Emerson Daniel 3410 Series Operation Manual page 30

Measurement
January 2019
Table 4-2: AGA10 calculation status
AGA10SndVelStatus value
2
3
4
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
weights are determined by the meter geometry.
Equation 4-4: Average weighted gas flow velocity
where
V
AvgWtd
Wtd
V
chord
4.4.4 Average weighted flow velocity using chord proportions
In the event of one or more chord failure(s), the meter operation is dependent upon the
number of non-failed chords. If there is at least one operating chord, then the meter uses a
velocity estimation method described in the following paragraphs.
30
Description
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.
Calculation not performed due to invalid AGA8 calculation
results. AGA10SndVel is set to zero.
Calculation error due to division by zero. AGA10SndVel is set to
zero.
V
AvgWtd
= average weighted gas flow velocity (m/s) (AvgWtdFlowVel)
= chord weight (dimensionless) (WtA ... WtH)
chord
= chord average gas velocity (m/s) (FlowVelA ... FlowVelH)
(continued)
Equation 4-4
= ∑ Wt V
ActiveCℎords cℎord
Operations manual
DAN-20057316
where the chord
cℎord
Operations manual