European Safety Systems Ltd.
Impress House, Mansell Road, Acton, London W3 7QH
sales@e2s.com Tel: +44 (0)208 743 8880
Document D150-00-151-IS Issue 5 26-08-2020
Sheet 3 of 3
www.e2s.com Fax +44 (0)208 740 4200
9)
SIL 2 Reliability Data
Reliability and Functional safety IEC/EN61508
which has been assessed and is considered
suitable for use in low demand safety function:
• Random Hardware Failures and Systematic
Failures (route 2H)
• As an unvoted item (i.e. hardware fault tolerance
of 0) at SIL 2
The product was assessed against failure modes:
• Failure to close a contact when the call point is
struck with specified force
• Failure to open a contact when the call point is
struck with specified force
• Spurious output despite no input
Integrity in respect of failure to
close
SIL 2
Total Failure rate
0.133 pmh
“hazardous” failure rate (revealed)
0 pmh
“hazardous” failure rate
(unrevealed)
0.1 pmh
“safe” f
ailure rate (revealed)
0.033 pmh
“safe” failure rate (unrevealed)
0
Diagnostic Coverage
99%
System type
A
Hardware Fault Tolerance
0
Safe Failure Fraction
>99%
PFD (hazardous failure)
1.25 x 10
-3
Proof Test Interval
Up to 1 year
