flumes Archives - C.C. Lynch & Associates, Inc.

Excessive Approach Velocity in Parshall Flume Flow Measurement Applications

Since the 1930s, wastewater professionals have relied on the Parshall flume as the primary device for open channel flow measurement applications. Parshall flumes provide a very repeatable relationship between water level (Ha) and flow rate; but, only so long as the approaching flow conditions are appropriate. For any flume design, the hydraulics must cause a…

“Made for the Shade” Temperature Effects on Ultrasonic Sensors

Ultrasonic flow meters are commonly used to measure flow through a flume or across a weir. Often, the temperature effects on ultrasonic sensors are overlooked in the design and installation process. This type of flow meter utilizes an ultrasonic sensor which is mounted above the flow stream. The sensor transmits a sound wave, or pulse, which is reflected off…

What’s a Packaged Metering Manhole?

The Packaged Metering Manhole was introduced to the wastewater market by Plasti-Fab, Inc. in 1982. In its simplest form it consists of a flume molded into a composite (FRP) manhole. The full range of flumes may be integrally molded into the composite manhole, along with inlet and outlet adapters, pipe stubs, and monitoring accessories for…

Solution for Excessive Approach Velocity In Flumes

Accurate flow rate measurement is highly dependent upon the approaching flow conditions. The approaching flow should be well distributed, laminar, and free of surface waves. To aid in the transition of flow from what is typically a wider approach channel into the flume, the use of curved wingwalls or flared transitions should be used to…

Selecting a Flume For an Existing Pipe or Channel

Open channel flow measurement can be a challenge in applications that require the placement of a flume in an existing pipe or channel. While most everyone is familiar with Parshall Flumes, in many cases, there are other flume options that can provide for equal or better accuracy and are better suited for a particular pipe…

Parshall Flumes – Free vs. Submerged Flow

As often as we use Parshall flumes for open channel flow measurement, it is important to understand “free versus submerged flow” conditions; as it greatly impacts the accuracy of the installation…or the lack thereof. While any primary device could be affected by submerged flow conditions, there isn’t much data to be found on the topic.…

Flow Measurement Solution….The H-Flume

Recently, an industrial plant needed an accurate means to measure flow from a tank. Since most commonly used flow equations for weirs rely on a sharp-crested weir plate, the thick tank sidewall presented an issue. We were uneasy with assumptions, no flow chart, and exactly how to convert level to flow rate. Too, windy conditions…

Flume Selection Guidance

One of the most frequent requests that we get from civil engineers during WWTP design is for flume selection guidance. While there are many complex aspects that need to be considered in flume selection and outfall channel configuration, there are a few basic considerations that can be evaluated to streamline the process.

Various Techniques For Flow Measurement At Wastewater Lagoons

There is a stir in flow measurement into and out of sewer lagoons. More and more, we are asked about influent flow measurement for sewer lagoon(s); as engineers try to get a idea on influent flow characteristics; such as peak, dry vs. wet (I&I) and influent load. Many influent lines can be a challenge; as…