Dwyer UFC User Manual download pdf (Page 29)

3: Operating Procedures

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

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Dwyer UFC User Manual Page 29

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