Montana Flume Dimensions
The dimensions for the Montana Flume are based upon those of the Parshall Flume from which it's derived.
The dimensions and tolerances of Parshall Flumes have been standardized in several national / international standards and authoritative publications:
- ASTM D1941-91 (Reapproved 2013) Standard Test Method for Open Channel Flow Measurement of Water with the Parshall Flume
- ISO 9826:1992 Measurement of Liquid in Open Channels - Parshall and SANIIRI Flumes
- JIS B7553 Parshall Flume Type Flowmeters
- The Parshall Flume: Instructions for Installation and Table of Discharge, State Engineer of Colorado
The Montana Flume is defined in:
- MT 9127 (AG) Montana (Short Parshall) Flume (Part 1), Montana State University
- MT 9128 (AG) Montana (Short Parshall) Flume (Part 2), Montana State University
- Water Measurement Manual, 3rd Edition, United States Department of the Interior, Bureau of Reclamation
It's critically important to note that although Montana Flumes share a standard layout, they are NOT scale models of each other – they are empirical devices for which flow rate investigations were conducted.
The use of non-standard flume sizes is HIGHLY discouraged, and the dimensions and flow accuracies of such devices should be considered suspect.
Dimensional Tolerances
ASTM D1941 requires that Parshall (Montana) Flumes have dimensions within +/-2% of nominal, while JIS B7553 requires tolerance of +/- 1-1.5% depending upon flume size.
Parshall (Montana) Flumes with dimensions outside of these ranges should be considered non-conforming and should be either replaced for field rates.
