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The H Flume was developed to measure runoff in small experimental plots and agricultural watersheds. Like a weir, the H flume develops a backwater effect at higher flow rates. In low gradient applications, this backwater effect can cause flooding.

H flumes are commonly used in catchment, runoff, and edge-of-field studies. For a variety of reasons it is not always feasible to provide a full-length approach section at the inlet of an H flume. When shortening the approach section of a H flume, there is always the concern of…

H Flumes have proven to be well suited to measuring watershed runoff from agricultural plots and pastures. In the collage below, the USDA Agricultural Research Service – J. Phil Campbell Sr. Natural Resources Conservation Center (JPCNSRCC) in Watkinsville, GA details the…

Over the years 22 standard sizes of Parshall flume have been developed. Sized by throat width, these standard flumes range from 1-inch all the way up to 50-feet. With so many sizes available you would think that there wouldn’t be a call (or need) for intermediate sizes.…

Salt and pepper. Peanut butter and jelly. Trapezoidal flumes and flow measurement in ditches. What do they have in common? They each go great together! Originally developed to measure flow in irrigation channels, the Trapezoidal flume has become the flume of choice when measuring…

A common problem we encounter in talking to customers about using weirs is lack of understanding of where the correct point of measurement is. Unlike a flume, where the point of measurement is in the body of the flume itself, for a weir, the point of measurement is upstream of…

Monitoring surface waters presents a unique set of problems not encountered when measuring sanitary or industrial discharges. Chief among these is vegetative matter and the need for flume maintenance. Even flumes that pass solids and debris well can experience flow channelization…

In selecting a material of construction for a flume or a weir, it is not uncommon for the decision to be made “go with stainless” without a consideration of the grade of stainless that best fits the application.

Stainless steel flumes offer the ultimate in abrasion and chemical resistance when measuring open channel flows. While other materials of construction can provide some of these benefits, they either do so only partially (e.g. PVC for chemical resistance but not abrasion) or at…

Fiberglass packaged metering manholes are an innovative solution to the problem of needing to measure piped flow below grade. Packaged metering manholes factory integrate a flow element (usually a flume, but weirs and magnetic flow meters can also be integrated) directly into a…

The wide flow ranges of H flumes make them ideal candidates for measuring edge-of-field or catchment flows. Likewise, Parshall flumes work well when measuring creeks, streams, rivers, and other watershed contributors. However, when flumes are used to measure flow in channels,…

Fiberglass Parshall Flumes are the standard for measuring influent and effluent flows at wastewater treatment plants (WWTPs) in North America. Widely used in surface water / irrigation applications, the Parshall flume adapts well to sanitary applications while fiberglass resists…

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 traditional method of connecting Parshall flumes to piping has been through the use of end adapters. On the inlet side, the purpose of an end adapter is to expand the flow from the pipe into a channel wider than the entrance of the flume and then contract flow in a controlled…

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.

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.

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.

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 initial…

Being a contractor isn’t easy. There are weather delays, subcontractors to schedule, equipment to install, progress charts to update, client meetings, and permits to obtain. The list goes on and on. You can't be an expert in everything and even many consultants don’t design…

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.