From Birgir Tómas Arnar a civil engineer working in Reykjavik, Iceland.
"A FL16 water flow logger installed in a manhole
with no need of confined space entry, connected to a 12 inch concrete sewer influent pipe. We calibrated the monitor by
measuring the velocity in the pipe with Global Water´s FP211 flowprobe and
matched this velocity to the value computed by the Manning´s equation in the software, because the slope of the pipe is difficult
to obtain from measurements due to settling and taking the roughness coefficient "n" from tables is no more than a
guestimate. This approach should give good results. This is part of a I/I study."