In the Fisher Valve & Instruments YouTube series on reducing cavitation in your process flows, the 3-minute second video, Cavitation Mitigation Part 2 shows a split line demonstration of cavitation. I highlighted Part 1 in yesterday’s post, Reducing Cavitation in Piping.
Emerson’s Melissa Niesen, shows the difference in flow patterns across a thick plate in the line with a single, through hole versus a second plate in the other line with an array of holes, like those found in Cavitrol III valve trim. The cross-sectional exit areas of the holes in the plates on both lines is the same.
You’ll notice how much louder and lower the noise frequency is flowing through the single-hole plate from the cavitation formed by the pressure drop. In addition to the potential damage this causes in the piping, the line with the multi-hole plate also had higher throughput than the line with the single-hole plate.
Each plate hole creates a small flow stream with a vena contracta pressure higher than that typically present in the flow stream of the line with the single-hole plate.
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