FLOWSIC100 Operating Instructions
Gas Velocity Monitor
Product Description
40 © SICK MAIHAK GmbH · Germany · All rights reserved 8012513/03-2008
Calculating the volumetric flow under standard conditions
The volumetric flow can be converted to the normalized state as follows:
Q
ac
:Volumetric flow under actual conditions
Q
sc
:Volumetric flow under standard conditions
F: Humidity in percentage volume; usually configured as an installation-specific
substitute value.
If an optional analog module is used as an analog input for connecting a
separate humidity monitor, the volumetric flow can be normalized with the
current installation values.
p_Duct: Absolute pressure in the duct; usually configured as an installation-specific
fixed/substitute value.
If an optional analog module is used as an analog input for connecting a
separate pressure sensor, the volumetric flow can be normalized with the
current installation values.
p_normal: 1013 mbar
T_Duct: Duct temperature (in K): in the FLOWSIC100, you can select whether a
permanent substitute temperature calculated with the ultrasound
measurement, or read via the optional analog input (for greater accuracy) is
used.
T_normal: Normalized temperature. In Europe 273 K, in USA 293 K
2.4.2 Calibrating the Temperature
The temperature measurement must be calibrated for calculating the flue-gas temperature
accurately with the FLOWSIC100. There are only two cases where this calibration is not
necessary:
• The exact sound velocity in the flue gas under normalized conditions is known
(1013 mbar, 0 °C), as is the case with air, for example, (331 m/s)
• The exact active measuring distance is known.
The calibration is carried out by means of a comparison measurement using a separate
temperature sensor (for example, Pt100) with at least 2 different temperatures (see
Section 4.3.3 for calculating and entering the coefficients).
Q
sc
Q
ac
100 F–
100
-------------------
⎝⎠
⎛⎞
p_Duct T_normal⋅
p_normal T_Duct⋅
---------------------------------------------- -
⎝⎠
⎛⎞
⋅⋅=
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