Fiberglass (FRP / GRP) Parshall Flumes are the default material for most Parshall Flume applications - from stream gauging to wastewater treatment plants.  Parshall Flumes are available in fiberglass in sizes from 1 to 144-inches.  Larger than this, and concrete construction tends to be more economical.

Fiberglass Advantages

Typically constructed of polyester resins, fiberglass Parshall Flumes are lightweight, corrosion-resistant, economical, can have tight dimensional tolerances, and have considerable configuration flexibility.    

Light Weight

Fiberglass Parshall Flumes are about 1/2 the weight of comparable steel construction flumes and are about the same weight as aluminum construction flumes. Their light weight makes fiberglass Parshall Flumes particularly suitable for 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, vinyl esters (or epoxies) resins can be used, although it is usually more cost-effective to use stainless steel construction. It is important when using alternative resin systems also to match the gel coat to the resin system.

Economical

With standard polyester construction, fiberglass Parshall Flumes are an economical choice - priced between galvanized / painted steel and aluminum / stainless steel construction.

Vinyl ester construction typically falls between the price of 304 and 316 stainless steel construction.  While epoxy construction is still yet higher.

Dimensional Tolerances

The dimensional tolerances for fiberglass Parshall Flumes are dependent upon the dimensional accuracy of the molds used.  The tighter a mold's tolerances are, the better the flume's tolerances will be.  

For Openchannelflow fiberglass Parshall Flumes, the following dimensional tolerances are typical:

Throat

• 1/16-inch [1.59 mm] (12-inch or smaller Parshall Flumes)

• 3/32-inch [2.38 mm] (18-24-inch Parshall Flumes)

• 1/4-inch [6.3518 mm] (36-96-inch Parshall Flumes)

• 1/2-inch [12.7 mm] (120-144-inch Parshall Flumes)

Other Flume Dimensions

• 1/8-inch [3.18 mm] (24-inch or smaller Parshall Flumes)
• 1/2-inch [12.7 mm] (36-96-inch Parshall Flumes)
• 1-inch [25.4 mm] (120-144-inch Parshall Flumes)

The above dimensions are within the +/-2% of nominal required by ASTM D1941-91(2013) Standard Test Method for Open Channel Flow Measurement of Water with the Parshall Flumes.

Configuration Flexibility

Openchannelflow fiberglass Parshall Flumes are available with a wide selection of accessories and mounting / end configuration options.