Xylem FL16 WATER FLOW LOGGERS - Manual (Page 33)

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XIX. Calculations:
Manning’s equation:
Velocity = (1.486 / n) * (WA / WP) ^ 0.6667 * (Slope) ^ 0.5
Flow = (1.486 / n) * (WA) * (WA / WP) ^ 0.6667 * (Slope) ^ 0.5
Where n = Manning’s Roughness Number
WA = Wetted Area in square feet, based in measured level
WP = Wetted Perimeter in feet, based in measured level
Slope = Pipe Slope in decimal form
Velocity is in feet per second
Flow is calculated in cubic feet per second
Flumes and Weirs:
Most of the stored flumes and weirs have equations in the form of:
Flow = C * (H+A)^B
Where
A is a level offset number, generally zero
B is an exponent
C is a multiplier
H is the measured water level in feet
Flow is calculated in cubic feet per second
Flumes and weirs not appearing in the pull-down lists can be added by modifying the
flumes.lst and weirs.lst files. These are text files stored in the folder containing the
FL16 Flow software and can be edited in a text editor. The format of these files is
described in the header at the top of each one. Adding flumes or weirs to the list
consists of specifying the name as it will appear in the menu as well as the
coefficients in the equation listed above or a file name for the lookup table that will be
used to correlate flow to level. Note that if the logger is programmed to use a flume
or weir that has been added to this list, an error message will appear when the
logger is connected to a computer which does not have the correct flumes or weirs
.lst file.