Emerson Daniel 3415

This feature is enabled via the AGA10 Key (see Section 3.1.3). The gas property data
required for using this feature can be specified via data points or optionally read from a
Daniel GC (Section 5.10). The AGA8 Detailed Method must be selected (via the
HCH_Method data point, Section 5.10) in order for the AGA10 calculations to be
performed (as the AGA10 calculations require AGA8 Detailed method calculation
intermediate results).
Every five seconds the meter updates the AGA10-calculated sound velocity. This value is
readable via the AGA10SndVel data point and the calculation status value is readable via
the AGA10SndVelStatus data point. The status values are as listed in the table below:
AGA10 calculation statusTable 4-2:
AGA10SndVelStatus value Description
0 Calculation OK (no errors)
1 Calculation not performed as the feature is not enabled (see .
AGA10SnVel is set to zero.
2 Calculation not performed as the selected AGA8 method is not
the Detailed method (HCH_Method not set to Detailed Method
(3)). AGA10SnVel is set to zero.
3 Calculation not performed due to invalid AGA8 calculation re-
sults. AGA10SndVel is set to zero.
4 Calculation error due to division by zero. AGA10SndVel is set to
zero.
Over the course of an hour (starting from the top of the hour), the meter calculates the
average measured sound velocity (the average of the average weighted sound velocity)
and the average AGA10-calculated sound velocity. At the end of the hour, the two
averages are compared; the comparison error (%) is readable via the SndVelCompErr data
point.
Note that the comparison error is only calculated at the end of the hour if during the hour
all of the following are true:
• No AGA10 sound velocity calculation errors occurred (i.e., AGA10SndVelStatus
always equal to 0),
• the measured flow velocity was always above the minimum sound-speed-check flow
velocity (specified via the SndSpdChkMinVel data point which has a default value of
1 m/ s), and
• the measured sound velocity was always valid (as indicated by the QMeterValidity
data point).
4.4.3
Average weighted gas flow velocity
When all active chords are non-failed, the average weighted gas flow velocity is a weighted
sum of the chord velocity measurements as shown in Equation 4-6 where the chord
weights are determined by the meter geometry.
Measurement
Operations manual 23