Measuring open-channel flow
As water flows over the dam, can we measure it?
Dear Control Engineering: Do you have any information about measuring flow in an open channel? This is to measure flow over a dam. Are there companies that make such devices?
Regards, Bhumika Yagnik
Measuring flow through an open stream is probably among the oldest instrumentation applications you can imagine. One of the simplest approaches is to cut a notch in the dam, either a square cut or a V shape, and calculate your flow based on the height of the water (or whatever liquid it is) flowing through the cut. Using a V gives you a greater turndown ratio. This is called a weir, and there are formulas that allow you to make a pretty good approximation of the volumetric flow.
There is a second method called a flume where you measure the liquid flowing through a known geometry. The most common is probably a Parshall Flume (named after Ralph L. Parshall) that uses a combination of horizontal and vertical geometry. There is at least one company, Tracom Fiberglass, that makes fiberglass shapes to help you construct this configuration in your stream. This may require pouring come concrete depending on the volume you have in mind.
If you want something a bit more sophisticated, some ultrasonic flowmeters can be used to measure open streams. Alpha Controls and RS Hydro are companies that offer a selection of such units. Good luck with your efforts.
Peter Welander, email@example.com
- Events & Awards
- Magazine Archives
- Oil & Gas Engineering
- Salary Survey
- Digital Reports
Annual Salary Survey
After almost a decade of uncertainty, the confidence of plant floor managers is soaring. Even with a number of challenges and while implementing new technologies, there is a renewed sense of optimism among plant managers about their business and their future.
The respondents to the 2014 Plant Engineering Salary Survey come from throughout the U.S. and serve a variety of industries, but they are uniform in their optimism about manufacturing. This year’s survey found 79% consider manufacturing a secure career. That’s up from 75% in 2013 and significantly higher than the 63% figure when Plant Engineering first started asking that question a decade ago.