterfly valve and a ball pneumatic-driven valve to generate pressure waves in a pressurised copper pipe. A camera is used to monitor the valve displacement, while the pressure is measured by a pressure transducer close to the downstream end of the pipe where the pneumatic valve is installed. The experimental data are analysed to characterise the valve performance and to compare the two geometries in terms of valve closing dynamics, the sharpness of the generated pressure wave and the stability of the pressure time history. The present work demonstrates how the proposed approach can be very effective in easily characterising the transient dynamics.

A Laboratory Investigation on the Effects of Intermittent Water Supply and Remedial Measures

AbstractThe intermittent water supply (IWS) of water distribution systems is a common practice caused by the imbalance between available water resources and customers' demands. Transition to the continuous water supply (CWS) is desirable to reduce quality, equity distribution, and pipe integrity issues but is often practically unachievable in the short or medium term. The World Bank funded a laboratory activity at the Water Engineering laboratory of the University of Perugia, Italy, to investigate how remedies can be introduced to mitigate the impacts of IWS and preserve pipe integrity, facilitating the transition from IWS to CWS. The results of the tests with different feeding conditions, downstream outflows, and air valve dimensions and locations are described and discussed in this paper, culminating in typical interventions that can be implemented to reduce, if not completely eliminate, the undesirable consequences.

Transient Test-Based Techniques for Checking the Sealing of In-Line Shut-Off Valves and Capturing the Effect of Series Junctions—Field Tests in a Real Pipe System

In-line valves are devices typically used for isolation or flow regulation in pipe systems, playing a key role in the operational management of transmission mains (TM). However, there is no fast and expeditious procedure available for checking the efficacy of the sealing mechanism, and its ability to prevent leakage, unwanted flow or partial blockages, which is a crucial action for any maintenance operation. Due to the different values of the conveyed discharge, the diameter changes along the TM at a series junctions which therefore makes diameter changes a very common singularity. This paper has two aims. The first one is to evaluate the feasibility of Inverse Transient Analysis (ITA) for checking the sealing of in-line valves. In particular, the primary objective of the numerical model is to identify the distinctive features of the measured pressure signals that correspond to the status of an in-line valve, discerning whether it is fully sealed or partially closed. The second objective is to use Direct Analysis (DA) of the pressure signals to appropriately capture the transient response of the series junctions. To address these issues, safe transients have been generated in a real TM by means of a Portable Pressure Wave Maker (PPWM) device, refined at the Water Engineering Laboratory (WEL) of the University of Perugia, Italy. The results of the field tests and numerical model point out that the positive pressure wave reflected by the in-line valve is smaller than the one expected if it were perfectly sealed. Moreover, the transient response of the series junction has been properly captured by the DA of the pressure signal. Accordingly, the proposed procedures have been demonstrated to be suitable tools for the management of long transmission pipelines.

A Comparison of Psychomotor Domain Assessment in Water Engineering Laboratory between F2F and ODL

Pandemic has changed teaching, learning and assessment (TLA) methods in conducting remote learning during open distance learning (ODL). This scenario has switched physical learning to virtual learning worldwide including UiTM. Ideally it has a positive impact in the academic landscape, however there are challenges for technical programmes which assess psychomotor domain including Diploma in Civil Engineering at UiTM Pasir Gudang. This paper is a preliminary study to compare the student performance before pandemic (Sept 2019-Jan 2020) and during pandemic (Sept 2020- Jan 2021) in addressing psychomotor domain for laboratory courses (water engineering laboratory). Result shows a positive impact on student performance during ODL. However, there is a flaw and weakness in assessing psychomotor domain during ODL. Hence monitoring on TLA should be done for the betterment of TLA for future and continual quality improvement (CQI) is necessary to ensure the quality of teaching for laboratory courses.

Consumption Change‐Induced Transients in a Water Distribution Network: Laboratory Tests in a Looped System

AbstractAt the Water Engineering Laboratory of the University of Perugia, Italy, a wide experimental program has been carried out in a polymeric pipe network with two 100 × 100 m square loops. The aim of this program is to analyze the dynamic response of the system to transients caused by a change in water consumption. To emphasize such a response, transients are generated by the complete and fast closure of an end‐user, located at the downstream end of a service line. During tests, the combined effect of simultaneous consumers, whose consumption is varied both deterministically and stochastically, has been analyzed. The tests allow examining the propagation of the generated pressure waves within the network for different water consumption variations and end‐user locations. The lessons learnt from the experimental results may help the water utility managers to identify the reasons for the higher frequency of occurrence and severity of faults in some specific portions of water distribution networks apparently “similar” to others where damages are less frequent and severe.

Study Of Electrical and Lighting Installations in Water Engineering Laboratory Buildings (Case Study: Laboratory of Water Engineering, University of Muhammadiyah Jember)

Electrical installation of buildings is an assembly of electrical equipment in buildings that are related to each other, to meet certain goals or purposes and have coordinated characteristics [2]. The design and installation of this electrical installation covers all aspects of the building, one of which is for the Water Engineering laboratory building. Electrical power in this laboratory building is used for room lighting, pumps, heating, cooling and so on. Based on the above, to obtain a water engineering laboratory building with optimal lighting, the use of durable pumps, the use of environmentally friendly cooling and heating devices and the selection of efficient and efficient tools for related purposes as well as the use of electricity that is efficient and safe. So it is necessary to study the Electrical and Lighting Installation in the Water Engineering Laboratory Building. From the results of this study, it can be concluded that for this laboratory lighting is used 20 TL lamps with each lamp 18 watts and uses lamps of 1350 lumens, laboratory operations use 2 pumps each with a power of 450 watts and heating and cooling equipment and tools the other has a power of 600 and for the distribution of electricity, 2 MCB panels are used, each of which is 6 amperes. It is recommended that each pump be made an individual panel so that safety in the experiment is not compromised when used together and there is a need for routine maintenance and control.

A Laboratory Set-Up for the Analysis of Intermittent Water Supply: First Results

The evaluation of the impact of intermittent water supply on water distribution systems is a complex task. Laboratory tests, in controlled conditions with virtually no constraints on instrument and device location, allow the analysis of the effects of single parameters on pressures and flows. Within the framework of a research consultancy commissioned by the World Bank, the test network at the Water Engineering Laboratory of the University of Perugia, Italy, was modified to analyse pipe filling and emptying phenomena. Herein we describe the characteristics of the set-up, the available instruments and data acquisition system, as well as the installed devices (e.g., air release and in- and off-line ball valves). The set-up was also designed to investigate the effects of the air flow on the overbilling of water meters. The results of a preliminary test allow the typical phases of the phenomenon to be analysed, including the filling of the pipe with water and the discharging of air, the arrival of the water front at the downstream end causing a pressure variation typical of water hammer, and the emptying process and the filling with air. The analysis allows the operational mechanism to be understood and remedial interventions designed and validated.

A Nelder–Mead algorithm-based inverse transient analysis for leak detection and sizing in a single pipe

Abstract In this paper the results of an experimental validation of a technique for leak detection in polymeric pipes based on the inverse transient analysis (ITA) are presented. In the proposed ITA the Nelder–Mead algorithm is used as a calibration tool. Experimental tests have been carried out in an intact and leaky high-density polyethylene (HDPE) single pipe installed at the Water Engineering Laboratory (WEL) of the University of Perugia, Italy. Transients have been generated by the fast and complete closure of a valve placed at the downstream end section of the pipe. In the first phase of the calibration procedure, the proposed algorithm has been used to estimate both the viscoelastic parameters of a generalized Kelvin–Voigt model and the unsteady-state friction coefficient, by minimizing the difference between the numerical and experimental results. In the second phase of the procedure, the calibrated model allowed the evaluation of leak size and location with an acceptable accuracy. Precisely, in terms of leak location the relative error was smaller than 5%.

Effectiveness of Ceramics Water Filter Pots with Addition of Silver Nitrate to Reduce of Escherichia Coli Contents

Efforts to create a filter alternative in an emergency is very necessary in order to meet the drinking water needs. Filter pottery is one alternative screening models are cheap and mobility, so it can be applied, however, the ability of pottery on filtering raw water into drinking water needs to explored.. This study tested the ability to pottery from a mixture of clay and fine rice husk with 0.001 mole added of silver nitrate and 0.0005 mole within the period of use. This study conducted in soil and water engineering laboratory, Universitas Padjadjaran, Environmental Laboratory Institute of Ecology Universitas Padjadjaran and Energy and Mineral Resources Laboratory, West Java Province. This study also conducted pore size analysis using Scanning electron microscope (SEM) in order to know the pore diameter and pore distribution formed from the ceramic pot filter. The faucal-coli analysis is performed as an indicator of filter quality generated from the ceramic pot filter. The results showed that added of silver nitrate to lower the flow rate of 0:35 l/h. The Increasing added of silver nitrate also showed an increase in water resulting residue 0:02. Increasing the number of used periods to decrease of silver nitrate residue 0001. The results show that ceramic pot filter can reduce the number of e-coli with significant amount. The size of the pores of ceramic pots formed shows a diameter smaller than the diameter of e-coli. There are still some cracks in the process of making ceramic pots, thereby reducing the ability of ceramic pot filters to reduce e-coli.

Matched-field processing for leak localization in a viscoelastic pipe: An experimental study

Abstract This paper applies the matched-field processing (MFP) method to leakage localization in a viscoelastic pipe. The viscoelasticity of pipe wall is included in the governing equations of transient wave via the generalized Kelvin-Voigt model and its effect is finally translated into a frequency-dependent wave speed. Then, a leak is localized by MFP via a 1D search of leak location along the pipe, independent of the leak size. Transient experiments with viscoelastic pipe in the Water Engineering Laboratory at University of Perugia and in the Water Resources Research Laboratory at Hong Kong University of Science and Technology are studied. Experimental results demonstrate that the inclusion of pipe wall viscoelasticity and using more frequencies (instead of using only resonant frequencies) improve significantly the leak localization accuracy. It is shown that the MFP leak localization is accurate even for a small leak (the flow ratio of leak and main pipe is approximately 10%) in a noisy environment: among 50 transient experiments, the maximum error of MFP leak localization is only 1.14 m and in the other 49 experiments the error is always lower than 1 m.

Calibration of viscoelastic parameters by means of transients in a branched water pipeline system

In this paper, different arrangements of Kelvin–Voigt elements are implemented in an admittance matrix model to investigate the transient modeling of water distribution systems. The viscoelastic parameters are calibrated by experimental data acquired during a transient in a branched system of three HDPE pipes at the Water Engineering Laboratory of the University of Perugia, Italy. The dependence of the viscoelastic parameters on the branch characteristic time is investigated. Models with a single set of elements for all branches are compared with models with different sets of elements for each branch. When the same number of parameters is used, the former perform better than the latter. No evident correlation is found between the retardation times of the viscoelastic parameters and the branch characteristic times. The use of two measurement sections instead of one does not modify the calibration results significantly.

Hydraulic characterization and transient response of pressure reducing valves: laboratory experiments

Abstract A pressure reducing valve (PRV) regulates the outlet pressure regardless of the fluctuating flow and varying inlet pressure, thereby reducing leakage and mitigating the stress on the downstream water distribution network (WDN). Notwithstanding the crucial importance of PRVs, few experimental data are available in the literature. The aim of this paper is to overcome this gap by means of the results of a large number of tests carried out at the Water Engineering Laboratory of the University of Perugia, Italy. These tests have been executed on a standard type of PRV in steady-state conditions, to characterize it, and in unsteady-state conditions, to check its transient response. A broad range of laboratory conditions simulating possible events in WDNs has been examined and both short and long duration monitoring have been carried out. The analysis of the tests demonstrates the versatility of PRVs as a powerful tool for pressure management, and also when the flow condition changes according to the users' demand pattern. In fact, their transient response is appropriate with small pressure oscillations generated by the PRV self-adjustment. Moreover, proper PRV modelling has to include both its mechanical behaviour and the characteristics of the pressure pipe system in which it is installed.

Experimental characterization of PVC-O pipes for transient modeling

The increasing use of plastic materials has modified several aspects of design and management of water distribution systems. With reference to the numerical modeling of transients, the definition of a correct rheological model of the pipe material is receiving an increasing interest. In this paper the behavior of the molecularly oriented polyvinyl chloride (PVC-O) pipes during transients is investigated, by means of tests on a PN16 DN110 pipe installed at the Water Engineering Laboratory of the University of Perugia, Italy. Pipe characteristics, such as wave speed and Kelvin–Voigt parameters, are estimated by the comparison of experimental and numerical results. Analyses are performed both in time and frequency domain. The variation in time of the wave speed is investigated. The results show that, while the wave speed value is close to that of other polymeric material pipes, such as Polyethylene, the viscoelastic behavior is less evident for PVC-O pipes. This feature is of particular interest for research purposes in laboratories and for current use in functioning systems.

Machine learning methods for wastewater hydraulics

Wastewater hydraulics problems are frequently addressed by investigation on physical models. Dimensional analysis is a powerful tool that allows discovering essential information about the investigated phenomenon, but in some cases it is affected by significant limitations. In such cases, many issues can be addressed by means of machine learning algorithms, resulting from the theories on pattern recognition and computational learning. In order to show the potential of such an approach, in this study Regression Tree M5P model, Bagging algorithm and Random Forest algorithm were applied to the solution of some complex problems of wastewater engineering: the prediction of energy loss, the pool depth, the air entrainment in a drop manhole, and the forecasting of the lateral outflow in a low crested side weir. The algorithms were trained and tested on data obtained from experimental tests that were carried out at the Water Engineering Laboratory of the University of Cassino and Southern Lazio. In most of the considered cases, regression trees and ensemble methods were able to provide very accurate predictions.

Aqualibrium Competition: Laboratory Data and EPAnet Simulations

The Aqualibrium competition [1] is a fun way to learn about water supply and distribution. A pipe network has to be built with the aim of equally distributing a given volume of water between three reservoirs. The rules of such a competition prescribe that a looped network has to be built and this makes the problem quite complex because of the well-known non-linearity of the governing equations. EPAnet is a powerful tool to improve and fasten the solution of the problem. At the Water Engineering Laboratory (WEL) of the University of Perugia an Aqualibrium equipment is used within the Civil Engineering courses. EPAnet was used to simulate the behaviour of the Aqualibrium network, but the results showed some discrepancies between laboratory tests and numerical simulations under some flow conditions. These discrepancies, as well as the critical role played by energy dissipation mechanism, are discussed in this paper.

Pressure Reducing Valve Characterization for Pipe System Management

Pressure control strategy through Pressure Reducing Valves (PRVs) has been deeply investigated as management strategy, aimed at water leakage reduction avoiding very expensive pipe replacement programmes. On the contrary, few experimental data are available in literature, particularly in unsteady-state conditions. In this paper, the results of some tests carried out at the Water Engineering Laboratory of the University of Perugia (I) in order to characterize a PRV with two set points for high and low pressures are presented. The PRV is installed in a single high-density polyethylene (HDPE) pipe supplied by a tank in which the pressure is assured by pumps of different characteristics. Two types of tests are considered: steady-state tests, to characterize the PRV, and extended period tests, to check its dynamic behaviour.

Experiments and Numerical Simulations of Dike Erosion due to a Wave Impact

Dike erosion is a crucial issue in coastal and fluvial flood risk management. These defense structures appear vulnerable to extreme hydrological events, whose potential occurrence risk seems to be recently increased due to climate change. Their design and reinforcement is, however, a complex task, and although numerical models are very powerful nowadays, real processes cannot be accurately predicted; therefore, physical models constitute a useful tool to investigate different features under controlled conditions. This paper presents some laboratory experimental results of erosion of a sand dike produced by the impact of a dam break wave. Experiments have been conducted in the Water Engineering Laboratory at the University of Cassino and Southern Lazio, Italy, in a rectangular channel: here, the sudden opening of a gate forming the reservoir generates the wave impacting the dike, made in turn of two different, almost uniform sands. The physical evidence proves that the erosion process is strongly unsteady and significantly different from a gradual overtopping and highlights the importance of apparent cohesion for the fine sand dike. The experimental results have also been compared against the ones obtained through the numerical integration of a two-phase model, which shows the reasonable predictive capability of the temporal free surface and dike profile evolution.

Hydraulic Characterization of PVC-O Pipes by Means of Transient Tests

Abstract Molecularly oriented PVC (known as PVC-O) was developed as an improvement to conventional unplasticized PVC (or PVC-u). For a given nominal pressure, the biaxial orientation of the pipe material allows to double the tensile strength and increase flexibil- ity and resistance to cyclic fatigue, with a reduction in weight. Although the PVC-O pipes are produced and used since late 80s, the behavior of such pipes during transients is not well characterized in literature. In the paper we present the results of transient tests carried out on a PN16 DN110 pipe and generated by maneuvering an automatically controlled butterfly valve. The experimental setup has been installed at the Water Engineering Laboratory of the University of Perugia, Italy. Both time domain and frequency domain analyses are performed. The pressure wave speed is evaluated experimentally by means of pressure measurements. Infor- mation deriving from strain gauges is used to verify and characterize the actual viscoelastic behavior of PVC-O pipes.

Leak Size, Detectability and Test Conditions in Pressurized Pipe Systems

The relationships between leak geometry and detectability are explored with a distinction between steady- and unsteady-state based techniques. Various criteria to evaluate the size and detectability of a leak are first discussed. These criteria can be useful for the benchmarking and the comparison of different techniques. Since the test conditions play a crucial rule in leak detectability, the proposed criteria take this effect into account. Further- more, they show that while in steady-state conditions increases in system pressure enhance leak detectability, in transient state, by contrast, higher pressures tend to decrease detec- tability. This effect is also confirmed by experimental tests carried out at the Water Engineering Laboratory of the University of Perugia.

A Stochastic Tool for Determining the Presence of Partial Blockages in Viscoelastic Pipelines: First Experimental Results

Partial blockages in water pipe networks may contribute to large energy dissipation throughout the system and reduce the service effectiveness for the customers. In this paper, a recently developed stochastic model using transient head measurements for detecting partial blockages in water pipelines is tested with two experimental case studies. The model is a stochastic Successive Linear Estimator (SLE, Yeh et al., 1996) previously used in groundwater hydrology for detecting the heterogeneity pattern of the subsurface. The model provides statistically the best unbiased estimate of diameter distribution due to partial blockages and quantifies the uncertainty associated with these estimates. Tests were carried out at the Water Engineering Laboratory of the University of Perugia (WEL) on two high density polyethylene pipe systems. In the experiments the partial blockages were simulated by placing a smaller diameter pipe of two different lengths between the main pipe. Results show that a first good estimate of the length and the size of the blockage can be obtained by a single short duration transient test executed by maneuvering a ball valve located far away from the blockage position.