Greyline Portaflow PT400, Руководство пользователя

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3.5 Instrument Calibration
The Portaflow is fully calibrated before it leaves the factory; however the following adjustments are provided to
allow you to further ‘fine tune’ your instrument to suit local conditions and application where necessary. Apart from
the zero flow offset adjustment, these are normally carried out only where the instrument is to be used in a
permanent or semi-permanent location.
3.5.1 Adjusting the zero cut-off
This adjustment allows you to set a minimum flow rate (m/s) below which the instrument will indicate ‘0’. The
default setting is 0.02 m/s but you may adjust this value if required.
1. With the instrument operating in FLOW READING mode, press the Options key to access the
FLOW READING OPTIONS menu shown.
2. Select Zero Cutoff (m/s) and press ENTER.
3. Enter the value for the Zero Cutoff (e.g. 0.06
m/s) then press ENTER.
4. Scroll down to select Exit and press ENTER to
return to the FLOW READING screen.
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
3.5.2 Adjusting the set zero flow offset
The Portaflow instrument operates by comparing the time taken to send an ultrasonic signal between two
transducers in either direction. A Set zero flow offset adjustment is provided to compensate for any inherent
differences between the two sensors, noise pick-up, internal pipe conditions etc. It can be used to ‘zero’ the flow
indication under no-flow conditions.
If you have adjusted the
Zero Cutoff
point to anywhere above ‘0’ you must reset it to
‘0’ before you can observe and adjust the
Set zero flow
offset, as its value is very
small. Once the
Set zero flow
offset has been calibrated you can then reapply the
Zero
Cutoff
if required.
1. Stop the liquid flow.
2. With the instrument in FLOW READING mode press the Velocity function key and observe the
reading (m/s). Any reading other than 0.000 indicates an offset error and in practice this will typically be in the
range ±0.005m/s (possibly higher on smaller diameter pipes). If a greater figure is shown it is worth
calibrating the offset to obtain a more accurate result. Continue as follows:
3. Press the Options key to access the FLOW
READING OPTION screen shown.
4. Select Set zero flow (m/s) and press ENTER.
5. Press ENTER on the subsequent screen to
accept the change, which will return you to the
screen shown.
6. Scroll down to select Exit and press ENTER to
return to the FLOW READING screen.
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