Issues in Leak Detection（II）

ASSESSING VALVES

Valve assessment is an essential component of effective distribution system management. Malfunctioning, closed, “frozen” and valves lost in the system make isolating a specific area of distribution for emergency or routine repairs difficult, time consuming and on occasion, impossible.

A water service employee uses the new technology to assess a neighborhood’s condition.Initial distribution system valve assessment followed by annual system-wide valve maintenance enhances a utility operator’s capability to effectively control the flow of water within the distribution system. Assessment and maintenance also prolong the life of valves and ensure that those valves can be located, accessed and operated when needed. Assessment also allows a utility to better plan and schedule system repairs and improvements. Assessing valves and identifying their exact location on a geographic information system can help utilities’ reaction times and limit damage to surrounding infrastructure in the event of a water main break.

Historically, leak noise correlators, while effective on small-diameter metallic mains, have had difficulty doing the jobs for plastic and large-diameter transmission mains. They’ve also been difficult to operate, and training has concentrated more on equipment instruction than learning how to effectively find leaks. Leak detection equipment traditionally provides information only about the current state of the pipe with no information on the overall condition of the infrastructure.

However, advancements in acoustic leak detection and pipe condition assessment methods now help utilities to cost-effectively and efficiently detect leaks in difficult pipe types such as plastic. They also can help prioritize water system repairs and replacement without breaking ground or disrupting service. These new methods rely on measuring how quickly an acoustical signal is transmitted along a section of pipe using vibration sensors and acoustic correlators. The process is completely non-invasive; devices are attached to a section of pipe using standard appurtenances such as valves, hydrants or direct attachments to the pipe’s outer wall.