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Case Study
The following case study focuses on the experience of a municipal water system end-user that has employed the new valve as a solution to water surge problems.
Yamanashi Prefecture, located immediately west of Tokyo, includes Mt. Fuji and the Fuji Five Lake region, with more than 75 percent of its area covered in forests. Because of the variety of terrain that resides in the water system footprint, the Prefecture has an array of issues concerning water pressure and flow.
This case looks at delivery of water from the filtration plant to a decompression tank. As can be seen from Figure 3, the filtration plant is located at a significantly higher elevation than the tank. The new valve resides at the end of the pipeline, upstream of the tank.
The Prefecture had been using a traditional butterfly valve in this position. However, it found that the line pressure might become dangerous if the valve was operated. The traditional valve, when operated, exhibited pressure levels of over 131-mH2O when closed at normal speed. The problem is that the highest rating for this pipe was 120-mH2O. If this valve was to continue in use, redesign of the pipeline would have to occur. This was obviously undesirable from a cost and downtime standpoint.
In looking for the most cost effective (yet technically effective) solution, the Prefecture installed the new valve. The unique design changed the profile of surge pressure to just over 100-mH2O, well within the limits of the pipe and at a fraction of the cost of pipe redesign and construction.
Figure 4 shows the traditional butterfly valve and the pressure surge pattern on opening.
Figure 5 shows the new valve and its corresponding surge pattern. Note the significant damping of the surge pattern at approximately 100 to 110 on the time access. In this case, the valve demonstrated both cost effectiveness and a technically innovative solution to pressure surge issues.
Laurel Donoho is a research analyst with Frost & Sullivan, 7550 IH 10 West, Suite 400, San Antonio, TX 78229-5616, 877-463-7678, Fax: 888-690-3329, www.frost.com.
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