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Investigations by researchers have shown that in sharp-crested weirs even very slight rounding or dulling of the square upstream edge of the weir crest has a measureable effect on discharge. The effect of weir crest rounding on discharge is most evident on well rounded weirs with…

The traditional method of connecting Parshall flumes to piping has been through the use of end adapters.   Unfortunately, industry-wide the end adapters currently offered by Parshall flume manufacutrers take a number of short cuts in bringing flow into their Parshall flumes.…

To accurate measure flow, thin-plate weirs are intended to operate under free-flow conditions with the nappe freely spilling over the weir’s crest.  However, there may be occasions when a weir becomes submerged – either through changes or mismanagement of the…

For years precast concrete manholes have been the default choice in sanitary and storm water applications.  Over the years, though, packaged fiberglass manholes have begun to displace concrete manholes for a number of reasons. Fiberglass manholes are: Light weight (1/10th…

There is a lot of confusion as to what materials are suitable for making a thin-plate weir from.  Some installations use plywood, some stainless steel, some painted steel, and other fiberglass or aluminum. In making a weir plate the most important consideration is the weir…

Once found only at wastewater treatment plants, fiberglass Parshall flumes have spread to a variety of applications where other materials have traditionally held sway.  The shift from traditional materials like concrete, mild steel, and wood – all used during the…

When evaluating among flume manufacturers and their offering there are a number of things as a contractor that you need to consider. We've broken what you need to look for down into (8) catagories: Cost Construction Expertise Focus Lead-times Submittals Support Warranty

In our series on Selecting a Primary Device we looked at:  Choosing Between a Weir and a Flume and Choosing a Weir or Flume Style.  In this closing article we now look at sizing a weir or flume. The basic consideration in sizing a particular style of weir or flume…

In the first article of this series on Selecting a Primary Device we discussed criteria that can be used to select between a weir and a flume.  Now our attention turns to selecting a particular style of weir or flume. The choice of device style is normally dictated by the…

The selection of a primary device (weir or flume) for a particular open channel flow application typically can be broken down into three decisions: First – should a weir or a flume be used? Second – which style of weir or flume should be used? Third – which size…

One advantage of using the Parshall flume to measure open channel flow is that the layout and dimensions of the flume are standardized.  For the range of sizes normally encountered in the field, the sidewalls heights of Parshall flumes are fixed and are: 24-inches [60.96 cm]…

Researchers (both public and private) use instrumented turf plots in order to better understand the varieties of turf grasses, their ability to capture nutrients (nitrogen and phosphorous), the release rate of those nutrients, and optimal watering cycles.  A key component of…

The Parshall flume is the most common type of flume used for monitoring industrial discharges.  The ubiquity of the Parshall flume means that it is usually well understood by pretreatment inspectors and industrial users alike – not an insignificant consideration…

Time and again, we get questions on pipe slope and straight run requirements from customers looking to connect flumes to piping. The questions that usually come up are: What is the maximum upstream pipe slope I can come into a flume with? How many straight runs of pipe do I need…

Part of applying a flume is the selection of one flume type over another. Here we compare Parshall flumes with Cutthroat flumes in:  Design Accuracy Submergence End connections Sizes to help you to compare between the two flume types.

The H series of flumes have shown themselves to be excellent at monitoring flows in irrigation channels and even industrial discharges.  One of the reasons that H flumes work so well is their ability to pass solids.  Another advantage of H flumes is their ability to…

From time to time we like to bring you unusual or innovate approaches that customers use in the field. Located in Red Feather Lakes, CO (elevation 7,890 ft. [2,405 m]), Shambhala Mountain Center is nestled high in the Colorado Rockies in a serene 600-acre mountain valley…

Periodically we are asked the question:  Can Parshall flumes be made out of concrete?  The answer is:  yes, they can (but they usually aren’t)! The use of concrete in makiing Parshall flumes is limited by a number of factors: Ready availability of fiberglass…

Customer - Portland Water Bureau Portland Water Bureau had been using painted steel weir boxes to monitor its Bull Run Watershed dams.  The longevity of these weir boxes was never very high and several sites have had boxes placed and replaced over the years.  Also,…

Historically, flume manufacturers have been like mattress salesmen – they made it difficult to find the information that you need so that you can compare among offerings. In comparing among flume manufacturers keep these 5 things in mind: Are flumes a main product line for…