Yokogawa digitalYEWFLO (DY) - Manual (Page 60)

MAINTENANCE
IM 1F2B4-01-YIA
Page 64
4.1.6 Increasing gas and steam flow measurement accuracy by correcting for gas expansion
To achieve the highest level of performance from a vortex meter when measuring a compressible fluid,
YEWFLO offers a gas expansion factor which will automatically make the necessary correction and
improve gas accuracy to ±0.8% of rate over the full operating range. Without the gas expansion factor, the
standard accuracy is 1.5% of rate.
The pressure drop across the shedder bar increases with increasing flowrate. As the pressure drop
increases, the gas expands. Gas expansion due to the higher pressure drop will cause the vortex flowmeter
to read high. To compensate for this velocity activate the D06: EXPANSION FA parameter. To activate this
function, please follow the steps below:
NOTE: Do not activate this function for liquid flow applications. Review the setting of parameter B04:
FLUID to confirm the settings are for Gas or Steam only.
BT200 handheld terminal BT100 handheld terminal
D :ADJUST Proceed to the menu screen
and select the D: ADJUST and
press ENTER. Press the MENU key to move
to the D: Adjust menu.
D06 :EXPANSION FA
ACTIVE Scroll through the parameters
to D06 :EXPANSION FA and press
ENTER. Using the PRMTR key
move to parameter D06
:Expansion FA.
Using the arrow keys, select
ACTIVE and press ENTER
twice. Then, press F4, OK. To activate this feature use the
INC or DEC key to select
active and press ENT twice.