The Montana Flume is a modification of the widely used Parshall Flume.  The flume takes it shape from the hourglass of the Parshall, but omits both the throat and discharge sections - leaving only the flat-floored converging section.  With the deletion of the throat and discharge sections, the Montana Flume requires free-spilling flow off the end of the flume.

Montana Flumes are inexpensive and accurate ways of measuring the flow of water in a variety of applications.  

Just like the Parshall Flume, the Montana Flume is available in 22 different sizes – although, in practice, Montana Flumes larger than 48-inches in size are rarely used.

Like the Parshall flume on which they are based, Openchannelflow manufacturers Montana Flumes in:

• Aluminum
• Fiberglass (FRP)
• Galvanized Steel
• Stainless Steel

Of the materials, fiberglass is most commonly used to measure sanitary / municipal sewage flows, while stainless steel is most common for discharges with corrosive chemicals, high temperatures, or abrasive solids or where vandalism is a concern. Where only lightweight and abrasion resistance are sought, aluminum is an excellent material choice.  Finally, for water rights and irrigation applications, most Parshall Flumes are made from galvanized steel.