From simple listening sticks to advanced biosensors, there is a plethora of pipeline monitoring technology now available to water utilities.
By Brendan Robson
Knowing the status of our water pipelines is essential: measurements and information must be collated, presented and appropriate action taken. This data management is now incorporating ‘smart’ technologies and the quantities may approach the ‘big data’ scale. Keeping informed of developments in these areas is fundamental to allocating resources, whether driven by regulatory requirements or impact on revenue: penalty or profit.
Leak detection is high on the monitoring requirements, as one in five litres, or more, is being lost. This is closely followed by preserving water quality. These are balanced by network performance and maintenance management, with the target of being preventative or even predictive. At the customer end of the network, possible consumption charges and conservation are a growing interest. Developments in monitoring systems and data handling is healthy, but not without potential drawbacks.
Technologies & Developments
Accelerometer-based sensors use acoustic signatures to detect leak-induced sounds or vibrations caused by water escaping from a pressurised pipe. Noise measurement can pinpoint leak locations based on parameters like pipe size, distance and pipe material. However, due to the sound propagation theory, these methods may only be accurate for small diameter water mains.
Hydrophone-based acoustic sensors capture sound waves within the water medium. Their improved sensitivity over accelerometers can aid leak detection in larger pipes. Unfortunately these systems can be expensive and have shorter range between detectors.
Meanwhile, pressure transients can indicate leak signatures using high-rate sampling. However, the point of failure is not as accurately located as acoustic-based systems. Additionally the pressure fluctuations of normal pipework activity or regular draw-offs need to be distinguished from leak events. Processing large data sets now employs modern ‘data analytics’ algorithms.
Vibration measurement is a developing technology for detecting leaks in pipelines, including adopting PCB components normally used in mobile phones.
Flow meter and pressure measurements can build a picture of network performance, even to the point of virtual models and statistical analyses. Mass balancing and Data Validation & Reconciliation (DVR) calculation methods are of growing interest.
Event detection and duration monitoring is used for online recommendations or for historical review to understand unexpected outcomes. Such methods can also be incorporated into asset-management systems to provide warning indicators and risk-based predictions such as Likelihood and Consequence of Failure (LOF & COF).
Water quality sensor arrays employ a number of existing measurement techniques including pH, turbidity and conductivity. Other contaminants can be detected using water properties such as optics.
Finally, there are biosensors which monitor the behaviour of living organisms in the water to assess the toxicity of water samples. These arrays can provide real-time data streams via communication networks, which can now adopt cloud-based information sharing.
Wireless Sensor Networks is a common theme in pipeline monitoring. This includes underground transmission as a research and development topic.Other applied science approaches include thermal and pressure sensors using low-power Force Sensitive Resistors (FSR). These have non-invasive benefits. Elsewhere, clever patent applications appear every year, including ‘neurofuzzy’ decision support with geographical information and radio frequency devices.
More traditional tools include visual inspections, CCTV surveys and wall thickness measurements using remote/near field techniques, broadband electromagnetic surveys, or ultrasonic techniques. These are limited to excavation and probable pipeline shutdown. Listening sticks, manual or electronic, are still employed at the simple end of the spectrum.There remains a healthy interest in research and development projects for pipeline monitoring. Funding bodies, such as the European Commission and World Health Organisation, are careful to support the practical exploitations and benefits, especially for growing economies and developing nations.
Batteries not included?
The total costs need to be appreciated before your return on investment is accurate. Some costs may not be obvious in your pipeline monitoring system.
Furthermore, the power supply for your instrumentation is essential. If onboard batteries are used then check their lifetime. ‘Sleep mode’ may be useful, but energy hungry bi-directional communications will shorten service life. Local solar or wind power is attractive but beware as some devices have encapsulated batteries that are non-replaceable. Low or ultra-low power sensors are improving effectiveness.
Getting your data back to base is a universal requirement for all monitoring systems. Ideally this would integrate, or at least interface) with your existing communication system. Your ‘smart’ device may be able to do local processing and only transmit an intelligent summary. Simple signal strength or electronic interference may be crucial given pipe, meter or instrumentation location.
Uni-directional (upload only) signals may avoid the complexity of bi-directional data streams, although in-situ reconfiguration may be helpful, by adjusting a flowmeter’s calibration parameters, for example. Unfortunately, diagnostic data can overload traditional systems.
Security and integrity of your data is a growing concern in our modern world. The newly opened UK National Cyber Security Centre recognises the worldwide threat to countries’ utility infrastructure. Digital systems demand regular review in order to ensure your data is secure in transmission and storage. The physical robustness of your monitoring hardware may also need assessment to protect against deliberate interference, including vandalism, or avoid accidental events.
A perennial problem is technological redundancy. Is your monitoring system designed to be upgradeable? Is the hardware and software adopting industrial protocols, standards or platforms?
We have seen how ‘smart’ meters for electricity consumers are now being ‘dumbed down’ due to the change of supplier or operating expense. This disappointing downgrading may also transfer to the water industry.
Singapore: A success story
Singapore’s modern water supply network boasts the benefits of smart technology and government investment. Their Smart Water Grid incorporates sensors, meters, digital controls and analytic tools throughout the island, including 300 multi-parameter probes to detect both leaks and water quality issues in real-time.
This extensive project is an example of how administration and business can combine expertise with clear requirements in order to cultivate reliable and sustainable water supply for generations to come.
Awash with potential
Like most fashions, there is a need to see past gimmicks to valuable solutions. The digital revolution has been here for a while (now at Industry 4.0), but there has been slow adoption in the utilities sector, particularly due to ageing assets.
A critical strategy to offset fears and risk is to have research, development, field testing and reporting to be guided, and promoted, by industry bodies. Independent and impartial testing/verification will lead to stable standards and clear quality.
From pipeline to tap, ‘smart’ elements are growing in sophistication from monitoring technologies to flowmeters. The amount of data becoming available may require ‘big data’ style solutions in order to gather, filter, present and understand the real-time efficiency and effectiveness of our businesses.
Sharing industrial knowledge and guiding practical developments in pipeline monitoring is the key to success. Some of the case studies in the oil & gas sector may help to cascade experience.
Brendan Robson is a consultant engineer at NEL, the National Measurement Institute responsible for the management of the UK National Standard for Flow Measurement.
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