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In an earlier article we discussed the use of flat 45ª wing walls to transition flow into Parshall flumes.  The article focused on Blaisdell’s observation that a standing wave and wave trough were generated downstream of the intersection of the inlet 45ª…

Fiberglass Grinder Manholes are a unique solution to the problem of mounting a open channel sewage grinder below grade. The all-fiberglass construction means the unit has high-strength, is watertight, and is corrosion resistant…all at about 1/10th the weight of concrete…

Weirs are best used to measure flows that contain only small amounts of suspended solids.  Unfortunately in surface water applications, the amount of solids present in the flow stream cannot be controlled.  Unlike flumes, which tend to be self-cleaning, weirs require…

While many flumes are grouted into place, a sizable number are also installed in earthen channels (furrows, irrigation ditches, creeks, etc.).  The traditional method of excavating the area, packing the earth, installing the flume, and then backfilling with the excavation…

People make mistakes.... The majority of errors in open channel flow measurement result from designers, installers, or operators - not from the equipment itself.  These errors result from a vareity of sources - from a lack to training to inattention to detail - and are…

For a Parshall flume to function correctly it is important that certain guidelines be followed when selecting a site and installing a flume.  In particular, the upstream conditions are of critical importance.  It is tempting to say that there just isn’t room to…

Water storage with dams began early in human history.  Dams are one of the oldest man-made constructions.  Today, dams are used to store water for a variety of purposes, including:  human consumption, food production, electricity production, industrial use, and…

In applications where organic nutrients are high in the flow stream being monitored, there is always a chance of biological growth on the wetted portion of a flow meter bubbler tube.  The small diameter of the opening of the tube (typically 1/8-inch [0.3175 cm] to 1/4-inch…

Flow measurement in arctic locations can be extremely difficult.  By their very nature, the locations are remote, equipment is limited, flows are highly seasonal, and frost heave is an ever-present concern.  Of these problems, frost heave can be the most difficult to…

We see Parshall flumes at wastewater treatment plants monitoring sanitary flows so often that sometimes we forget the original reason that the Parshall flume was developed – to measure irrigation flows.  With 22 sizes available, Parshall flumes are capable of measuring…

One of the primary advantaged of fiberglass flow metering manholes is the ability to accommodate flumes much larger than will fit inside the manhole. By being able to laminate the flume to the manhole barrel, flumes can readily extend upstream / downstream of the manhole barrel…

In talking with customers about weirs, we run into two common misconceptions.  The first misconception is that weirs can read down to zero – that there is no minimum head.  The second is that weirs are more accurate at these flows than flumes. Unfortunately, both…

One of the most common uses of flumes today is to measure sanitary flows; whether this is at an industrial discharge, mobile home park, resort, or wastewater treatment plant.  Unfortunately, flumes are often selected bsed solely on their ability to handle anticipated flows…

Portable weir plates are a good way to stretch your research dollars.  Instead of the traditional approach of having a weir plate custom fabricated for each installation, Openchannelflow has simplified the process by developing a standard weir carrier with four…

There are two conditions of flow that can occur in a Parshall flume:  free-flow and submerged (drowned) flow. Free Flow Free-flow occurs in a flume when there is insufficient backwater to reduce the discharge through the flume.  The primary advantage of free-flow is…

Flumes installed in earthen channels frequently experience the  problems of upstream flow bypass and downstream scour.  One method of protecting upstream and downstream channels is by attaching watetproof geotextile skirts to the inlet / outlet of the flume to direct…