SICK EuroFID, Operating Instructions Manual

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146 EuroFID · Operating Instructions · 8011094 V2.3 · © SICK AG
Calibration
12.1
Introduction to calibration of the EuroFID
Why calibrate the device?
It is unfortunately unavoidable that the properties of pneumatic and electronic
components change slightly with time during operation of the device. These small changes
result in changes in the measured values of the precise measuring system of a gas
analyzer, even if the external conditions do not change.
To compensate for this effect, the gas analyzer must be regularly calibrated. During
calibration the measuring efficiency of the gas analyzer is tested with calibration gases,
and the determined deviations from the set conditions are compensated by internal
adjustment of the measuring system.
The main parameters of the measuring system are
– Zero point (determined by the measuring behavior if there is or should be no cause for
the measuring effect)
– Sensitivity (determines the ratio between the cause of the measuring effect and the
displayed measurement result).
Both parameters are calibrated: With “zero gas” and “span gas” ( → P. 147, §12.3 ).
How is calibration performed on the EuroFID?
a) Calibration gas with an exactly defined setpoint value (= concentration of the substance
to be measured) is supplied to the analyzer unit.
b) The EuroFID determines the measured value (actual value) of this calibration gas.
c) The EuroFID compares the actual value with the setpoint value, calculates the deviation
and then corrects the internal calculation parameters.
When is calibration necessary?
The EuroFID should be calibrated
●
After start-up
●
At regular intervals during operation (approx. weekly).
12.2
Types of calibration
The EuroFID offers several options for calibration:
●
Manual calibration: The calibration procedure is started with a menu function and the
process is monitored ( → P. 151, §12.5 ). Calibration is only valid if you confirm the
displayed result.
●
Automatic calibrations: The EuroFID controls the calibration procedure itself. The
calibration results are automatically valid.
The following settings must be modified for automatic calibration:
– Calibration control (
→ P. 148, §12.4.1 )
– Setpoint value for span gas ( → P. 149, §12.4.2 )
The span gas should also be available. Recommendation: Install a pressure monitor on
the span gas supply and connect the signal of the pressure monitor with the “Gas
supply malfunction” signal input (
→ P. 61, §6.3.2 ).
●
Starting automatic calibration: There are two options for starting automatic calibration:
– The EuroFID starts automatic calibration at regular intervals itself. The calibration
times must be programmed accordingly ( → P. 150, §12.4.3 ).
– Start calibration with the “Calibration block” control input ( → P. 65, §6.3.6 ).