A Parshall flume is one of the best flow management devices that you could install in your system, but if you want your device to work properly, the flow entering your flume must have certain characteristics. Parshall flumes work by accelerating flow through the flume, and if the flow entering your device is too fast, it can interfere with your readings.
If the velocity of the flow in your channel is too high, you need to find some way to slow it so that your flume will function the way it’s supposed to. Here are a few ways that you can condition flow in your operation so that your Parshall flume isn’t impacted by high velocities.
Use a Nested Flume
Installing a nested flume is one of the most effective ways to condition the flow in your system so that it has the correct approach velocity. This is an especially effective solution if you already have one flume installed in your operation.
Using a nested flume creates a larger upstream pool where the flow will slow down before it reaches the throat section of the interior flume. Once the flow does reach the interior flume, it can then be correctly accelerated to a supercritical state so that your operators can take accurate measurements.
Constrict the Throat
If your flume is installed in a natural channel, reducing the width of the throat can be another way to condition flow. Constricting the flow will reduce its velocity, which will then allow your flume to function the way that it’s designed.
Before you choose a flume with a smaller throat width, you should consider the potential effect on the upstream channel. In some situations, a smaller throat will cause the flow to back up and overflow the channel upstream of the flume. If this is possible in your system, you’ll need to pick another flow conditioning option.
Tools for Flow Conditioning
When the velocity in your system is especially high, you may need to add a flow conditioning device to your Parshall flume. There are several accessories you can install in your flume that will condition your flow so that the approach velocity is ideal.
If you’re using a smaller flume, for example, you can install a perforated baffle plate. The flow must pass through the holes in the perforated plate, reducing its velocity. You also have the option of adding an energy absorber to your system. An energy absorber is basically a plate that’s installed in the upstream channel of your system and blocks the most energetic flow, while allowing the slower flows to pass around and into the flume.
Find Your Parshall Flume
As long as you condition flow so that its velocity isn’t too high, you should easily be able to take accurate readings with your Parshall flume day in and day out. If you’re ready to purchase a Parshall flume for your flow management operation, you can shop with Tracom, FRP.
We are your No. 1 source for fiberglass Parshall flumes and other flow management tools, and we are excited to work with you. Contact us today and get a quote so that you can purchase the quality flume that you need.
