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FLOWSIC100 Flare · Operating Instructions · 8013344/11L2/V 2-5/2018-10 · © SICK Engineering GmbH
Product Description
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2.3.2
Mass flow and molecular weight determination
The mass flow of the gas is computed from flow speed and sound velocity, pressure and
further measured variables.
The molecular weight of the gas is computed from sound velocity and further measured
variables.
The operating software uses three different algorithms to calculate mass flow and
molecular weight:
a) Basic algorithm:
Uses a constant value for substance-dependent coefficient
κ
(adiabatic coefficient)
.
b) Hydrocarbon algorithm:
Determines
κ
according to the function relation to the standard sound velocity.
Standard algorithm of FLOWSIC100 Flare for flaregas applications.
c) Algorithm MR-113:
Determines
κ
under consideration of the actual gas composition for hydrocarbon mix-
ture.
2.3.3
Necessity for using external pressure and temperature transmitters
The following table shows what calculations require use of external pressure and
temperature transmitters.
General requirements
●
Temperature transmitter:
Pt100, 3- or 4-wires connection, head mounted transmitter, 2-wires Smart transmitter,
explosion protected, output 4 ... 20 mA
●
Pressure transmitter:
Absolute pressure type, 1 ... 16 bar, 2-wires Smart transmitter, explosion protected, out-
put 4 ... 20 mA
Calculation of
External pressure transmitter
External temperature transmitter
Volume flow in
standard state
x
x
Mass flow
x
x
Molecular weight
—
x
