How Much Do Fiberglass (FRP) Parshall Flumes Cost?

Fiberglass (FRP) Parshall Flume Since the Parshall flume is the most commonly applied flume in North America and fiberglass the most common material, it is not uncommon when talking with a customer for the first time to be asked: so how much does a fiberglass Parshall flume cost anyway?

Finding out this information can be difficult as Parshall flume manufacturers (like matress salesmen) and their representatives usually don't want this information to be known!

This article will attempt to answer this question, but keep in mind that with 22 sizes of Parshall flumes available these numbers will be general only – there are just too many flume sizes and configurations to cover!

Also, Parshall flumes (and flumes in general) are engineered devices. As such they should be selected and sized by knowledgeable individuals and not all flumes are suitable for all applications. Sanitary applications in particular can cause problems for the uninitiated.

Base / Plain Parshall Flumes

There are two pricing components in applying a flume: the flume itself and the flow transitions. Flow transitions are how the flow enters and exits the flume. This can be done by a formed channel, inlet / outlet end adapters, piping, etc.

For applications where the channel is existing (or will be formed), a base / plain Parshall flume may be suitable. Here, depending upon the flume size, the prices for base / plain Parshall flumes range from $680 to $40,900, with the most common sizes ranging in price from ~$2,500-$3,500 (see below):

9-inch $2,500
12-inch $3,020
18-inch $3,530

A caveat about forming transitions: Parshall flumes do require proper upstream conditions. A common cause of inaccurate flow readings in Parshall flume are poorly formed inlet transitions.

Parshall Flumes with End Adapters

End adapters are specially formed structures designed to transition flow into / out of a flume in a controlled manner. For Parshall flumes, end adapters are available for flume sizes up to 36-inches [91.44 cm], although in practice end adapters are not usually found on flumes larger than 24-inches [60.96 cm] in size.

A rule of thumb is that adding inlet and outlet end adapters doubles the cost of a Parshall flume.

While seemingly expensive (in comparison to a base or plain flume), end adapters take away many of the headaches surrounding transitioning flow into / out of a Parshall flume. This is particularly true of piped flows.

A further advantage of end adapters is that the inlet end adapter can be modified to mount flow conditioning structures (baffle plates, flow straighteners, manual screens, etc.) which would be difficult or impossible to accommodate into existing channels.

Parshall Flume Accessories

Parshall flumes are available with a wide variety of accessories. The can be generally grouped into:

End Connections
- End adapters (above)
- Manhole transitions
- Wing walls
Flow Conditioning (all require an inlet end adapters)
- Bar screens / trash racks
- Energy absorbers
- Flow straighteners
- Perforated plates
Flow/Level
- Bubbler tubes
- Staff-level gauges
- Stilling wells
- Ultrasonic sensor brackets
Parameter Monitoring
- Probe holders
- Probe wells
- Sampler tubes
Customization
- Custom colors
- Enclosures (great for green roof runoff flumes)
- Extended sidewalls
- Nested (dual range) flumes
- Recessed grating
- Replacement floors
- Sectioning

Depending upon the nature of the option and material of construction, pricing for the the above Parshall flume options can range from $100 to $3,000 with the end connections and customization options the more expensive.

Remember that the total cost of a fiberglass Parshall flume with hinge upon a number of factors, including: quality, configuration, end connections, accessories, support, and warranty length.