Removing Foam From Flumes and Weirs

When you’re looking to get accurate measurements from flumes and weirs, there’s one annoying substance that can make the process difficult. Foam can compromise your measurements and defeat the entire purpose of flumes and weirs, so it’s important that you know what to do about it. Here’s how to deal with foam in flumes and weirs.

Types of Foam

Before learning how to deal with foam, it’s helpful to understand foam itself. There are two primary types. The first is known as chemical foam. These foams tend to be easily collapsible and white in addition to having a general fluffy appearance. They’re what most people think of when they imagine foam. 

Biological foams are the other type, and they’re a bit more difficult to deal with and look at. They have a sticky and slimy appearance with coloring closer to brown than white. They form due to the buildup of hydrocarbons or fat, oil and grease. Proteins and starches can also create biological foams, so keep that in mind if you’re dealing with wastewater from industrial facilities like bakeries. 

Removing the Foam

One of the more obvious solutions is to remove the foam. Depending on the type of foam you’re dealing with, however, this may not be so easy. Chemical foam is fairly easy to get rid of. All you need are defoaming agents applied to the foam’s source. This will break down and control the foam. To prevent foam from forming again, you can apply anti-foaming agents to the area of flow before the foam is generally formed. 

Biological foams are a bit tougher to deal with. Simple chemical agents won’t do much to remove the foam or stop it from forming. A common way to remove biological foam is to install a stilling well or underflow baffle. A stilling well is designed to modify the flow process to direct the stream to an area where the foam can’t follow, while an underflow baffle is designed to capture the foam from the flow allowing for precise measurement.

Changing the Measurement Device

Foam is really only a problem when it comes to using ultrasonic flow meters. These meters work by sending out sound waves and timing how long it takes for their echo to return. The wave needs to bounce from the surface of the wastewater, not the foam, but there’s no way for it to penetrate the foam. Because it’s bouncing off the foam rather than the water’s surface, measurements will be inaccurate.

If possible, changing the way you measure can eliminate the problem that foam causes. A submerged probe or bubbler, for example, is entirely unaffected by foam. The retrofitting of a new measurement device can be quite the endeavor, however, and the aforementioned devices can still encounter some problems caused by biological growth.

Flume Accessories From Tracom

If you’re looking for stilling wells, probe holders or any other kind of flume and weir accessories, Tracom has got you covered. With our commitment to accurate measurements and customer service, we can help you find the perfect solutions for your unique needs. Contact us today to learn more!