Glass-Steel, Inc.

Call now: 1.281.572.2211

industrial & municipal fiberglass fabrication


Physical Properties

Additional FLow Chart is shown on the PDF below

For a printable PDF version click the file below:

Vertically Cantilever Beam-Fixed one end


Spagco Parshall Flumes are constructed from a fiberglass composite constructed of two fiberglass skins with a polymer concrete core. All Spagco flumes have a total wall thickness of 1 ½”. Due to the high moment of inertia of the wall due to the thickness, no stiffeners or other braces are required. The superior strength of the sandwich panel construction allow the flume to act as the concrete form as the concrete trench wall are cast with no need for any internal bracing. All Parshall Flumes are made to same dimensions established by Dr. Ralph L. Parshall in 1922 and are shown in attached table #1 plus drawings #1 & #2. Spagco Parshall Flumes come standard with two built in gauges. The first gauge is set at a distance of 2/3 of the wall length of the approach side of the flume as measured from the start of the flume throat toward the inbound flow. This first gauge is for measuring the flow into the system. The second gauge is set at a point 2” back from the downstream edge of the throat of the flume. This gauge allows a quick visual check for determining whether the flow is in free flow or submerged flow. Table #2 indicates the flow rate in cubic feet per second under free flow conditions as well as the maximum height at gauge to as compared to the gauge #1 reading for free flow to exist. If the water level at gauge #2 is higher than indicated the incoming water in  a submerged flow condition and the chart will have to be adjusted to accommodate that flow. Spagco can also supply threaded inserts or mounting brackets for installing ultra sonic sensors or other flow measuring devices as required.

The dashed line in the above diagram indicates typical water flow profile for free flow

Tensile Strength                                                          8,700psimin ASTM D638
Flexural Strength                                                        18,000psi min ASTM D790 Flexural Modulus                                                                       1.0 x 106psi min ASTM D790
Compressive Strength                                                11,000psi min ASTM D695
Average Coefficient of Thermal Expansion               10.5 x 10-6 ASTM D696
Water Absorption % 24 hours                                   .10% ASTM D570    

Height of 1-1/2" flume wall is 36" inside depth per the following formula.


Four 8'0" throat flumes built with a tongue and groove connection in the middle for easier transport and installation


parshall flume flow rate

John Lindsay

P: (281) 572-2211

F: (281) 572-2212