How do Ultrasonic Flow Meters Work?

While there are several ways to measure flow rate in a flume, one of the most popular is using an ultrasonic flow meter. These handy devices are able to provide accurate measurements while sitting steadily over the flow, typically on a mount positioning it just above the center of the channel. Knowing exactly how ultrasonic flow meters function is essential to making sure you’re getting the accurate readings you deserve. Learn how ultrasonic flow meters work.

Taking Measurements

Ultrasonic flow meters measure flow rate by, as the name suggests, utilizing sonic waves. They transmit a sound wave straight down into the flow channel that bounces off the floor of the flume and returns to the meter. The time it takes for the sound wave to do this is recorded and used in an equation to determine the flow rate based on a preset distance.

The preset distance has to be specific and properly measured for the ultrasonic flow meter to offer accurate measurements. This distance is typically the zero level, but it can be another level as long as the rest of the equation accounts for that difference. It’s just a matter of some simple math to determine exactly where the flow meter should be mounted based on the discharge equations.

Protecting Ultrasonic Flow Meters

Because ultrasonic flow meters don’t actually touch the water, they won’t be degraded by anything that would normally cause problems with a flume. This includes things like grease, sediment, debris and chemicals. They are vulnerable, however, to a variety of other issues including strong winds, steam and solar heating. The latter is a problem because it overrides the sensor.

Fortunately, there are several ways you can account for these threats when mounting your own flow meter. You can apply sunshades to prevent solar overheating, or you can angle the sensor face to mitigate the damage done from any steam. Dampening factors can also help prevent the expression of anomalies in the output signal.

Taking Accurate Readings

To get the most out of your ultrasonic flow meter, you’ll need to make sure that your measurements are as accurate as possible. This may take quite a bit of work if you don’t have a generally cooperative flow channel. Imagine that the water surface has some minor turbulence, making for no easy place to take reliable readings. You could measure by the sidewall or by the center, and either could be off. That’s why it’s essential that your flow is conditioned properly to ensure that the sonic waves are hitting the right spot on the surface.

Wastewater Flume Accessories From Tracom

Now that you know how ultrasonic flow meters work, it’s time to make sure you’re getting the accurate readings you need. At Tracom, we’re happy to help with all your measurement efforts. We also offer high-end ultrasonic mounting brackets to help properly position ultrasonic flow meter sensors. Contact us today to learn more about everything we have to offer.