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Dataloggers, Sensors & Control Systems

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Flumes and Weirs

Fiberglass and Steel Flumes and Weirs

We sell, design and install many different styles and types of flumes or weirs. Flumes and weirs are available in steel or fiberglass. We can also be hired to design and install concrete flumes or weirs into your designated canal, stream or river.

Winflume is a freeware program that designs ramp flumes and is available by clicking here.

Here is a link to the USBR Water Measurement Manual on-line, you will find a lot of useful information on the measurement of water. (Bureau of Reclamation)

Click here to get our Flumes Brochure.
Click here for our Water Measurement Brochure.

Learn about Stilling Wells

Ramp Flume - Replogle Flume or Long-Throated Flume

The ramp flume is a very popular flume used mostly in irrigation applications. It is a flume that functions more like a weir. It is often used in areas with low drop (flat ditches). We offer a galvanized steel ramp flume that is made by Nu-Way flume, in addition, we can build any size of ramp flume from steel or concrete. There are currently 4 pre-made sizes available. (see table below) The size references the maximum amount of flow that the flume can measure. You can download a brochure below that gives dimensions and explains more about the ramp flume. These flumes are generally in stock and ship within 7 days of an order, but please check with us for stock status.

Using ramp flume design software we can design and build any size ramp flume to meet your needs. We can build flumes in steel or concrete. We can also create the drawings based on your ditch and flow requirements and you can arrange to build your flume on your own.

ramp flume with stilling wellramp flume installed concrete ramp flume

(click the images to enlarge)

Max Flow Rate (cfs) Throat Width (in.) Length x Height (in.) Shipping Weight Approx.
3.5 12-1/8 47-1/2 x 14-7/8 62 lbs (UPS)
7.0 24-1/8 47-1/2 x 14-7/8 86 lbs (UPS)
10.0 36-1/8 47-1/2 x 14-7/8 108 lbs (UPS)
20.0 30-1/8 80 x 26 400 lbs (Freight)


parshall flumeParshall Flume (Steel or Fiberglass)

The Parshall Flume has been the most widely used type of flume for fixed flow monitoring installations. Parshall Flumes are sized by throat width, and conform to standardized dimensions published in the U.S. Department of the Interior, Bureau of Reclamation.

We offer all standard sizes made in fiberglass or steel. These flumes take 3 weeks on average to build, contact us for a quote.

parshall flume flow rates












Table above comes from ISCO Open Channel Flow Handbook

DrawingsDrawings & Specifications for Parshall

Steel Parshall

cutthroat flumeCutthroat Flume - Steel or Fiberglass

The Cutthroat flume was developed and studied by Utah State University Water Research Lab in approx. 1967. (see report)

The most obvious advantage of a cutthroat flume is economy, since fabrication is facilitated by a flat bottom and removal of the throat section. Another advantage is that every flume size has the same wall lengths in both the entrance and exit sections, allowing the same forms or patterns to be used for any flume size. The use of a consistent geometric shape allows accurate predictions of discharge ratings for intermediate flume sizes.

cutthroat installed imageThe cutthroat flume consists of only a converging inlet section and a diverging outlet section. (see picture on left) The one varying dimension is the flume size or throat width. These flumes are able to operate under free flow conditions with submergence ratios up to 79-88% depending upon the flume size. If the flume becomes submerged you can make a second measurement at the effluent and adjust the flow equation to gain an accurate flow reading.

Available Sizes & Flow Rates:

Flume Length In. Throat Width In. Flume Depth in. Max Flow GPM/CFS
18 1 6 56 / 0.12
18 2 6 114 / 0.25
18 4 6 223 / 0.49
18 8 6 474 / 1.05
36 2 12 322 / 0.71
36 4 12 655 / 1.46
36 8 12 1,333 / 2.97
36 16 12 2,712 / 6.04
54 3 18 866 / 1.93
54 6 18 1,763 / 3.92
54 12 18 3,588 / 7.99
54 24 18 7,301 / 16.26
108 12 36 6,932 / 15.44
108 24 36 14,106 / 31.42
108 48 36 28,699 / 63.94
108 72 36 43,494 / 96.9

download cutthroat drawingDownload Cutthroat Drawing

Other Flumes Available:

  • H-Flume
  • Trapezoidal Flume
  • Packaged Metering Manholes

Weirs: V-Notch, Rectangular, Triangular, Cipolletti, Box Weirs

A weir, as defined in the USBR measurement manual, is simply an overflow structure built perpendicular to an open channel axis to measure the rate of flow of water. Inspecting and checking the critical parts of weir structures for degradation and improper operation are easy.

A properly built and operated weir of a given shape has a unique depth of water at the measuring station in the upstream pool for each discharge. Thus, weirs can be rated with respect to an upstream head relative to the crest elevation versus discharge, and equations or tables which apply to the particular shape and size weir can be generated. The crest overflow shape governs how the discharge varies with head measurement.

USBR Weir image rectangular weirThe weir is one of the oldest structures used to measure the flow of water in open channels. Several rating equations were developed for standard rectangular contracted weirs by different investigators. Generally, the data of each investigator are within +1.5 to +2.5 percent with respect to their individual equations, but comparisons of the various equations differ as much as several percent (King and Brater, 1976; Ackers et al., 1978).

We offer weirs made of fiberglass or steel. We can design a weir for you that can be built of concrete on-site. To learn more about weirs and for assistance in selecting the correct type please contact us for a no-obligation consultation.

weir box with v-notchPhoto is from USBR Measurement Manual (Rectangular Weir)

Box weirs are also available and are convenient in many applications. They are often used when an application requires a control section and baffles to calm and control the water before being measured at the weir plate. A weir box can be installed with inlet and outlet pipe adapters as shown in the image on the right.

There are a variety of weir types, based on shape.

weir types    
Click image above for a larger view
Image is borrowed from the USBR Measurement Manual

flow probe in useFlow Probe

For flow spot checking take a look at the Flow Probe. The Flow Probe is a velocity meter. It is simple to use and inexpensive in comparison to other flow and velocity meters. We use the Flow Probe to check velocity in open channels and to create stream flow rating tables.

More Info..