When you need to measure open channel flow, a flume is the best option all around. Learn about the different types of flumes, what goes into their application, and what you need to know about selecting flumes for flow rate measurement and management.
Selecting Flumes for Flow Management
Selecting a flume for flow management involves a number of advantages and disadvantages, but the benefits far outweigh the drawbacks. If you’re deciding between a flume and a weir, for example, you’ll find that flumes cost more and maybe a bit more difficult to install. They also, however, require less maintenance, are usually self-cleaning, have lower head loss, and can be flexible in measurement with high accuracy.
Flumes come in many different types and configurations. When installed properly, they are compact and have strong submergence resistance, and their accuracy is much less affected by approach velocity than the typical weir. In short, they carry a lot of benefits.
Types of Flumes
When choosing a type of flume for your flow management needs, you’ll look at six general flumes. These are:
- Parshall Flume (including Short Parshall/Montana)
- H, HS and H
- Palmer-Bowlus
- Trapezoidal
- Cutthroat
- RBC
The Most Common Flumes
Parshall flumes are the most commonly known and used flumes. They’re available in many throat widths and offer up to 80% submergence transition depending on the size you choose. They can be installed to allow flow spill-off at the end or to let the flow rejoin the inline channel. They have an hourglass shape and can be raised above the channel or placed in a downstream channel.
Montana, or Short Parshall, flumes are based on the Parshall flume but remove the discharge and throat sections. They can only be used to allow discharge to free spill. These are rarer and not widely used.
Cutthroat flumes can be thought of as a Parshall flume with a flat bottom and without a long throat. They don’t require invert drop and have greater submergence transitions while allowing solid passage. Their downside is that they’re sensitive to upstream use.
H, HS, and HL flumes are commonly used in agricultural concerns but can also be found in industrial applications. They come in multiple sizes with dimensionless designs. They require complex equations for discharge and are built to allow free-spilling discharge.
Other Types of Flumes
Palmer-Bowlus long-throated flumes are designed for sanitary flow measurement in existing conduits. They come in many styles for existing, retrofitting or new applications. You will need to be sure that the flow tables match your needs, as they are not standardized. They can be prone to sediment collection.
Trapezoidal flumes are built for irrigation channels. They’re designed to allow solids to easily pass through, and their flat bottom combined with a high submergence transmission means they are good to install in flat grades. They have solid accuracy in measuring low flow rates.
RBC flumes are long-throated and built for ditches and furrows. They have high submergence transitions and good flow accuracy in a range of sizes with dimensionless design. They can be prone to sediment collection.
Call Tracom for Flume Selection
Tracom is your source for a wide selection of quality fiberglass flumes for flow management. Check out our website and get in touch with us today for more information or to place your order.
