10
51-650 Model 961/962 Echotel SIL Safety Manual
6.0
Recurrent Function Tests
6.1
Proof Testing
6.1.1 Introduction
Following are the procedures utilized to detect Dangerous
Undetected (DU) failures.
6.1.2 Interval
To maintain the appropriate Safety Integrity Level of a
Safety Instrumented System, it is imperative that the entire
system be tested at regular time intervals (shown as TI in the
appropriate standards). The necessary time interval is deter-
mined by what is required to achieve the appropriate SIL
level for PFDavg.
NOTE: It is the responsibility of the owner/operator to select the type
of inspection and the time period for these tests.
6.1.3 Recording Results
Results of the Proof Test should be recorded for future
reference.
6.1.4 Suggested Proof Test
Suggested proof tests are provided for the relay and loop
versions of the 961/962.
