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Trapzoidal flume intersecting a creek

Plasti-Fab FRP Flow Measurement Products

As a leader in the flume fabrication revolution that began over forty years ago, Plasti-Fab has thousands of flumes installed in corrosive environments around the world.

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As a leader in corrosion resistant equipment for fluid measurement and flow, Plasti-Fab has thousands of Packaged Metering Manholes, Gauges, H Flumes, Palmer-Bowlus Flumes, Parshall Flumes, and Trapezoidal Flumes installed in corrosive environments around the world. Plasti-Fab products are fabricated from highly corrosion resistant composite fiberglass reinforced plastic (FRP) to combat corrosion. Plasti-Fab is recognized around the world as an experienced innovator providing composite solutions for municipal and industrial fluid measurement and management applications.

  • Fiber Glass Systems Specialized and Fiberglass Reinforced Plastics
Angled view of a new metering manhole, on wooden stand

Packaged Metering Manholes

Key Features

  • Composite FRP is extremely resistant to chemicals, saltwater, corrosive soils, ground water and electrolysis
  • Weighs only a fraction of concrete and steel structures
  • Strong – FRP is pound-for-pound much stronger than steel
  • Flumes with precise throat dimensions for accurate flow measurement
  • Premium grade Isophthalic white gel coat interior to resist bacteria and maximize illumination for safety, and gray exterior Minimum 1/2” wall thickness 48”, 60” and 72” diameter barrels standard – custom sizes available
  • Ladder, SS US brackets, and bubble tubes all designed/manufactured in house
Plasti-Fab gauge standing up straight


Key Features

  • Standard 1/4” thickness with custom thicknesses available
  • Premium grade isophthalic gel coat for long term corrosion resistance
  • “S” style stencil gauge with large block lettering for easy reading
  • “P” style gauge for smaller applications with various lettering styles available
  • Letter / numeral height and markings customized for each application
  • Impact resistant
New, unused H Flume in a facility

H Flumes

Key Features

  • Precise throat dimensions for accurate flow measurement
  • Designed with a usable range of more than 100:1
  • Standard 1/4” wall thickness
  • Free standing with up to 30” of Water Depth
  • Premium Grade Isophthalic Gel Coat for long term corrosion resistance
  • Head Gauge for visual fluid level check
  • Reinforced with engineered box rib design for strength on larger sizes
Palmer-Bowlus Flume connected to machinery, with grassy field and a mountain in the backgroumd

Palmer-Bowlus Flumes

The Palmer-Bowlus flume is well know in the sanitary field, and has been used in the Los Angeles area for over 60 years. It's primary application is in pipelines, in round bottom channels or in manholes where it is often preferred because of cost and ease of installation that can minimize construction expense.

Parshall flume outside a building

Parshall Flumes

Used in monitoring sewage, plant effluent, storm water and irrigation water the Parshall flume is still the best known and most widely used for permanent installations. It is available in throat sizes from 1 inch to 12 feet. Parshall flumes are available with numerous accessories and adaptations to match your flow and installation requirements. Made of fiberglass reinforced polyester (FRP) Plasti-Fab Parshall flumes offer optimum corrosion resistance and are the industry leader in measuring flow. For extremely severe industrial effluents they are also available in Vinyl Ester, stainless steel or other special materials as needed.

Trapzoidal flume installed in a creek, with a wire-link fence intersecting the creek

Trapezoidal Flumes

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 gauge 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.

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