What Flow Meter To Use for Flow With Surface Foam?

In addition to finding the right primary device, choosing a flow meter is crucial if you want to accurately measure flow in your system. Finding the right flow meter, however, can sometimes be difficult, particularly if the flow in your operation possesses certain characteristics.

If there’s foam in your weir or flume, for example, it can cause a wide range of problems, including making it a lot more difficult to take accurate flow measurements. Find out what flow meter you should use to measure foamy flow and learn how to condition the flow in your system to make taking readings easier.

What Flow Meters Not to Use

In most applications, ultrasonic flow meters are the best option for accurately measuring flow accurately. Unfortunately, in flumes where foam is present, you won’t be able to use this generally accurate flow meter.

Ultrasonic flow meters send a pulse of sound towards the surface of the flow and then register how long it takes the echo of the sound to return to the meter. When there’s foam on the surface of the flow, the ultrasonic meter will be measuring the foam instead of the water, which typically result in readings that are a lot higher than they should be.

Flow Meters to Use

If you need to measure foamy flow, there are two different types of flow meters that you can use. The first is what’s known as a bubbler flow meter. A bubbler works by forcing an air bubble through a tube and measuring the flow based on how much force is necessary to move the bubble through the tube.

The other type of flow meter you can use to measure flow with surface foam is called a pressure transducer. Pressure transducers work by measuring how much water is directly above the sensor. Because neither bubbler meters nor pressure transducers take measurements using surface flow, they won’t be affected by foam.

Protecting Flow From Foam

If you want to limit foam in your system so that you can use an ultrasonic flow meter, you can add an underplate baffle to your flume. While an underplate baffle doesn’t actually stop the creation of foam, it will stop the foam from reaching the point of measurement.

Another option for preventing foam from interfering with your readings is installing a stilling well in your flume. A stilling well is a small chamber that isolates a portion of the flow. The small inlet that connects the well to the main flow will likely prevent foam from passing through, and you could also add a de-foaming agent to just the stilling well for extra protection.

Find a Flume for Your Flow Meter

Now that you know how to measure foamy flow, you shouldn’t have to worry about this issue affecting the success of your system. If you need to purchase a primary flow management device, shopping with Tracom, FRP is a great choice.

We offer flumes in several different styles, all of which are constructed using long-lasting fiberglass. Contact a Tracom representative today to ask for a quote and to get help deciding which flow device is right for your system.