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Openchannelflow Fiberglass Trapezoidal Flume measuring runoff at a utilityFiberglass (FRP / GRP) Trapezoidal Flumes are the most economical Trapezoidal flumes for a wide range of applications - from industrial effluent monitoring to stream gauging.  

Fiberglass Advantages

Typically constructed of polyester resins, fiberglass Trapezoidal flumes are light weight, corrosion resistant, economical, can have tight dimensional tolerances, and have considerable configuration flexibility.    

Light Weight

Fiberglass Trapezoidal flumes are about 1/2 the weight of comparable steel construction flumes and about the same weight as aluminum flumes. Their light weight makes fiberglass Trapezoidal flumes particularly suitable for use in remote watershed / catchment monitoring applications where flume weight is an issue.

Corrosion Resistance

Polyester resins are suitable for most surface water, industrial discharge, and wastewater applications where the flow stream may be mildly acid or basic and at atmospheric temperatures.  For more aggressive / higher temperature applications, alternative resin systems (usually vinyl esters or epoxies) can be used, although it is usually more cost effective to use stainless steel construction.


With standard polyester construction, fiberglass Trapezoidal flumes are the most economical choice - costing less than galvanized / painted / or stainless steel construction.

Dimensional Tolerances

For any fiberglass product, the dimensional tolerances are greatly dependent upon the dimensional accuracy of the molds from which they are produced.  For Openchannelflow fiberglass Trapezoidal flumes, the following tolerances are typical:

  • 1/16-inch [1.59 mm] (dimensions 12-inches or smaller)

  • 3/32-inch [2.38 mm] (dimensions 18-24-inches or smaller)

  • 1/4-inch [6.3518 mm] (dimensions greater than 36-inches)

Configuration Flexibility

Openchannelflow fiberglass Trapezoidal flumes are available with a wide array of accessories and mounting / end configuration options.

More About Fiberglass (FRP) Trapezoidal Flumes