Micronics portaflow 220, User Manual

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3: Operating Procedures
20
Portaflow 220 User Manual
(Issue 1.0)
3.5.3 Adjusting the calibration factor
With the system running:
1. Stop (
Stall
) the Portaflow’s totaliser facility and zero it ( Paragraph 3.6.1 ).
2.
Run
the Portaflow’s totaliser to measure the total flow over a 30-60 minute period, and note the total flow
indicated by the reference flow meter over the same period.
3. Calculate the % error between the Portaflow and reference meters. If the error is greater than ±1%
calibrate the Portaflow as detailed below.
3.5.4 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:
Key Point: In order to cancel any applied offset you must either read the flow via
Quick Start
or switch the Portaflow instrument OFF & ON. Any value that you trim-
out using the offset adjustment will be added/subtracted from the flow reading
across the whole range.
Key Point: USE THIS FACILITY WITH CARE & ONLY WHERE NECESSARY
The Portaflow instrument is fully calibrated before leaving the factory and under nor-
mal circumstances does not require further calibration when used on site.
This facility can be used to correct the flow indication where unavoidable errors occur
due to the lack of a straight pipe or where the sensors are forced to be fitted close to
the pipe-end, valve, junction etc.
Any adjustment must be made using a reference flowmeter fitted in the system.
4. Press the
Options
key to access the
FLOW
READING OPTION
screen shown.
5. Scroll down and select
Calibration
factor
.
6. Change the calibration factor according to
the error calculated in step 3. For example, if
the Portaflow was reading 1% high then
increase the
Calibration factor
value
by 0.010. Conversely, if the reading is 1%
low then decrease the calibration factor to
0.990.
7. Press
Enter
to apply the change.
8. Select
Roughness factor
or
Exit
as
required.
FLOW READING OPTION DD-MM-YY HH:MM:SS
Data review
Zero Cutoff (m/s) : 0.00
Set zero flow (m/s) : 0.00
Damping (secs) : 10
Totaliser : Run
Reset +Total
Reset –Total
Calibration factor : 1.000
Roughness factor : 0.01
Diagnostics
Exit
Pipe Material Roughness Factor
Non ferrous metal
Glass
Plastics
Light metal 0.01