Compur Monitors Statox 506, Operation Manual

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11 Functional Safety
Here is all information you need when you have to design a safety instrumented system (SIS) with safety
integrity level 2. The user alone is responsible for the integration and the intended use of this system.
11.1 Safety Function
Statox 506 detects toxic gases in the ppm range and oxygen in % volume range. It monitors the
measured concentration also on an analog current output 0 – 22 mA:

0 mA signal system failure (3-wire operation)

2 mA signal service mode (and system failure 2-wire operation)

4 mA signal 0% of the measuring range

20 mA signal 100% of the measuring range

22 mA signal overrange
11.2 Diagnostic Time and Measuring Cycle
The maximum diagnose delay is 12 hours. Within this time interval all hardware- and sensor failures will
be detected, and the sensor head will go into a safe mode of operation.
The measuring cycle is 1 second. Within the same interval the analog output and the display are updated.
11.3 Installation and Parameter Settings
These parameter settings are mandatory in order to achieve the relevant failure rates and the SFF:

The analog output current in the service mode must be set to 2 mA. Only with this setting
measuring mode and service mode can be differentiated.

The ambiance must comply with specifications.
11.4 Maintenance Schedule
The following maintenance procedures are mandatory:

Check housing and washers. Replace if damaged, corroded or missing.

Check dust filter and sensor for pollution and damage. Replace if necessary. Check more often in
harsh ambiance.

Check plausibility of temperature reading (see chapter 6.7).

Check watchdog (see chapter 6.7).

Check sensor with gas (see chapter 6.5). Check more often if installed in harsh environment.

Replace or calibrate the sensor if the best before date has been exceeded. Depending on the
environment a frequent sensor replacement might be necessary.
11.5 Repair and Spare Parts
Repair work on hardware and housing must exclusively be done by trained and authorized personnel.
Use original parts only.