Pressure loggers provide data and visibility on how the network
is performing. They are normally installed at strategic points in
the network, such as at Pressure Reducing Valves (PRV), the
Average Zonal Pressure (AZP), or the Critical Pressure Point
(CPP). Traditionally, pressure loggers stored data until physically
read in the field during scheduled visits, often collecting weeks
of data. Many loggers can now upload data directly to online
servers or SCADA systems via GPRS/GSM or Radio, making live data available. Loggers are designed to be extremely robust, waterproof units, withstanding tough conditions underground for as long as 5 years without maintenance.
There are a variety of pressure loggers that can log many different variables depending on their location and requirements. The simplest loggers record one channel of pressure data and are suitable for locations such as the AZP or CPP. At PRVs, loggers can record multiple pressure channels. Advanced loggers can also record information on temperature, GSM signal strength, and battery voltage. Other channels may also be logged relating to control systems on a PRV.
Loggers generally provide logged data at 15 minute intervals. Faster logging can be used to provide greater visibility. Five minute logging is becoming more prevalent. Short periods of very fast logging (typical 1-100Hz) can be used to detect high-speed events like pressure transients and surges in the network. A trigger event is programmed to initiate the high speed data capture, or a rotating buffer is used that is constantly stores and flushes data, with the event trigger stopping the over-writing of critical data.
Some “smart” loggers are capable of two-way communication and can receive new configurations as well as send data. This can be used to remotely tune the loggers to change reporting rates, trigger events, data acquisition rates or logging frequency.
Loggers form the foundation of any good network monitoring system. They provide the data and visibility to allow engineers to make informed decisions on the setting and management of their network. Without consistent, accurate and reliable data, it is difficult to manage and adjust network conditions over time. Pressure loggers enable the intelligent targeting and setting of pressure management (e.g. PRV settings and pressure control) over time.
To make the most of loggers and enable the intelligent targeting and setting of pressure management, water utilities need to:
Identify key locations in the network to log the data (e.g. PRV, AZP, CPP)
Install a suitable amount of loggers with acceptable levels of accuracy, communication and cost
Ensure that data is transmitted regularly, typically one a day or more
Ensure that the data is stored and more importantly made accessible to help in the understanding of the water network