H, HS and HL Flumes

H flumes are well known by soil and agricultural agencies that have used them to monitor field runoff and study water shed drainage. For the past 20 years Plasti-Fab H flumes have been successfully used in the sanitary field to measure storm water, effluent and sewage streams having very broad flow ranges that otherwise would be difficult or impossible to measure in other types of flumes. Download the brochure

Unique Design

The H flumes and related HS & HL flumes are gaining in popularity due to their ability to handle wide ranging flows that can vary by as much 100:1 or more from low to peak. Because of the unique throat, which resembles a weir in some respects, the H flumes provide excellent resolution at low flows and still have capacity to capture peak flow readings on many 15 to 25 year storm events.

Flow Characteristics:

H flumes have a flat floor that must be installed level with the approach section or entrance channel. Flow must be able to free fall or spill from the end of the flume in an unimpeded manner. H Flumes are more tolerant of slope and velocity than any other style of flume. Complete flow charts for each size flume exist, but simplified flow equations are not readily available. The wall height and configuration of the throat denote flume size. HS Flumes have a more restrictive outlet orifice to increase low flow resolution, and are used on small flow streams. H flumes cover the mid-range up to about 53 MGD. The HL flume spreads the throat opening slightly and can measure flows as high as 74 MGD. The H flumes will normally be preceded by a rectangular approach channel that is approximately the same width and depth as the flume, and a minimum of 3-5 times the flume height. Approach sections are available from Plasti-Fab, and these can be adapted for connection to a pipe.

Problem Solving Adaptations:

• Permanent installation in rectangular concrete or natural channels
• Free standing flume and approach section with end adapter for connection to an upstream pipe
• Connection to downstream pipeline using an outlet drop box
• Installation in culverts and large diameter outfalls using special bulkheads and mounting hardware
• Packaged Metering Manholes for below grade installation – up to 2.0 H flume
• Wing walls for wall mounting in large quiescent basins
• Tranquilizer racks to reduce excessive velocity and turbulence problems
• FRP grating

Accessories and Instrument Setup:

• Adjustable stainless steel support brackets for all types of ultrasonic transducers
• Molded side cavities and floor cavities for:
  • Stainless steel bubble pipes
  • Stainless steel sample pipes
  • Pressure transducers
  • Capacitance probes and s/s grounding plates
• Stainless steel liftout brackets for pressure and pH probes
• 2" threaded tap for remote still well
• 8" and 12" diameter attached still wells

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