Micronics Portaflow 222, Руководство пользователя

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Micronics Portaflow 222 & 333 User Manual
Issue 3.1 Feb 20 Page 27
4.6 Changing calibration parameters
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.
4.6.1 Adjusting the zero cutoff
This adjustment allows you to set a minimum flow rate (m/s) below which the instrument will indicate
‘0’. The default setting is 0.1 m/s but you may adjust this value if required.
1. Select View / Edit Site Data from the MAIN MENU.
2. Use the UP/DOWN arrow keys to select Cutoff Velocity . Press the ENTER key.
3. Edit the value as required and then press the ENTER key.
4. Scroll down to select Exit and press the ENTER key to return to the View/Edit Site Data menu.
4.6.2 Adjusting the zero flow offset
The Portaflow unit operates by comparing the time taken to send an ultrasonic signal between two
transducers in either direction. A 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’ BEFO
RE 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 ENTER key and select ‘Yes’ to confirm that you want to exit the flow screen. The
Main Menu is displayed.
4. Select View / Edit Site Data .
5. Use the UP/DOWN arrow keys to select Cutoff Velocity . Press the ENTER key.
6. Edit the value as required and then press the ENTER key.
7. Scroll down to select Exit and press the ENTER key to return to the View/Edit Site Data menu.
8. Scroll down to select Read flow using selected sensor and press the ENTER key.
9. Check that the the Portaflow is now reading zero correctly.
10. Restart the fluid flow.