TECH-TIP: Distribution System Pressure Monitoring

Pressure Monitoring in Water Distribution Systems
Contributed by Deron Austin - Director, Marketing and Communications for Mueller Company

Pressure is one of the primary optimization parameters for the Partnership for Safe Water’s distribution system optimization program.  Utilities completing the self-assessment process monitor pressure at key locations throughout the distribution system to quantify performance and compare results with the Partnership’s optimization goals for pressure, including minimum daily pressure, maximum daily pressure, and the maximum daily pressure fluctuation range.  The use of pressure sensors is required in order to complete the self-assessment process, although their placement may still be under evaluation.  There are a variety of sensors available commercially for monitoring pressure, with varying data retrieval and communication options.  This informative article describes the importance of pressure monitoring to distribution system optimization and discusses one type of pressure monitoring instrumentation option that enables real-time SCADA communication.

Pressure management in pipe networks is fundamental to providing safe drinking water.  The loss of pressure can potentially allow ground water to contaminate the distribution system.  Fluctuations in pressure can affect the physical integrity of pipes.  Surges in pressure have been known to create additional leaks, main breaks and/or dramatically reduce infrastructure life.  Partnership for Safe Water utilities are encouraged to examine the relationship between pressure and main breaks to identify whether any correlation exists between these parameters.  On the other hand, pressure management can save considerable time and money.  Accurate pressure data allows system operators to reduce leakage volumes, energy costs, system maintenance costs, customer complaints, and water quality problems.  In addition, pressure management helps to:

• Reduce unaccounted for (non-revenue) water (NRW)
• Identify potential infrastructure failures related to pressure fluctuations which can lead to significant repair costs.
• Improve pump management and reduce energy costs
• Improve public health and safety

 

A remote pressure monitoring system is engineered for deployment anywhere in the water distribution system where cell phone service or other communication networks are available.  Pressure sensors, typically installed two (2) per district metering area or pressure zone, optimally at the areas of high and low pressure, transmit readings at user-defined intervals to a secure web server. They can be installed using a service saddle tapped into the distribution main or placed inside a meter vault.  Monitoring systems typically includes a lithium 5-year battery and a cellular service contract.

Current and historical pressure sensor data may be accessed by utilities using a convenient and intuitive map interface.  Once logged into a secure website, the customer can see data from all pressure sensor devices that have been deployed.  To review data associated with a specific pressure sensor, the customer clicks its location on the map.  Other screens on the secure website contain device-specific data for location, alarm settings, logging intervals, and historical pressure readings.  The system transmits data via cellular communication to a smart phone, desktop, or SCADA system, where real-time alerts for high and low pressure conditions are provided by email, text, and web interface.

Data collected from pressure sensors can then be input into the Partnership for Safe Water’s pressure monitoring data collection spreadsheets for additional evaluation and submission to the Partnership as a component of the self-assessment completion report and the program’s annual reporting process.

Components of the remote pressure monitoring system include: (1) an AASHTO H20-rated Remote Telemetry Unit (RTU) that houses the antenna and battery; (2) a composite valve box or meter vault; (3) a cable connecting the RTU to the pressure sensor; (4) a 300psi-rated corporation ball valve; and (5) a bronze service saddle.

For more information about remote pressure monitoring systems, please visit www.intelligentwatertechnology.com.