Dwyer UFC - Manual (Page 29)

3: Operating Procedures
25
3.3.4 Adjusting the roughness factor
The roughness factor compensates for the condition of the internal pipe wall, as a rough surface will cause
turbulence and affects the flow profile of the liquid. In most situations it is not possible to inspect the pipe
internally and the true condition is not known. In these circumstances experience has shown that the following
values can be used:
The increase in the roughness factor has the effect of reducing the measured flow rate, compensating for the
drag caused by the rougher internal surface.
With the system running in FLOW READING mode:
1. Press the Options key to access the FLOW
READING OPTION screen shown.
2. Scroll down and select Roughness factor
then press ENTER.
3. Change the roughness factor according to the
pipe material and condition as described above.
4. Press ENTER to apply the change.
3.3.5 Adjusting the damping factor
By averaging-out the flow rate over several seconds, the Damping factor can be used to smooth out rapid
changes in flow rate to prevent wild fluctuations in the displayed flow value. It has a range of 1 to 50 seconds, with
a default setting of 10. With the system running in
FLOW READING mode:
Pipe Material Roughness
Factor
Pipe Material Roughness
Factor
Non ferrous metal
• Glass
• Plastics
• Light metal
0.01 Welded steel pipes, new:
• Long usage, cleaned
• Lightly and evenly rusted
• Heavily encrusted
0.1
Drawn steel pipes:
• Fine planed, polished
surface.
• Plane surface
• Rough planed surface
0.01 Cast iron pipes:
• Bitumen lining
• New, without lining
• Rusted / Encrusted
1.0
FLOW READING OPTION DD-MM-YY HH:MM:SS
Data review
Zero Cutoff (m/s) : 0.010
Set zero flow (m/s) : 0.000
Damping (secs) : 10
Totalizer : Run
Reset +Total
Reset –Total
Calibration factor : 1.000
Roughness factor : 0.010
Alarm Settings :
Max Pulse Freq (Hz) : 10.00
Flow at Max Frequency : 200.00
Calculated Pulse Value: 2.00
Diagnostics
Select Totals : +Total
Exit