Flumes can be incredibly helpful for measuring flow rate, but there are some potential problems that can come with the installation process. Unless all the necessary steps are taken with close attention to detail, your measurements will be thrown off, rendering the effort pointless. Here are the most common problems with flume installation you should look out for.
Failing to Center the Flume
Several conditions must be present in order for a flume to offer accurate measurements, and one of the most important conditions is the flume being aligned with the centerline of the flow channel. If the flume isn’t centered, you’ll find different head readings on each side of the flume. That kind of inconsistency will lead to flawed measurements. Additionally, you may find that without a centered flume setup, the flow will never actually transition from subcritical to supercritical. With that being the case, there’s no spot to take accurate flow rate measurements.
Too Much Upstream Turbulence
The conditions upstream from the flume are just as important as the alignment of the flume itself. In order for proper measurements to be taken, the incoming flow must be well-developed and uniform. Too much turbulence will lead to the same potential problems caused by a flume being off-center, as you may find different head readings on each side of the flume. Surging, unbalanced and turbulent flows will need to be addressed before the flow actually reaches the flume, so additional accessories may be required for installation. Keep in mind that some flume designs don’t allow for flow conditioners.
The Incoming Flow Is Supercritical
In order for a flume to work properly, its flow needs to be subcritical upon entrance and supercritical as it exits so the point of criticality can be measured. If the flow is already supercritical on approach, the point of criticality will never be reached, and that will render all measuring efforts pointless because any reading will always indicate a lower measurement than what would be present should the criticality be normal. This is because supercriticality doesn’t allow waves to propagate properly, as they’d only be able to travel downstream.
Failure to Maintain Open Channel Conditions
A flume must always maintain open channel conditions in order to provide accurate measurements. That means any pipe system can’t be entirely full, and the flow can’t be pressurized. Flows traveling freely across a surface like you’d find in rivers, streams and irrigation channels are the only ones that will work with a flume. Any pipes used must mimic these conditions in order to work properly. This is because any pressurized flow will automatically be supercritical, which leads to failure for the same reason supercritical flows in open channel conditions do.
Find a Flume With Tracom
If you’re looking to avoid the most common problems with flume installation, Tracom has got you covered. Our expertly designed flumes are customizable and easy to install, ensuring accurate measurements for the foreseeable future. Contact our team to discover which flume type would be best suited for your unique channel conditions.