weir box

Weir Types for Flow Management

It’s no secret that weirs are excellent for measuring flow rates in open channels. They use a thin-plate, sharp crest design that is applicable to a wide variety of flows in terms of velocity and solid content, but there is no universal design to fit all possible scenarios. Because of the different demands of various open channels, you’ll have to find the best fitting weir type.

Just about every weir is accurate, flexible, easy to install and features low construction costs, but you’ll have to focus on more unique features when finding the right weir for your needs. Learn all about the various weir types for flow measurement and discover which design is right for you.


One of the most common types of weirs is the V-Notch. It’s so popular because it works well with low flows, which are common. Flows of less than 1 cubic foot per second are best suited for V-Notch types, but these triangular weirs can also measure flows of up to 10 cubic feet per second. Additionally, the available notch angles range from 20 degrees to 120 degrees, leaving much room for flexibility.


Rectangular weirs can come in two forms. They can either be contracted or suppressed. Contracted weirs are used primarily for higher flows with a complex discharge equation. A suppressed weir is largely the same, but it’s more flexible in terms of installation, as the discharge equation is much simpler. The downside of a suppressed weir is that you have to properly aerate the nappe for accurate measurements.


Most weirs have to account for the changes among a natural open flow channel, but a proportional weir can be used if the channel is man-made. The discharge in a proportional weir is the same as the head, and installation in a man-made channel is among the easiest of them all.


Not every scenario allows for a traditional weir box. Sometimes, a circular weir is the best fit, though this typically only occurs when you need to mount a weir in a pipe. Just keep in mind that the flow rate is a matter of the open weir area rather than the literal pipe size when installed.


Cipolletti-style weirs are among the most uncommon because they provide notably less accurate flow measurements compared to triangular and rectangular options. The primary difference is that the notch ends in a Cipolletti angle out a bit, leading to a simplified discharge equation. 

Finding the Right Weir Types

When you’re looking for the right weir types, there’s no shortage of options to choose from. That’s why you should never go through the process alone. Fortunately, there is a way to get the consultation you need to find a weir box that fits your flow measurement needs perfectly.

With help from Tracom, you can have industry veteran experts at your side helping you customize your weir box to achieve accurate and long-lasting results. We have a large selection of weir boxes on offer for you to peruse, and each one is customizable to your unique needs. Contact us today to learn more about everything Tracom can do for you.