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Palmer-Bowlus Flume Design

Designed to be inserted into existing conduits and pipes, the Palmer-Bowlus flume has a uniform U-shaped cross section.  Flow is accelerated through the flume through the use of a ramp which rises from the floor of the flume in the downstream section.  

Unlike other flumes whose shape is rigidly defined, the Palmer-Bowlus is a general class of flumes with potentially marked differences in the throat ramp design.  

Palmer-bowlus flume throat styles

Openchannelflow Palmer-Bowlus flumes utilize the trapezoidal design (second from the top) to provide lower flow sensitivity while still proving a somewhat large useful flow range.

As long throated-flumes, Palmer-Bowlus flumes can be calculated by computer analysis (versus short-throated flumes like the Parshall which are empirical devices and must be laboratory calibrated).

The point of measurement in a Palmer-Bowlus flume is located a distance D/2 upstream of the beginning of the throat ramp (where D is equal to the flume size).

Palmer-Bowlus Flume Styles

Unlike other classes of flumes, there are four distinct styles of Palmer-Bowuls flumes:

PALMER-BOWLUS FLUME VARIATIONS

  • Permanent Style with Integral Approach
  • Permanent Style without Approach
  • Insert Style
  • Cutback (Insert) Style
  • Fiberglass 4D+1-inch style Palmer-Bowlus Flume with Approach SectionPermanent Style with Approach
    • Most common
    • Point of measurement:  inside the flume
    • Length:  4D+1-inch 
    • Approach:  full length, integral to flume
    • End connections:
      • Bulkheads
      • Pipe stubs
      • Flanges
      • Caulking collars
    • Factory integration:
      • Flow / level accessories (staff gauges, bubbler tubes, etc.)
      • Flow conditioning accessories (flow straighteners, energy absorbers, etc.)
  • fiberglass 2D+2-inch Permanent Style Palmer-Bowlus Flume without Approach SectionPermanent Style Without Approach
    • Used in long, straight pipes or well defined channels
    • Used where space is at a premium
    • Point of measurement:  upstream of the flume
    • Length:  2D+2-inches (throat only)
    • Approach:  none, must be formed upstream of the flume
    • End connections (outlet only):
      • Bulkheads
      • Pipe stubs
      • Flanges
      • Caulking collars
    • No factory integration of flow or conditioning accessories
  • Insert Style
    • Flume is set into existing U-channel or half-pipe
    • Used where space is a premium
    • Point of measurement:  upstream of the flume
    • Length:  2D+2-inches (throat only)
    • Approach:  none, must be formed upstream of the flume
    • End connections:  none
    • No factory integration of flow or conditioning accessories
  • Cutback (Insert) Style
    • Least common
    • Downstream half of sidewall above the throat is notched to slide into downstream pipe
    • Flow accuracy in the upper flow range may be diminished
    • Used where space is a premium
    • Point of measurement:  upstream of the flume
    • Length:  2D+2-inches (throat only)
    • Approach:  none, must be formed upstream of the flume
    • End connections:  none
    • No factory integration of flow or conditioning accessories

When determining the length of the styles above, D = flume width / size.  

For all Palmer-Bowlus flumes, regardless of style, the point of measurement is located a distance D/2 upstream of the beginning of the throat ramp, where D is equal to the flume size.

Palmer-Bowlus Flume Dimensions

Like Cutthroat and RBC flumes, the design of the Palmer-Bowlus is dimensionless, with each flume size based upon a standard design. The dimensions for any particular size Palmer-Bowlus rely on only one dimension, D - the width of the flume. With D known, all of the other dimensions can be readily determined.

While an industry standard does exist, the standard is for the general class of Palmer-Bowlus flumes, not a specific design of them.  Individual design is proprietary from manufacturer to manufacturer.

The result of which is that a Palmer-Bowuls flume may be similar, but not identical to that of another manufacturer.  The typical difference between Palmer-Bowlus flumes of different manufacturers is the treatment of the vertical contraction of the flume sidewalls in the throat.

PALMER-BOWLUS FLUME MASTER DIMENSIONS:  4D+1" PERMANENT STYLE WITH APPROACH

PALMER-BOWLUS FLUME MASTER DIMENSIONS:  2D+2" PERMANENT STYLE WITHOUT APPROACH

PALMER-BOWLUS FLUME MASTER DIMENSIONS:  INSERT STYLE

PALMER-BOWLUS FLUME MASTER DIMENSIONS:  CUTBACK (INSERT) STYLE

 


Image:  Teledyne Flow Measurement Handbook