Emerson Daniel 3415

For example, setting Smoothing to 20% means that of the samples used for the current
update, 20% will be from previously collected samples and 80% will be from the newly
collected samples. Thus, if eight new samples are collected, then those eight samples
along with the last two previous samples would be used together for the current update
period calculations.
Meters are configured by default for Smoothing of 0% (only new samples are used for the
Current Update period).
4.3 Acquisition mode
Daniel 3410 Gas Ultrasonic Flow Meters have two modes of normal operation: Acquisition
and Measurement. The Acquisition mode is used to acquire the ultrasonic signals. This
mode is entered when power is applied to the meter.
Once the ultrasonic signals are acquired, the Measurement mode is entered and the flow
velocity is measured. The meter remains in the Measurement mode as long as at least one
chord is operational.
If while in the Measurement mode all chords fail, then the meter re-enters the Acquisition
mode. If the VelHold data point is set to a value greater than zero, then, while in the
Acquisition mode, the meter holds the average weighted flow velocity to the last good
value for up to the VelHold number of batches before setting the velocity to zero. The
VelHold default value is 0.
The Acquisition mode uses the chords' "L" dimensions (LA…LD as appropriate to the meter
type) and the specified minimum and maximum sound velocities (SSMin and SSMax)
determines the signal search range. MinHoldTime and MaxHoldTime are also used to
determine the signal search range. The meter uses the more restrictive of SSMin/
MaxHoldTime and SSMax/MinHold time.
4.3.1
Re-acquisition
When fewer than MinChord (default 1) chords are good, then the meter re-enters the
Acquisition mode. If MinChord is set to the number of active chords, the meter will
reacquire on the first time a chord is failed for a batch.
Note that failed for a batch is different from hard failed. A chord fails for a batch when Pct-
Good[A1..D2] is less than MinPctGood.
Hard fails occur after AlarmDef number of batches in a row.
If the VelHold data point is set to a value greater than zero, then, while in the Acquisition
mode, the meter holds the average weighted flow velocity to the last good value for up to
the VelHold number of batches before setting the velocity to zero. The VelHold default
value is 0.0.
Measurement
20 3410 Series Gas Ultrasonic Flow meters