Xylem FL16 WATER FLOW LOGGERS - Manual (Page 29)

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separate bar graphs and are both stored; along with the level, temperature and
battery voltage data in the historical record.
The information required for the Manning’s equation is:
Pipe Diameter: The inside diameter of the pipe.
The possible units of measurement are Feet, Inches,
Meters or centimeters, which are selected from the
pulldown menu to the right of the data field. Click on
the field to enter the diameter.
Slope: The slope of the pipe can be in % or decimal
form. A slope of 1.25% is entered as 1.25 when the
percent units are selected and 0.0125 in decimal.
Roughness Number: This number, commonly
referred to as the Manning’s number or “n”, is a
measure of how much friction there is between
the water flow and the inside pipe wall. While
all surfaces are different and the roughness
changes over time, a look-up table is provided
by clicking the arrow to the right of the data field.
This number is the one most commonly used to adjust the calculated flow velocity to
match empirical measurements when calibrating the FL16 to a particular pipe.
Flumes Mode:
When the Flume mode is selected, a list of pre-
programmed flume equations is available. Click
the arrow next to the display field and access
the list. If a flume is not on the list, the custom
look-up table feature of this software can be
used as described later. In this mode, the bar
graph and historical will include flow but not velocity.
Weirs Mode:
As with flumes, this mode allows access to a list of
weirs stored in the software. Click the arrow next
to the display field and access the list. The display