Operating Instructions FLOWSIC100
Gas Velocity Monitor
Commissioning and Configuration
8012513/03-2008 © SICK MAIHAK GmbH · Germany · All rights reserved 115
4.3.4 Entering additional Variables for Measured Value Calculation and Calibration
See also Section 2.4 This Section describes parameter settings that are necessary for calibrating gas velocity
and temperature measurements, and for outputting the volumetric flow under standard
conditions. To do this, set the measuring system to “Maintenance” mode and enter the
password level 1. Then choose the type FLOWSIC100 in the menu "Device Catalog /
Available Devices" and open the "Installation parameters" submenu (see Section 4.2.1).
Entering calibration coefficients for gas velocity measurements
Enter the calibration coefficients determined with a network point measurement using a
reference system in the group "Calibration coefficients / Calibration coefficients for
velocity".
The default settings are:
Cv_0 (absolute) = 0, Cv_1 (linear) = 1, Cv_2 (square) = 0,
Calibrating temperature measurements
The precision of acoustic temperature measurements conducted with the FLOWSIC100 is
a square function of the measuring path and the speed of sound of the real gas under
normalized conditions (see Section 2.2.2). Exact acoustic temperature measurements are
only possible if the speed of sound of the real gas remains constant at a reference
temperature. Since this is seldom the case, the internal temperature calculation in the
device must be calibrated if it is to be used to normalize the volumetric flow.
Note: The speed of sound can be configured in the User Access Level ‘‘Service” (see Service
Manual). Per default it is set to 331.5 m/s.
To calibrate the measurement, determine the value pairs from separately measured gas
temperature (for example, with PT100 sensor) and display on the LCD at a minimum of two
different gas temperatures. Convert the calculated values to absolute temperatures (add
273.15 K). You can then use a regression function to calculate the coefficients (for two
pairs by linear, with more value pairs also by square regression). Enter CT_2, CT_1 and CT_0
in the “Calibration coefficients / Calibration coefficients for temperature” group.
The default settings are CT_2 = 0, CT_1 = 1, CT_0 = 0.
Example:
Measurement FLOWSIC display Measured value PT100
T in °C
T
absolute
in K
T in °C
T
absolute
in K
1 128 401 115 388
2 186 459 170 443
T
Kal
CT 1
–
T
FLOWSIC
CT 0
–
+⋅=
CT 1
–
T2
PT100
T1
PT100
–
T2
FLOWSIC
T1
FLOWSIC
–
--------------------------------------------------------------------
=
CT 0
–
1
2
---
T2
PT100
T1
PT100
CT 1
–
–+T2
FLOWSIC
T1
FLOWSIC
+()⋅()⋅=
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