Ag7 - Aga 7 Measurement Of Gas By Turbine Meters - Siemens Moore 353 User Manual

UM353-1

3.2.5 AG7 - AGA 7 Measurement of Gas by Turbine Meters

AG7 function blocks, which can be used on a one per loop
basis, are available in firmware 1.30 and higher, This block
uses the AGA 7 (American Gas Association Report #7)
calculation to accurately measure the volume flow of gas at
base conditions using a turbine meter. The basic equations
calculated by this block in accordance with AGA Turbine
Meter Report No. 7, 1985 (AGA Catalog No. XQ0585) are:
Q = Q (T /T )(P /P )(Z /Z
b f b f f b b
Q
where: = volume flow at standard conditions
f
Q
= volume flow rate at base conditions
b
P
= flowing pressure (psia)
f
T
= flowing temperature)
f
Z
= compressibility at flowing conditions
f
P
= base pressure (psia)
b
T
= base temperature (°F)
b
Z
= compressibility at base conditions
b
Block output Q b is updated continuously and is the volume flow rate at base conditions in the same units as input
Q f . T b and T f are converted within the block from °F to °R (adds 459.67 to the °F input value) for the actual
calculation. Compressibility factors (
and downloaded from a host device, or calculated in the controller using the AG8 (AGA 8 Compressibility Factors
of Natural Gas) function block.
March 2003
)
f
Z , Z
) can be entered manually using HLD (Hold) function blocks, computed
f b
P
Q
f
AGA 7
Z
f,b
Application Diagram
AGA 7
AG7
Input Qf Qf
AGA 7
Pf
Input Pf
Input Tf Tf
Zf
Input Zf
Input Zb Zb
P b
base Pressure (psia)
T b
base Temperature (deg F)
I N P U T Q f
INPUT Qf ..............
I N P U T P f
INPUT Pf ..............
I N P U T T f
INPUT Tf ..............
I N P U T Z f
INPUT Zf ..............
I N P U T Z b
INPUT Zb .............
E S N
Exec. Seq. No. ..................... 000 to 250 (000)
T
f
f
Q
b
Function Blocks
ESN = 000
Qb
Output Qb
(14.73)
.............................. Real
(60.0)
................... Real
loop tag.block tag.output (null)
loop tag.block tag.output (null)
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