Flumes Concrete Cutthroat

Fiberglass or Steel Flumes

Flumes are an accurate and effective way to measure flow rate in open channel applications. All flumes work by measuring how much the water rises in level before an obstruction (the flume) of known dimensions and shape. In this sense, they are very similar to weirs, but do not create so large a change in head.

There are many different types of flumes, we usually recommend either the Ramp flume or Cutthroat flume for most irrigation sites, but the Parshall flume is also a good choice. All of these flumes are relatively easy to install, come in a wide range of sizes, and provide good accuracy. We offer other types of flumes, such as the H-flume or Trapezoidal flume, these are generally used in specific applications and may be a good choice for your needs.

We provide a variety of sensors, dataloggers, and data retrieval systems (including via internet) for monitoring flow rate remotely. Please call us at (435) 755-0774 to learn more, we are remote data and control experts.

Ramp Flume

steel ramp flume

(most frequently recommended)

The Ramp flume (also known as a broad-crested weir) is a very popular flume used primarily in irrigation applications. It is a flume that functions somewhat like a weir. It is often used in areas with low drop (flat ditches). We carry 4 pre-made sizes (see table), and we can design and build custom ramp flumes of any size, including larger flumes made of concrete. Our pre-manufactured ramp flumes are usually less expensive than other comparable flumes.

Our smaller Ramp flumes ship in a compact form and can be assembled on site. Assembly is easy and usually takes less than an hour with basic tools. This makes our ramp flumes easier to ship and handle than most other flumes, which must be shipped pre-assembled. Stilling wells can be ordered in a variety of materials and sizes. We can also provide a stilling well port on the side of the flume so that you may provide your own stilling well on-site.

We frequently recommend ramp flumes for a number of reasons:

  • Best flume for flat ditches
  • Less likely to clog
  • Easy to install, assemble, and transport
  • Can be designed and built to custom specifications
  • Usually most affordable of all options
Standard Sizes
Max Flow Rate (CFS / GPM) Throat Width (in.) Length x Height (in.) Shipping Weight Approx.
3.5 / 1600 12-1/8 47-1/2 x 14-7/8 62 lbs
7.0 / 3100 24-1/8 47-1/2 x 14-7/8 86 lbs
10.0 / 4500 36-1/8 47-1/2 x 14-7/8 108 lbs
20.0 / 9000 30-1/8 80 x 26 400 lbs (Freight)
 Custom  Varies Varies Varies

For ordering and information call (435) 755-0774 or email info@inmtn.com.

PDF Brochure

Cutthroat Flume

The Cutthroat Flume was developed by Utah state University Water Research Lab in approx. 1967 (see report). It is sometimes called a flat-bottom flume. It is resistant to submergence, and can still be used when submerged by taking a second measurement at the effluent. We sell cutthroat flumes in steel and fiberglass, and in a variety of standardized sizes (see table).

Advantages of Cutthroat Flumes
  • Can be installed in flat ditches
  • Does not clog as easily as a Parshall flume (larger throat sizes)
  • Easy to install
  • Resistant to submergence
  • Cost effective
Sizes
Flume Length (in.) Throat Width (in.) Flume Depth (in.) Min Flow (CFS / GPM) Max Flow (CFS / GPM)
18 1 6 .0008 / .3536 .1113 / 49.95
18 2 6 .0015 / .6779 .2134 / 95.76
18 4 6 .014 / 6.28 .445 / 200
18 8 6 .029 / 12.8 .908 / 408
36 2 12 .003 / 1.30 .719 / 323
36 4 12 .021 / 9.47 1.46 / 655
36 8 12 .043 / 19.3 2.97 / 1,333
36 16 12 .087 / 39.2 6.0 / 2,711
54 3 18 .018 / 8.21 1.93 / 865
54 6 18 .037 / 16.8 3.94 / 1,767
54 12 18 .076 / 34.0 8.0 / 3,588
54 24 18 .153 / 68.5 16.1 / 7,220
108 12 36 .096 / 43.3 19.4 / 8,718
108 24 36 .196 / 87.9 39.5 / 17,711
108 48 36 .399 / 179 80.4 / 36,094
108 72 36 .606 / 272 122 / 54,801

For ordering and information call (435) 755-0774 or email info@inmtn.com.

Parshall Flume

The Parshall Flume has been the most widely used flume for fixed flow monitoring installations. Parshall flumes are sized by throat width, and conform to standardized dimensions published by the U.S. Department of the Interior, Bureau of Reclamation. We offer all standard sizes both in fiberglass and steel. They take 3-4 weeks on average to build.  Parshall flumes are often installed incorrectly and require additional adjustments to their flow equation to be as accurate as possible.  Due to this we often recommend using a different style flume in irrigation applications.  We can offer consultation as to which type of flume will best fit your needs, or make recommendations on how to improve the measurement at a site that already has a Parshall installed.

Advantages of Parshall Flumes
  • Very accurate in some applications
  • Remain accurate under low flow conditions (wide operating range)
  • Can continue to measure flow when submerged
Limitations of Parshall Flumes
  • Prone to clogging in sizes below 1 ft. (when used in irrigation)
  • More difficult to install in very flat ditches
  • Often creates more upstream head than other flumes
Steel parshall flume
Parshall Flume Sizes
Throat Width Min. head (ft) Min flow (CFS / GPM) Max. head (ft) Max flow (CFS / GPM)
1 in. 0.10 0.010 / 4.28 0.70 0.194 / 87.3
2 in. 0.10 0.019 / 8.55 0.80 0.478 / 215
3 in. 0.10 0.028 / 12.6 0.80 1.15 / 516
6 in. 0.10 0.054 / 24.3 1.50 3.91 / 1,750
9 in. 0.10 0.091 / 40.7 2.00 8.87 / 3,980
1 ft. 0.10 0.120 / 54 2.50 16.1 / 7,240
1.5 ft. 0.10 0.174 / 78 2.50 24.6 / 11,000
2 ft. 0.15 0.423 / 190 2.50 33.1 / 14,900
3 ft. 0.15 0.615 / 276 2.50 50.4 / 22,600
4 ft. 0.20 1.26 / 567 2.50 67.9 / 30,500
5 ft. 0.20 1.56 / 698 2.50 85.6 / 38,400
6 ft. 0.25 2.63 / 1180 2.50 103 / 46,400
8 ft. 0.25 3.45 / 1550 2.50 140 / 62,600
10 ft. 0.30 5.74 / 2570 2.75 199 / 89,200
12 ft. 0.33 7.93 / 3560 3.50 347 / 156,000

For ordering and information call (435) 755-0774 or email info@inmtn.com

Drawings & Specifications
Parshall Flume Fiberglass

Other Flumes

These flumes are more specialized than the others listed above, but we sell and support all of them. Feel free to ask us for details.

H-Flume

Because of its V-shaped discharge, the H-Flume is accurate in both high and low flow conditions. H-flumes must be elevated above the effluent so the water can freely spill out of the flume.

Trapezoidal Flume

The Trapezoidal Flume is similar to the Cutthroat (flat-bottom) Flume, but has outward sloping walls. And like the H-flume, it is designed to be accurate in both high and low flow conditions. These are often used in irrigation or in any open channel where the flow rate may vary widely.

Palmer-Bowlus Flume

The Palmer-Bowlus Flume was designed for measuring wastewater in conduits, and they are often installed in manholes. They are very accurate, but have a smaller range of useful flow rates compared to other flumes.

flumes palmer-bowlus h flume trapezoidal

Sensors & Accessories

We have a variety of sensor systems used for monitoring, logging and reporting flow rate through a flume or weir. Most of these sensors (depending on the specific model) send a signal that is recorded by a datalogger, and the data can be retrieved later in person. Or, it can be transmitted live via radio or internet, allowing you to monitor flow rates with a radio receiver, or even from a cell phone or web browser.

Water Level Sensor

Sensors

Sensors for monitoring flumes and weirs, including ultrasonic sensors, floats and pulleys, pressure transducers, bubblers, and radar level sensors.

Datalogger monitoring system

Dataloggers & Telemetry

Hardware for recording sensor data and transmitting it, including enclosures, solar panels, batteries, etc.

Custom Stilling Well

Stilling Wells

Hardware for recording sensor data and transmitting it, including enclosures, solar panels, batteries, etc.