Checking The Airflow Sensor Calibration - Bosch FCS-320-TM Operation Manual

FCS-320-TM Aspirating Smoke Detector
7.8

Checking the Airflow Sensor Calibration

Check the airflow sensor value with the Diagnostic Software.
Functional principle
During initialization of the connected pipe system, the device saves the measured actual value
of the airflow as a target value via the integrated airflow monitoring. This nominal value then
serves as a reference value for the additional evaluation of a possible airflow malfunction.
Depending on the airflow threshold selected (see "Adapting the airflow sensitivity" in
Section 3.3 Airflow monitoring, page 34), the current airflow value during operation can
fluctuate around this target value without triggering an airflow malfunction. Only if the
selected airflow threshold is exceeded will the airflow malfunction be reported by the device
and thus transmitted.
Checking the actual value
The tolerance range of the selected airflow threshold and the actual and target values are
represented in the diagnostic software. The limits correspond to the airflow range set.
Check the deviation of the actual value from the target value. If there is a deviation of > ±3/4
of the set threshold, you should check the pipe system carefully (see below:
Section Troubleshooting airflow malfunction).
NOTICE!
The current airflow value may deviate from the target value not only due to a malfunction of
the pipe system (break or obstruction), but also due to fluctuations in the air pressure in the
environment.
Dependent on air pressure
To ensure long-term fault-free operation of the device, the airflow sensor must be calibrated
depending on the air pressure (see Section 6.3.2 Air-Pressure-Dependent Calibration, page 77).
Only with this type of calibration do low air pressure fluctuations remain within the
monitoring window and thus in the permissible tolerance range.
CAUTION!
If the airflow change is set at less than 30%, an air-pressure-dependent calibration must be
carried out.
Independent of air pressure
If the sensor calibration is carried out independently of air pressure, fluctuations in the air
pressure can cause undesired airflow malfunctions. If the change in airflow is greater than
30%, the calibration of the airflow sensor can be carried out independently of the air
pressure; it must then be ensured that no fluctuations in air pressure can occur in the
immediate environment.
CAUTION!
If air pressure fluctuations are anticipated in the immediate environment, the airflow sensor
has to be calibrated in dependence of air pressure (see also Section 3.3 Airflow monitoring,
page 34).
Troubleshooting airflow malfunction
If the airflow calibration has been carried out depending on air pressure and the actual value
still does not lie within the tolerance range of the selected airflow threshold (airflow
malfunction displayed on the device), then a further disturbance value in addition to air
pressure or temperature fluctuation exists.
Bosch Sicherheitssysteme GmbH Operation Guide
Maintenance | en 91
F.01U.130.928 | 1.0 | 2009.11