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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…

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…

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…

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…

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…

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,…

There are six standard angles for V-notch weirs:  22-1/2º, 30º, 45º, 60º, 90º, and 120º, but from time to time this range of sizes is not enough. Sometimes there is a need to correct for a weir plate cut at an incorrect angle.  While other…

Let’s face it – we are all under pressure to save money and accomplish our jobs at a minimum of cost.  In stream gauging, it is tempting to use wood (usually plywood) to make a weir from.  Why not?  The shape of a weir is deceptively simple - just a…

Staff ("head" or "level") gauges provide a quick, visual indication of the level of water in a channel, flume, or weir. Although they should not be solely relied on when more precise level measurement devices are available, staff gauges allow operators to quickly gauge the…

Historically, mines were often abandoned without proper (if any) cleanup.  This lack of remediation and cleanup has meant that as water rises in the mine, pollutants, sediment, and debris can all enter what can become a flow of water out of the mine.   Flow monitoring…