VortexMaster FSV430, FSV450 SwirlMaster FSS430, FSS450
| CI/FSV/FSS/430/450-EN Rev. G 57
6.7.3
Natural gas calculation in accordance with AGA8 /
SGERG88
For elaborate information on the configuration of the natural
gas calculation according to AGA8 / SGERG88, follow the
description in the Chapter "Commissioning“ in the operating
manual.
6.8
Zero point adjustment under operating conditions
Automatic zero point balancing
With automatic zero point balancing, the transmitter
determines the noise threshold of the sensor signal
automatically. As long as the sensor signal remains above the
determined noise threshold, this is recognized as a valid flow
signal.
Automatic zero point balancing should be rerun in the event of
the following changes:
— Change in external installation conditions, such as more or
fewer vibrations, pulsations, or electromagnetic field
interspersion.
— Replacement of the transmitter communication board.
— Replacement of the sensor or sensor electronics.
For zero point balancing, the conditions in the meter tube have
to correspond to the operating conditions for zero flow.
Automatic zero point balancing is started in the "Device Setup
/ Plant/Customized / Field optimization / Auto Zero" menu.
NOTICE
If the results of automatic zero point balancing are not
acceptable, manual zero point balancing can be performed.
Manual zero point balancing
For manual zero point balancing, the noise threshold of the
sensor signal must be determined manually. The same
requirements apply for manual zero point balancing as for
automatic zero point balancing.
1. Read out the signal amplitude of the source of
interference in the "Service / Sensor / Signal Magnitude"
menu. Note down the maximum value of the signal
amplitude.
2. Multiply the calculated maximum value by a safety factor
of between 1.2 and 2.0. Experience has shown that a
value of 1.7 yields very good results.
3. Enter the calculated value in the "Device Setup / Field
optimization / Low Flow Thld." menu.
4. Check the zero point setting in the process display / at the
current output.
5. Check whether the lowest desired lower range value can
be achieved with the new zero point setting.
NOTICE
Zero point settings > 200 indicate an elevated potential for
interference (vibrations, pulsations or EMC interference).
The installation location and installation of the device should
therefore be checked and appropriate measures taken, if
necessary, to eliminate interference.
