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Model 3095MV™
Why Fully Compensated DP Flow?
| Traditionally,
DP flow has been calculated in a DCS or flow computer using a simplified mass flow
equation. In simplified DP mass flow measurements, a constant is used to represent many of
the terms in the flow calculation: |
Compensating
flow is the process of combining the dynamic fluid condition values with the flow signal
to calculate true flow. The Model 3095MV uses a fully compensated equation from mass flow
through any differential producer: |
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constant combines unit conversion factor, velocity of approach factor, gas expansion
factor, and discharge coefficient.
In fact, only the units conversion factor
is constant. The other terms (discharge coefficient, velocity of approach factor, and gas
expansion factor) are functions of the process variables. The simplified flow equation
cannot compensate for changes in these terms, resulting in unrecorded errors in the
calculated flow rate. |
N =
units conversion factor
Cd = discharge coefficient
E = velocity of approach factor
Y1 = gas expansion factor
d2 = bore of differential producer
p = densityThe Model 3095MV
provides the greatest DP flow accuracy over the widest operating range by dynamically
calculating all flow equation coefficients real time, including discharge coefficients,
velocity of approach factor, thermal expansion effects, and density. This fully
compensated flow equation reduces the sources of traditional DP flow uncertainty, thereby
providing a more accurate flow calculation. |
How Does the 3095MV
Calculate Mass Flow?
Using the EA Software the
user enters the process fluid (EA database already knows molecular weight, isentropic
exponent, and constants), primary element type and size, and pressure and temperature
operating conditions.
The Model 3095MV measures the static pressure, differential pressure, and
process temperature.
The internal flow computer dynamically calculates all flow equation
coefficients in real time including: discharge coefficient, velocity of approach factor,
thermal expansion effects, and density
Result is the Model 3095MV provides the greatest DP flow accuracy over the
widest operating range!
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Emerson Process Management,
Rosemount Division, 8200 Market Blvd.
Chanhassen, MN USA 55317
North America: 1-800-999-9307 International:
952-906-8888 Fax: 952-949-7001
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