Palmer-Bowlus flumes are among the most popular kinds of flumes used for flow measurement. Flumes are great for open channel flows, and the best-quality options can provide you with accurate measurements for years without issue as long as you perform routine maintenance on them every now and then.
While these flumes can provide accurate measurements, that doesn’t come by default. There are several potential issues you’ll have to look out for to ensure your flume is offering the precise measurements you need. Here are the most common Palmer-Bowlus flume problems that you should watch out for to keep your flume in top condition.
Faulty Approach Conditions
For a flume to operate properly, it has to receive flow at a consistent subcritical velocity. Any other kind of approach condition can lead to upstream depths that are far too low for accurate measurement. This kind of inconsistent critical velocity is primarily caused by roughness upstream. Finding a way to regulate the stream or opting for a different flow channel are some possible solutions to faulty approach conditions.
Even if they have a high solid content, flumes are typically pretty good about measuring flows — especially when compared to weirs — but you can still end up with a nasty buildup of debris in your flume. When this happens, the specifically designed flume shape becomes compromised as the flow has to deal with new obstacles. To maintain accurate measurements, you’ll need to clean the debris out of your flume.
Change in Slope
If the slope of a flume changes, its entire functionality changes as the flow through the flume takes on a different kind of obstacle. Accounting for a changing slope can be as simple as adjusting the zero reference point to the top edge of the throat ramp. Make sure the slope stays consistent and is capable of providing accurate measurements in its selected orientation.
Poor approach conditions can affect the flume’s ability to measure, but energetic flows are particularly problematic. It helps to think of it in terms of its Froude number. If this number is greater than 0.6, it can throw off your measurements quite a bit by creating standing waves in the flume. While it is theoretically possible to account for the water level increase due to a standing wave, there’s no reliably consistent way to do so that’s easier than addressing the energetic flow itself.
Find a Quality Flume
Knowing the common flume problems to look out for puts you in the perfect position to get a flume of your own. When you work with Tracom, our team can help you design a flume perfectly fitted for your unique open channel flow. With our expansive selection of flume options that are fully customizable, you can take your flow measurement to the next level in no time. Contact us today to learn more about how we can set you up with a Palmer-Bowlus flume or any other style of flume that suits your needs.