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Weir Manholes

Fiberglass Flow Measurement Manhole with Aluminum Hatch Top and 90-degree V-Notch Weir PlateWhile the range of flumes offered by Openchanneflow is extensive, there are times when a weir is a better fit for a buried pipe flow application.  Until now the question was how best accurately install a weir in a below grade application.  Openchanneflow has introduced a line of packaged fiberglass Weir Manholes to solve this problem.

Openchannelflow’s Weir Manholes integrate the same v-notch weir plates used in our portable weir and weir box applications with fiberglass manhole barrels to provide a single-piece, factory-integrated, packaged, watertight, and corrosion resistant solution that requires requiring minimal installation time and virtually no maintenance.  Dig It!  Drop It!  Done!

For owners fiberglass Weir Manholes provide:

  • Confidence that the weir is sized, fabricated, and installed correctly to ensure accurate flow measurement (no questions from your monitoring agencies)
  • Single source responsibility (no finger pointing between subcontractors)
  • Low maintenance and repair costs due to the corrosion resistance of fiberglass to even the most aggressive of environments
  • Minimal installation downtime

For contractors fiberglass Weir Manholes provide:

  • Single source responsibility (no finger pointing between subcontractors)
  • Confidence that the weir is sized, fabricated, and installed correctly to ensure accurate flow measurement (happy customers)
  • Virtually no warranty repairs when installed according to Openchannelflow.com’s instructions.  Dig a hole, drop it in, and your done.  
  • Industry leading FiberLock equipment warranty – up to 5 years!
  • Minimal installation downtime (minimizing pump around on active lines – better utilization of site equipment)

For consultants fiberglass Weir Manholes provide:

  • Single source responsibility (no finger pointing between subcontractors)
  • Confidence that the weir is sized, fabricated, and installed correctly to ensure accurate flow measurement (happy customers)
  • Industry leading equipment warranty – up to 5 years!
  • High levels of user satisfaction – users who have experience with fiberglass flow measurement manholes (flume or weir) almost exclusively specify their use on future projects – they are just that happy!

Openchannelflow.com offers a variety of manhole cover styles, diameters, and options to tailor our Weir Manholes to your specific needs.

Top styles include:

  • Full opening domed top for maximum access
  • Flat cover aluminum hatches for pedestrian areas / low profile installations
  • Large diameter opening highway loading reducers tops (using customer supplied grade rings, cover, and frame)
Manhole diameters available are:
5’ [152 cm], 6’ [183 cm], 7’-8” [234 cm]1

The 4’ [122 cm] manhole diameter available with our flume based flow measurement manholes, although available upon request, is typically too small to allow the formation of a correct weir pool for any but the smallest of flows.  As such it is not typically used in Weir Manhole applications.

Each unit comes as a single, watertight piece with the following features:
  • Weir carrier with one (1) standard weir plate mounted
    • Weir plates available include:  22-1/2° V , 30° V, 60° V, 90° V, 120° V, and 12” Cipolletti
  • Corrosion resistant interior barrel surface
  • OHSA-compliant fiberglass ladder with non-slip ladder rungs
  • Integrated cover (see above)
  • Closed base
  • External base mounting / anti-flotation flange with cushioning pad
  • Inlet / outlet piping with flexible couplings for quick pipeline connection (flanges and caulking collars optional)
  • Exterior corrosion resistant gel coat barrier with U.V. inhibitors

In addition, Openchannelflow offers a wide array of optional accessories to help you customize your flow monitoring manhole to fit your specific needs, including:

  • Integral fiberglass benches
  • Additional manhole thru-wall couplings (for power / controls / etc.)
  • Full and half diameter fiberglass grating platforms
  • General purpose and hazardous location lighting
  • Powered and unpowered ventilation
  • Equipment shelves and mounting panels
  • Two-piece construction for ease of handling

1Aluminum hatch and highway loading top styles only.