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End-of-pipe applications always present a problem when it comes to measuring the flow. One good idea that we’ve run across is using a precast trough with a weir plate. The trough is butted up against the end of the pipe to direct all the flow through the weir.

A key parameter in measuring water quality is Dissolved Oxygen (DO). DO is often used as a quality of water indicator for water used by people or which serves as a habitat for aquatic flora and fauna. While it has been known that weirs can affect DO levels, a systematic…

We often talk about how flumes and weirs accelerate sub-critical flow to a supercritical state and how that in turn develops the level-to-flow relationships that are used to determine the flow rate. In the past we’ve defined the various stages of critical flow by the Froude…

After you’ve selected whether flume or weir for your application, you then have to think about which type of flow meter to use. Usually this comes to down to using an ultrasonic or a bubbler flow meter. Price is a strong advantage for ultrasonic meters – in many ways…

Flow Metering Manholes can be grouped into two types: open pipe and closed pipe. Closed pipe flow metering manholes use mag meters, clamp on meters, and insertion meters. Open channel manholes incorporate flumes, weirs, or direct sensing (radar, laser, or area velocity) meters.

In an open channel, freeboard is the head measured from the maximum water level to the uppermost watertight portion of the surrounding channel. Freeboard is an important consideration when evaluating the impact of the installation of a flume or weir. Weirs in particular require…

This overview provides information on the advantages and disadvantages of thin-plate, sharp-crested weirs for measuring the flow of water in open channels. Additional information is also provided on unique features and application notes on various weir types. Source: Teledyne…

When using a weir to measure the flow of water in a natural channel or man-made structure, one of two flow regimes are present: free-flow or submerged flow. Free-flow, also called modular flow, is when the discharge of the weir is not restricted by downstream conditions – where…

At its most basic a weir is nothing more than a structure over which water flows. Their simple design and wide range of styles offer certain particular advantages.

When mounting an ultrasonic sensor over a flume or weir one thing that frequently gets overlooked is the blanking distance - aka deadband - of the sensor. The blanking distance is that distance from the face of the ultrasonic transducer in which the flow meter will blank out (or…

Weir boxes provide the utmost in versatility when it comes to how the flow enters and exist the box. Flow can be piped inline, offset, or even free-spilling into and out of the box. However, sometimes this flexibility can cause problems when it comes to accurate flow measurement.

Flumes and weirs have historically been the tools used to measure the flow of water in natural and manmade channels. Either can be used by itself (with the operator taking manual level readings) or in conjunction with a secondary flow meter for automated data collection.