Open Channel Flow Equipment

Packaged Metering Manhole

Open Channel Flow
Wastewater Equipment

Packaged Metering Manhole

Openchannelflow fiberglass Packaged Metering Manholes (PMMs) solve the difficult problem of measuring piped flows below grade.  Starting with our industry-leading fiberglass manhole tube, Openchannelflow integrates: a flow device (flume, weir, or mag meter), cover, base, and access ladder.

The result is a single-piece, watertight, and corrosion-resistant structure from which operators can accurately (and safely) measure and sample flows.


Openchannelflow Packaged Metering Manholes can include different flow devices to measure both open and closed pipe flows.

  • Flumes
  • Weirs
  • Mag Meters
  • Venturi tubes

Strength Built In

At the core of each Openchannelflow Packaged Metering Manhole is our fiberglass manhole tube.  While manhole configurations may differ, all Openchannelflow manhole tubes meet or exceed both ASTM D3753 and AASHTO H-20 standards.  The interior of these tubes is smooth and corrosion-resistant.  The light tan coloration of the tube helps to maximize visibility inside the manhole.

Unlike competing Packaged Metering Manholes, which claim to meet ASTM D3753, the interior of Openchannelflow Packaged Metering Manholes are pigment / gel coat free – allowing for visual inspection and quality control of the tube during and after production and meeting the requirements of D3753.


A variety of top styles are available with Openchannelflow Packaged Metering Manholes, including:

  • Domed Fiberglass (for non-vehicle / traffic areas)
  • Aluminum Covers (for pedestrian traffic areas)
  • H-20 Traffic Reducers (for use with standard grade rings, frames, and covers)
  • Open Top (for custom applications where the manhole top needs to be open or provided with a fiberglass grating)

Openchannelflow Packaged Metering Manholes are available in diameters from 48 to 96-inches [1.22 to 2.44 m] and in depths up to 35-feet [10.7 m].

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P.O. Box 397
W166 N11965 Fond du Lac Ave.
Germantown, WI 53022