<5. Functions>
57
IM 01E21A02-03EN
NOTE
Pay attention to the following points when setting the flow rate span.
• For a line with a significant flow rate change, set the flow rate span to the maximum flow rate.
If the flow rate exceeds the flow rate span, the error of the flow rate% increases.
• For a line with a stable flow rate, set the flow rate span to approximately 1.5 to 2.0 times the
normal flow rate.
• Set the flow rate for which the flow velocity is comparable to the range from 0.3 to 10 m/s.
Check the flow velocity using the sizing data described in the general specifications. If the
flow velocity is checked using the parameter, it displays the value obtained by converting the
specified flow rate span to the flow velocity.
NOTE
Be sure to set the flow rate unit first when the flow rate unit and its span value are changed at the
same time.
5.1.6 Damping Time Constant Setting
The flow rate-related process value (flow velocity, volumetric flow rate, mass flow rate and
calorie), the damping time constant for flow noise (63.2% response) and the damping time
constant for AIFB output can be specified. To reduce an output fluctuation or change the
response speed, change the damping time constant (default value, 3.0 seconds).
For a piston pump, etc., the pulsing flow of up to 1 Hz can be measured with an output damping
of 0.1 seconds.
The setting can be configured with the following parameters.
Flow rate-related process values/frequency
Menu path
Display
Device setup ► Detailed setup ► Pro var ► (see below)
F
OUNDATION
Fieldbus
Device Configuration ► STB ► Device Configuration ► Configuration ► Process
Variables ► (see below)
Block
Name
Relative
Index
Parameter
Description
Display
F
OUNDATION
Fieldbus
STB
39
Velocity ► Damp AO/F
Velocity ► Velocity Damping
Specifies the damping
time constant of the flow
velocity value/frequency
output.
STB
31
Volume ► Damp AO/F
Volume Flow ► Volume Flow
Damping
Specifies the damping
time constant of the
volumetric flow rate
value/frequency output.
STB
35
Mass ► Damp AO/F
Mass Flow ► Mass Flow
Damping
Specifies the damping
time constant of the
mass flow rate value/
frequency output.
STB
43
Calorie ► Damp AO/F
Calorie ► Calorific Damping
Specifies the damping
time constant of the
calorie value/frequency
output (only available
for AXG, not for AXW).