Understanding submergence is one of the most important aspects of proper flume operation. Virtually every type of flume available is vulnerable to submergence to some degree, and if you’re not able to detect and correct this issue, it can be difficult to take the accurate readings that you need for continued operational success.
Before you install a flume in your system, it’s a good idea to learn a little more about submergence, including how you can visually detect it. Here are a few things that you need to know about submerged flumes if you want to maintain the long-term success of your flow management operation.
What Is Submergence?
One of the most commonly misunderstood facts about submergence is that the flume must be completely underwater for submerged conditions to exist. While this certainly can occur, submergence can be present even if most of the flow device is still visible.
Basically, submergence means that flow is not able to freely make its way through the flume. If the downstream channel prevents flow through the flume by as little as 1 percent, then submerged conditions can exist. Generally, the most effective method for detecting submergence is performing a flow calculation. Fortunately, you can also detect submergence visually in some circumstances, which is generally much easier.
Visually Detecting Flow
If your operators aren’t familiar with the submergence equations, then they can detect submerged flumes with a basic visual inspection. Although this may not be as accurate, it is a very simple way to determine if submergence has occurred.
If your flow has not fully transitioned from free flow to submergence, visual detection will be much more difficult. After this transition has completed, however, there are a few signs your operator should look for. In a flume where free flow exists, you should notice a wave with a slight froth just past the throat section of your flume. If you see this wave in the throat instead of past it, or if there is no froth, then you’re seeing submergence.
What to Do About Submergence?
The problem with submergence is that it can make it more difficult for your operators to take flow readings. That said, your flume will still function while experiencing submergence. If you prefer free-flow conditions, however, there are a few things that you can try.
The most effective solution is installing a flume such as an H-flume that’s resistant to submergence. If you already have a flume, you can prevent submergence by making sure that there is a drop in elevation in the throat section. You can also perform regular maintenance on the downstream channel to make sure there isn’t anything that could interfere with free flow.
Find a Flume
Now that you know how to detect submerged flumes, you should be able to deal with this common flow issue. If you’d like to purchase a flume that’s resistant to submergence, start shopping with Tracom, FRP.
We provide a wide range of first-rate fiberglass flumes, including H-flumes that prevent submergence in most circumstances. Contact us today for information about our flumes or to request a quote for one of our products.