Blogs

Foam in flumes or weirs is a headache. It's a source of measurement error, and it frequently requires additional maintenance and monitoring. This article is not intended to discuss the causes of foam (other than an overview); instead is intended to provide practical solutions…

While we frequently talk of the advantages that flumes have over weirs, weirs in general (and weir boxes in particular) can be well suited to measuring flows on unusual pipe configurations. Without considerable flow conditioning, flumes require the approaching flow to be centered…

Over time a primary device’s (flume or weir) staff gauge may need to be replaced. Wear, vandalism, nature of the flow stream, and device construction can all play parts in a gauge needing to be replaced. When replacing a gauge there are two styles available: adhesive gauges and…

A Weir Box is simply a fabricated box or vault which incorporates a weir plate to measure the flow of piped water. Weir boxes work best when measuring flows from about 10 gpm to 500 gpm. Lower than that and accuracy falls off rapidly. Higher than that and the weir box becomes…

For a weir box to provide accurate flow measurement, the flow approaching the weir needs to be well distributed as it enters the weir pool. Unfortunately, weir boxes are usually used to measure flows in gravity pipe systems. The answer is upstream baffles. Properly configured,…

A defining characteristic of a weir is its need for the approaching flow to be sub-critical (Fr 1) by means of the weir notch and spilling discharge. The acceleration of flow from the sub-critical to the super-critical allows for the establishment of the level-to-flow…

End-of-pipe applications always present a problem when it comes to measuring the flow. One good idea that we’ve run across is using a precast trough with a weir plate. The trough is butted up against the end of the pipe to direct all the flow through the weir.

A key parameter in measuring water quality is Dissolved Oxygen (DO). DO is often used as a quality of water indicator for water used by people or which serves as a habitat for aquatic flora and fauna. While it has been known that weirs can affect DO levels, a systematic…

We often talk about how flumes and weirs accelerate sub-critical flow to a supercritical state and how that in turn develops the level-to-flow relationships that are used to determine the flow rate. In the past we’ve defined the various stages of critical flow by the Froude…

After you’ve selected whether flume or weir for your application, you then have to think about which type of flow meter to use. Usually this comes to down to using an ultrasonic or a bubbler flow meter. Price is a strong advantage for ultrasonic meters – in many ways…