Emerson El-O-Matic E Series - L1 One-Way Stroke Limit Adjustment

Safe Failure Fraction
Section 10: Safe Failure Fraction
SFF=0 without external diagnostic tests.
SFF>0 with external diagnostic tests, carried out according to denition 3.8.7 of IEC 61508-4.
• SFF = 91% with Partial-Stroke Test.
• SFF = 99% with Full-Stroke Test.
The SFF shall be evaluated for the entire nal element sub-system.
The diagnostic test shall be performed considerably more often than the demand of the
safety function.
SIL Safety Manual
DOC.SILM.EEP.EN Rev. 0
April 2017
12
Section 10: Safe Failure Fraction