What You Should Know About Weir Boxes

If you’re looking to measure the flow of piped water, there’s no solution quite like a weir box. These handy devices are used to provide accurate measurements you can count on, provided you’re dealing with a flow somewhere between 10 and 500 gallons per minute. Before you get a weir box of your own, there are a few factors to keep in mind. Here’s everything you need to know about weir boxes.

When You Need a Weir Box

Not all flow channels provide the best conditions for a weir box, but there are a few instances where a weir is clearly the best option. One of the most common scenarios is a flow with solids that need to be captured, like dam seepage collection. A weir box would be able to secure the solids effectively. In other cases, a weir box is a functional alternative to a flume when the upstream conditions prevent a flume from providing accurate flow rate measurements. 

Plate Types

The weir plate is the most important aspect of a weir box, and there are several different types to consider before choosing one that’s best for your flow channel. You can utilize a V-notch or Cipoletti weir, which are the most common, or you can opt for rectangular weir plates if your box’s width is appropriate for that kind of feature. 

How Weir Boxes Measure Flow Rate

Measuring flow rate is the primary purpose of a weir, so it’s important to know exactly how it gets the job done. While weirs work similarly to flumes, they don’t measure flow rate at the same point, as the point of measurement is upstream of the actual plate. Additionally, the floor of the weir box and the zero elevation are different. Remember, the zero elevation is the point from which the water level is measured, so it needs to be clearly marked or recorded somewhere.

Weir Box Materials

Like flumes, weir boxes can be made from a variety of different materials. Among the most common are aluminum and stainless steel, thanks to their resistance to corrosion. Galvanized steel is another option if you’re looking to save as much as you can on your weir box. If you want lightweight corrosion resistance that’s also customizable, however, fiberglass construction is your best bet. Fiberglass allows for a wide variety of shapes and sizes to be crafted as a single structure no matter how odd the design may be.

Weir Boxes From Tracom

If you’re looking to get highly accurate measurements in a low flow system, our weir boxes can get the job done easily. With everything you need to know about weir boxes in mind, you can find the right setup for your unique flow channel and get yourself a durable weir box constructed from quality fiberglass materials. Each of our weir boxes comes complete with a fixed weir plate and inlet baffle, so all that’s left is installation. Contact us today to start the process of getting your own weir box!