68
Flow-condition pressure and temperature
Section 5: Calibrate and configure the meter
3410 Series Gas Ultrasonic Meters Operations Manual
January 2018
3-9000-777 Rev E
Data updates
The Daniel 3410 Series Gas Ultrasonic Flow Meter samples the input analog signal(s) and
updates the corresponding data point(s) (
LiveFlowPressure
,
LiveFlowTemperature
) once per
second
regardless of the input selection
(disabled, live, or fixed).
Every five seconds, the meter updates the “in-use” flow-condition pressure and temperature
values (
FlowPressure
,
AbsFlowPressure
,
FlowTemperature
) depending upon the input selection,
validity of the input data, and the selected data source upon alarm according to
Table 5-7
.
The flow-condition absolute flow pressure is calculated as shown in
Equation 5-6
.
Equation 5-6 Flow-Condition Absolute Pressure
where
Table 5-7 Flow-condition pressure and temperature data source
Input Type
(EnablePressureInput
or
EnableTemperatureInput)
Data Validity
(
PressureValidity
or
Tem-
peratureValidity
)
Data Source Upon Alarm
(
FlowPOrTSrcUponAlarm
)
“In-Use” Data Source
(
FlowPressure
or
FlowTem-
perature
)
Disabled
N/A
N/A
“In-Use” value unchanged
Live
Valid
N/A
Average of live values
(
LiveFlowPressure
or
Live-
FlowTemperature
)
Invalid*
Last good value
“In-Use” value unchanged
Fixed
Fixed data point
(SpecFlowPressure
or
Spec-
FlowTemperature)
Fixed
Valid
N/A
Fixed data point
(SpecFlowPressure
or
Spec-
FlowTemperature)
Invalid
Last good value
“In-Use” value unchanged
Fixed
Fixed data point
(SpecFlowPressure
or
Spec-
FlowTemperature)
*Live input can be invalid due to (a) one or more live values is/are at or outside the alarm limits, or (b) the input is being cali-
brated.
=
flow-condition absolute pressure (MPaa) (
AbsFlowPressure
)
=
flow-condition pressure (MPa if
InputPressureUnit
=FALSE,
MPaa if
InputPressureUnit
=TRUE) (
FlowPressure
)
=
(specified) atmospheric pressure (MPaa) (
AtmosphericPress
)
Pabs f
,
Pf PAtmosphere
+
=
InputPressureUnit
FALSE Gage
(
)
=
Pabs f
,
Pf
=
InputPressureUnit
TRUE Absolute
(
)
=
P
abs f
,
P
f
P
Atmosphere