Category - Weirs
Using Weir Boxes to Monitor Dam Health
All dams have some amount of seepage as the water impounded by the dam seeks paths of least resistance through the dam and its foundation. While this seepage is natural, it becomes a concern if it carries material from the dam itself with it. It’s important therefore to not…
Controlling Surface Water Turbulence with Wave Suppressors
Turbulence results from relatively small volumes of water spinning in random patterns as the body of water moves downstream. Turbulence can be recognized as boils on the water surface or three-dimensional eddies in the flow stream, which appear and disappear randomly. Because…
The Heady Problem of Foam (in Flumes and Weirs)
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…
Advantages and Disadvantages of Types of Weirs
When selecting among the various types of thin plate weirs there are a number of things to keep in mind: Without additional flow conditioning, weirs can require long upstream weir pools - the greater the weir hear head, the greater the length of the weir pool. Weir pools should…
Helping Universities and Colleges with Flumes and Weirs
Openchannelflow is a frequent supplier to and longtime supporter of research universities and colleges. We regularly assist educational institutions on how best to measure flow within catchments and watershed as well as characterizing and measuring edge-of-field flows, green…
Weir Boxes for Confined Space Installations
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…
Cover Options for Flumes and Weir Boxes
Covers are used over flumes and weir boxes for a number of different reasons: eliminating inflow, aesthetics, operator safety, foam, sensor protection, or containing foaming / splashing flows. To meet these applications, Openchannelflow offers solid and transparent covers in both…
Replacement Staff Gauges
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…
Weir Boxes – Everything from Angle to Zero Elevation
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…
How Can I Slow My Flow Prior to My Flume?
For a flume to operate properly the flow entering it must be:
In below grade applications, one device can help a user do all three: The Energy Absorbing Manhole.
Underflow vs Overflow vs Flow-Through Baffles in Weir Boxes
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,…
The Increasing Effects of Supercritical Velocity on Weirs
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…
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