Siemens AG
SIL Safety Manual CALOMAT 6 Gas Analyzers 12
A5E00729184-02, 07/2010
Checking safety
You should regularly check the safety function of the entire safety circuit in line
with IEC 61508/61511.
The testing intervals are determined during circulation of each individual safety
circuit in a system (PFD
AVG). Recommended prove interval depends on application
but max within one year. We recommend a prove test interval of once per moth.
To detect dangerous undetected faults the CALOMAT 6 analog output shall be
checked with following test:
To execute the safety proof test both tests (1 and 2) must be performed.
Proof test 1 consists of the steps described in table 3-1.
Step Action
1 Bypass the safety PLC or take other appropriate action to avoid a false
trip
2 Generate or simulate an alarm condition to force the Gas Analyzer
CALOMAT 6 to go to the high alarm current output and verify that the
analog current reaches that value.
3 Generate or simulate an alarm condition to force the Gas Analyzer
CALOMAT 6 to go to the low alarm current output and verify that the
analog current reaches that value.
4 Restore the loop to full operation
5 Remove the bypass from the safety PLC or otherwise restore normal
operation
Table 3-1 Steps for Proof Test 1
Proof test 2 consists of the steps described in Table 3-2.
Step Action
1 Bypass the safety PLC or take other appropriate action to avoid a false
trip
2 Perform Proof Test 1
3 Perform a two-point calibration of the Gas Analyzer CALOMAT 6
4 Perform a reference measuring with at least one measuring point
between min and max concentration. You must use a calibration gas
with a well known gas concentration. The expected result must have a
tolerance of not more than 5 %.
5 Restore the loop to full operation
6 Remove the bypass from the safety PLC or otherwise restore normal
operation
Table 3-2 Steps for Proof Test 2
This test will detect more than 90% of possible "du" failures in the Gas Analyzer
CALOMAT 6.
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