Manual

64
SP4000 Flow Computer
FLOW INPUT
6.8
FLOW INPUT
(Continued)
The flow computer will then compute the gas expansion factor
(ε
1
), (Y
1
) using one of the following equation:
Orifice Case:
V-Cone, Venturi, Flow Nozzle, Wedge Case:
Y
1
=
Annubar, Pitot, Target Case;
Y
1
=
ε
1
Gas expansion factor
β BETA (geometric ratio)
∆p Differential pressure
κ Isentropic exponent
p
1
Inlet pressure (absolute)
DP FACTOR
(Continued)
∆p
27.7 • p
1
R=1–
κ−1
1−β
4
) •(
κ
• R
2/
κ
• (1 - R
(κ−1)/κ
)
[(1 −(β
•
4
R))• (1 - R)]
2/
κ
ε
1
=
ε
1
= 1.0
NOTE: 27.7 is a units conversion constant from the absolute inlet
pressure units to the differential pressure units. (27.7 is for
psia to "H2O, use other units conversions as required.).
∆p
κ • p
1
• 27.7
ε
1
=1– (0.41 + 0.35 β
4
) •
[]
Y =
1