For example, if the average flow rate is 100 gpm and the
Hysteresis
is set to 10%, a filter window of 90…110 gpm is
established Successive flow measurements that reside within that window are recorded and averaged in accordance with the
Damping
setting Flow readings outside of the window are rejected or accepted in accordance with the
Bad Data Rejection
setting
Filter settings for this example:
Filter Method
Adaptive
Damping
40 seconds
Sensitivity
60%
Hysteresis
10%
Bad Data Rejection
3
Flow Within
Hysteresis Limit
±10% Hysteresis
Limit
Flow
150
100
50
0
110
90
Figure 27: Hysteresis window
Bad Data Rejection (Range 0…10 Samples; Default: 3)
The
Bad Data Rejection
setting is related to the number of successive
readings
that must be measured outside of a the
Hysteresis
value before the flow meter considers the new flow value valid In this example, a
Hysteresis
setting of 10% produces
a ± 10% band centered on the current valid flow rate of 100 gpm
The
Bad Data Rejection
setting is the number of successive
samples
that must be outside of the
Hysteresis
window before
the flow meter considers the change in flow as real Larger values are entered into the
Bad Data Rejection
window when
measuring liquids that contain gas bubbles, as the gas bubbles tend to disturb the ultrasonic signals and cause more
extraneous flow readings to occur Larger
Bad Data Rejection
values tend to make the flow meter less responsive to rapid
changes in actual flow rate
In
,
flow data falls outside the flow
Hysteresis
window but does not reach the minimum time specified in
the
Bad Data Rejection
window When data appears that is outside the
Hysteresis
band and shorter than the
Bad Data Rejection
window time, the data is rejected
Parameter Descriptions by Menu
Page 22
May 2021
TTM-UM-02537-EN-06