Flumes

TRACOM offers seven types of flumes for open channel flow monitoring:

Each flume has its own advantages and disadvantages and it is recommended that before selecting a flume that the characteristics of each flume be considered.

Parshall

  • Most widely used type of flume for permanent installations
  • Standard design conforms to U.S. Department of the Interior, Bureau of Reclamation, Water Measurement Manual
  • Available in throat widths of 1” to 180”
  • Resistant to the effects of submergence
    • 50% for 1” - 3” flumes
    • 60% for 6” and 9” flumes
    • 70% for 12” - 96” flumes
    • 80% for 120” flumes
  • Self-cleaning in most circumstances (not recommend for sanitary use in 1” and 2” sizes)
  • Available in nested configurations
  • Available with end adapters to connect to existing pipe
  • Simple flow meter calibration
  • Maximum flow rates from 85.3 GPM – 467,200 GPM with standard wall heighths
  • Installation requires drop in conduit invert from inlet to outlet

Palmer-Bowlus

  • 4”-108” sizes available (sized by throat width)
  • Three primary styles:
    • 4D+1” (permanent style with integral approach section)
      Point of measurement inside of the flume
    • 2D+1” (short sectioned flume with only the trapezoidal ramp)
      Point of measurement upstream of the flume
    • Insert style (2D+1” length but no end flanges and O.D. of flume is I.D. of pipe)
      Potential problems with accuracy due to reduced flume width
  • Available with bulkheads to connect to existing pipe
    • 4D+1” – inlet and outlet
    • 2D+1” – outlet only
    • Insert style – N/A
  • No invert drop required
  • Easily installed in manholes or round bottom channel
  • Maximum flow rates from 55.2 GPM – 198,535 GPM
  • Proprietary design varies from manufacturer to manufacturer
  • Smaller useful range of flows
  • Sedimentation at lower flow velocities
  • Requires 25 straight run pipe diameters upstream

HS / H / HL-Type

  • Standard design conforms to U.S. Department of Agriculture, Field Manual for Research in Agricultural Hydrology
  • Available in a wide range of sizes from 0.4’ HS – 4.0’ HL
  • Developed for agricultural runoff
  • Approach section and inlet bulkhead available for connection to existing pipe
  • Simple flow meter calibration
  • Flat bottom for self-cleaning of small debris
  • Wide range of flows
  • Maximum flow rates from 36.0 GPM – 52,509.6 GPM
  • Discharge must be unimpeded or spill freely from flume
  • Cannot operate under submerged conditions
  • Require 3-5 times the maximum head in straight channel upstream of the flume

Trapezoidal

  • Initially designed to measure flows in irrigation channels
  • Conforms to the normal shape of ditches (minimizing transition)
  • Operates under higher degrees of submergence than Parshall flumes
  • Straight through bottom permits the passage of debris
  • Excellent usable head at low flow rates
  • Maximum flow rates from 43.0 GPM 663.8 GPM (Small to Extra Large 60 Degree V Trapezoidal)
  • End adapters are available for Small, Large, and Extra Large 60 Degree V Trapezoidal flumes to connect to existing pipe

Cutthroat

  • Parshall flumes except with flat bottom and no extended throat
  • Developed for use in flat gradient channels
  • Operates satisfactorily under both free and submerged flow conditions
  • Sized by flume length and throat width
  • Simpler construction than Parshall flumes
  • Simple flow meter calibration
  • Flat bottom for self-cleaning of small debris (1 and 2 throat widths not recommended for sanitary flows)
  • Maximum flow rates from 52.6 GPM 43,494 GPM
  • Not available with standard end adapters to connect to existing pipe
  • Most common uses include stream gauging and flow splitting

RBC

  • Developed for use in small furrows and unlined canals
  • Simple construction
  • Scaled versions of the general flume
  • Five throat widths (50mm, 75mm, 100mm, 150mm, 200mm)
  • Ideal for very low flow rates
  • Maximum flow rates from 22.98 GPM 790.79 GPM
  • Inlet and outlet wingwalls recommended for use in unlined canals
  • Portable
  • Caution should be used in flows with high solids content

Montana

  • Design is a Parshall flume with the throat and discharge sections removed
  • Uses the same discharge table as a similarly sized Parshall flume
  • Standard design conforms to U.S. Department of the Interior, Bureau of Reclamation, Water Measurement Manual
  • Available in throat widths of 1 to 144
  • Self-cleaning in most circumstances (not recommend for sanitary use in 1 and 2 sizes)
  • Available in nested configurations
  • Available with inlet end adapter to connect to existing pipe
  • Simple flow meter calibration
  • Maximum flow rates from 85.3 GPM 467,200 GPM
  • Cannot withstand any degree of submergence
  • Not commonly used

If you would like additional information, pricing, or assistance in sizing and specifying a flume, please fill out and submit our information request form.