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 by means of a ramp that both rises from the floor of the flume and contracts on the sides (usually).
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.
Openchannelflow Palmer-Bowlus Flumes utilize the trapezoidal design (second from the top) to provide lower flow sensitivity while still proving a somewhat wide 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-Bowlus Flumes:
PALMER-BOWLUS FLUME VARIATIONS
- Permanent Style with Integral Approach
- Permanent Style without Approach
- Insert Style
- Cutback (Insert) Style
- Permanent Style with Approach
- Most common
- Point of measurement: inside the flume
- Length: 4D+1-inch
- Approach: full length, integral to the 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.)
- Permanent 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 exists, the standard is for the general class of Palmer-Bowlus Flumes, not a specific design. Individual design is proprietary from manufacturer to manufacturer.
The result is that a Palmer-Bowlus 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