Managing the pressure within water distribution networks is essential in delivering efficiency, legal compliance, reducing leakage and to help lower carbon emissions.
All water network operators strive to achieve “Zero Bursts and Zero Leakage”, this can be better achieved with Smart Networks.
PRVs, that is “pressure regulating valves”, can be used in series with a network to control pressure based upon flow rate, however the pressure at the remote “sentinel” positions, critical legs and branches should still be monitored to ensure that these locations are receiving the right pressure 24/7/365, in particular where these legs have a wide level of load variation or include tall buildings. Further pressure monitoring will also warn against faults, sudden bursts and help calibrate network devices such as PRV’s and booster pumps.
Radio Data Networks offer a range of retrofit pressure monitors that can provide virtual real-time network feedback without using the internet or dependence on the cellular networks, that are compatible with both modern and legacy pump or PRV controllers, using for example 4-20mA loops.
Thanks to their ability to be operated from batteries they may be installed both on a temporary or permanent basis, typically housed in a roadside bollard and include adaptive transmission rates to conserve energy.
Smart Pressure Management Helps Save Energy
Simply too much pressure equates to wasted energy in pressurising the network. This is a growing problem especially as many companies are now moving away from using water towers, to save on maintenance and security costs. These are typically being replaced with closed networks with pumps using variable speed drives to provide and maintain the pressure, plus PRV controllers.
Hence lowering pressure helps to improve energy efficiency, improves the life of the pumps too and reduces carbon emissions.
Smart Network Pressure Management reduces leakage
The force exerted on the wall of a pipe is directly related to pressure divided by its surface area. Hence as pressure increases so does the force and risk of creating a burst. The larger the diameter of the pipe the higher the risk becomes, the more the potential damage and number of customers inconvenienced.
If there is an existing leak or leaks, the leakage rate will be proportional to pressure too, hence simply reducing the pressure by say by 20% will reduce the leakage rate by circa 20% too, without having to rip up and replace the main.
Simply, the lower the pressure and the closer the pressure is maintained to the legal minimum optimum delivery pressure the lower the chance of triggering bursts, especially with larger diameter pipes where the forces are much greater.
Poor Pressure Management impacts on water quality & service
Pressure spike or transients can dislodge scale and rust in pipes leading to poor clarity. These can be created by poorly trained operators manually attempting to adjust pressure or oscillating PRV controllers.
One of the major weaknesses of PRV controllers is that they try to predict the sentinel pressure (pressure at the furthest location) based upon flow rate. However, if the load is lumpy, perhaps includes large industrial customers or seasonal variations for example conference centres, that switch on and off demand, optimising a PRV controller can become a life’s work.
Smart Network Real-time adaptive radio telemetry vs cellular data logging
Pressure management is no different to voltage management in power distribution networks. Both require real-time data feedback to the controller, in the case of water the pump’s variable speed drives and/or PRV controllers.
Unlike electricity, the data feedback rate in a water network need not be by the second, as the network has inertial delays due to elasticity and storage analogous to a capacitor in an electrical circuit. What the data needs to be is direct from the measurement point to the controller and adaptive especially in the case of battery powered pressure monitoring systems. Part of the “Smart” is where for example the system sends a regular say 15-minute reading in the depth of night, accelerating to perhaps 1-minute or even 30-seconds when a significant change is detected.
Smart Network autonomy is key too and should underpin any cyber security strategy. This is best achieved by keeping the data path away from any 3rd party network and in particular be dependent on the public internet. We all know painfully even with the most secure security keys in the world the internet is not infallible as it can be blocked, suffer from DOS attacks or be simply down for maintenance.
Also think about future proofing, the author can boast telemetry systems deployed in the early 90’s that are still happily delivering data today but can the same be said about any cellular system due to generation “G” migration? This is a touchy subject at present, with the withdrawal of 3G fully underway to make way for 5G as I write.
Radio telemetry is as viable today in water Smart Networks as it was in the 1990’s for simple pressure management. Compared to cellular, Radio Telemetry offers autonomy, that is the ability to create local systems that are adaptive and able to operate from batteries or solar reducing the cost of installation and carbon footprint. Radio telemetry can also deliver pressure readings directly back into controllers at rates that keep up with pressure variations too, thus conserving energy during quiet periods.
Radio telemetry can also work with older legacy systems, enabling upgrades and retrofits to make them Smart. Delivering for example 4-20mA pressure data that can be interfaced into existing system controllers or PLCs.