parshall flume การใช้

• A modified version of the Venturi flume is the Parshall flume.
• Not all Parshall flumes have the energy-recovering divergence section.
• Influent wastewater is received and flow rate is measured using a Parshall flume.
• Where submergence is possible, a full length Parshall flume should be used.
• By the 1960's several different companies began to commercially offer Parshall flumes.
• As with any Parshall flume, flumes varying from the standard dimensions flumes should be individual rated.
• Parshall flumes are much more efficient than standard flumes and generate a standard wave to effect a measurement.
• There are two conditions of flow that can occur in a Parshall Flume : free flow and submerged flow.
• Some states specify the use of Parshall flumes, by law, for certain situations ( commonly water rights ).
• If there is submerged flow, adjustments need to be made in order for the Parshall Flume to work properly.
• These final two equations are very similar to the Q = CH a n equations that are used for Parshall Flumes.
• Illustrated above is a unitless E  Y diagram and how Energy and depth of flow changes throughout a Parshall Flume.
• The design of the Parshall flume is standardized under ASTM D1941, ISO 9826 : 1992, and JIS B7553-1993.
• Lacking the extended throat and discharge sections of the Parshall flume, Montana flumes are not intended for use under submerged conditions.
• The Parshall flume accelerates flow though a contraction of both the parallel sidewalls and a drop in the floor at the flume throat.
• The Parshall flume accelerates flow through a contraction of both the parallel sidewalls and a drop in the floor at the flume throat.
• Unlike the Parshall flume, the Cutthroat flume lacks a parallel-walled throat section and maintains a flat floor throughout the flume.
• The design of the Cutthroat flume is standardized but not covered by a national or international standard ( unlike the Parshall flume ).
• The Parshall flume is an empirically calibrated device, so interpolation between listed sizes is not an accurate way to make intermediate size flumes.
• The measurement calculations are the same as for free-flow in a standard Parshall flume, but submerged flow cannot be adjusted for.