Trapezoidal Flumes

Trapezoidal Flumes

Trapezoidal flumes fall into two principal groups, 60º V-notch flumes and larger trapezoidal flumes. The 60º V flumes have a sharp V-throat section similar to a V-notch weir and produce superior resolution for accurate flow measurement down to 1 gpm. The larger trapezoidal flumes, up to the 2 foot SRCRC flume, have flat floors and sloping sidewalls and can handle flows up to 32 MGD.

Trapezoidal Flumes Key Features

All Trapezoidal flumes exhibit similar flow characteristics, and have application advantages over other flumes and weirs.

  • The bottom is flat from entrance to exit for better head conservation.
  • Trapezoidal flumes do not require a free-fall discharge to operate correctly.
  • The staff gage and instrument mounting brackets are located within the flume and are factory installed.
  • The natural shape of the flume mimics many earthen and concrete-lined ditches. Little or no transition is required in these situations.

60° V Trapezoidal flumes provide the only practical means of obtaining good flow data on low and intermittent flow streams. This flume produces more readable head under 10 gpm than any other flume or weir. Plasti-Fab has demonstrated the flumes effectiveness in over 20 years of use by small industries, developments, parks and communities.

Problem Solving Adaptations:

Accessories and Instrument Set-ups:

    • Accurate flow measurement down to 1 gpm
    • Better resolution and repeatability especially below 0.2 ft. of head
    • No requirement for upstream pooling or downstream free-fall
    • Can operate up to 80 – 85 percent submergence with little or no loss of accuracy
    • The flat floor and sloping wall allows solids to pass through the throat without being trapped
    • 60º flume sizes are available to measure flows as high as 6200 gpm

Larger Trapezoidal flumes have a primary gage located at the H1 location for normal free flow operation, and a downstream gage at the H4 location for use in conjunction with submerged flow tables. We recommend that all flumes be designed and installed for free flow operation.

  • Adjustable stainless steel support brackets for all types of ultrasonic transducers
  • Molded side cavities and floor cavities for:
  • Stainless steel bubble pipes
  • Stainless steel sample pipes
  • Pressure transducers
  • Capacitance probes and s/s grounding plates
  • Stainless steel liftout brackets for pressure and pH probes
  • 2″ threaded tap for remote still well
  • 8″ and 12″ diameter attached still wells
  • Sealed ultrasonic mounting tube
    • Permanent installation in concrete or earthen channels
    • Free standing flumes with wing walls, end bulkheads or adapters for larger diameter pipes and channels
    • End adapters for piped installation – Small 60º V to 3 ft. 60º V flumes
    • Packaged Metering Manholes for below grade installation – Large 60º V to 3 ft. 60º V flumes
    • Tranquilizer racks and energy absorbing units to reduce velocity and turbulence
    • Surge boxes to handle possible surcharging at in-plant and sensitive locations –Large 60º and XL 60º V trapezoidal flumes
    • FRP grating or odor control covers
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