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Submergence in a flume is where the downstream conditions are such that they limit or restrict flow out of the flume. It’s important to check for submergence, as limiting the discharge means that the flume will OVER INDICATE the actual flow rate. To determine if a flume is…

In his original developed of what would become the Parshall flume, Dr. Parshall arbitrarily defined the length of the converging, inlet section of his flume as: For throat widths greater than 8 feet, this relationship was found to be unsatisfactory, and the converging section…

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…

H Flumes can be a good choice when monitoring stormwater flows, whether mounting in a channel or at the end of a discharge pipe. H Flumes provide the low flow sensitivity of a thin-plat weir with the self-cleaning features of a flume. More than any other style of flume, H Flumes…

A hot spring is a natural upwelling of geothermally head groundwater. They can vary widely in temperature from those suitable for bathing to others so hot that immersion results in death or severe injury. Hot springs may contain high level of dissolved minerals (ranging from…

This overview provides information on the advantages and disadvantages of flumes for measuring the flow of water in open channels. Additional information is also provided on unique features and application notes on various flume types. Source: Teledyne ISCO Open Channel Flow…

Monitoring the flow of sewage is dirty and smelly, but that doesn’t mean it has to be hard! Many of the problems encountered in measuring surface and / or irrigation waters – high solids content, debris, the need to minimize head loss – are also present in sanitary…

One question that comes up again and again is: Can Parshall flumes have the flow spill off the end? The answer is yes! While initially designed for installation in irrigation channels and canals, the Parshall flume has been shown to be well suited for use on free-spilling…

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…

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.

Parshall flumes should not be placed at an elevation lower than that of the channel being measured for fear of inadvertently inducing supercritical flow in the flume (and a hydraulic jump) in the flume. Field observations have shown that supercritical flows can result in the…