European Safety Systems Ltd.
Impress House, Mansell Road, Acton, London W3 7QH
www.e2s.com Tel: +44 (0)208 743 8880
Document D154-00-155-IS Issue 8 12-09-2022
Sheet 3 of 3
Rotate the push button anticlockwise by an angle
of 55°, see guide alignment marks on the button
and cover, shown below (1). The push button
should pop back up to its original position.
Ensure that the push button has also twisted back
clockwise by 55° to its original position see guide
marks on button and cover, shown below (2). The
unit is now reset
1. On operated unit
2. Button should pop
twist push button
up and twist back to
anticlockwise 55°
original position
to reset
Resetting an operated unit is the same as resetting
a tested unit.
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” failure 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
Note: use alignment
marks circled to
indicate the push
buttons
status/position
Unit currently shown
as ‘standby
condition’
