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Local Fuel plc - Shoreham Oil Terminal
Safety Instrument System Functional Safety Assessment Stage 5
P & I Design Ltd
DOCUMENT NO: LF364100_RPT
2 Reed Street, Thornaby, UK, TS17 7AF
ISSUE: B DATE: 07.06.2016
Tel: + 44 (0)1642 617444
PAGE 21 OF 51
Fax: + 44 (0)1642 616447
www.pidesign.co.ukFinal Element:
The PILZ safety relay provides normally open volt free contacts. A 24V dc supply originating
in the Rotork actuator is fed through these contacts and back to the hardwired ESD circuit
contained with the actuator. The actuator is capable of being operated remotely, however,
without the 24V dc input to the ESD circuit the actually will fail closed.
It is certified to BS EN 61508 by SIRA for use in a SIL 2 SIS with HFT = 0. As it has fairly
recently being certified it also has a Systematic Capability assessment with a resulting SC3.
REVISION B OF FSA ACTUAL DEVICE SI-2Q REVISED DATA.
REVISION A - The value used for the actuator in LF364006_RPT utilises the average value
from the certified data. This FSA checked what the overall pfd of the SIS would be if the
worst case value was used, this changed the PFD
SYS
form 3.57x10
-3
to 3.94x10
-3
which is still
within the required 5.00x10
-3
required from the LOPA.
REVISION B - The value used for the actuator in LF364006_RPT_Revision B utilises the
worst config value 1.17x10
-3
value from the certified data. Resulting in a PFD
SYS
form
3.93x10
-3
which is still within the required 5.00x10
-3
required from the LOPA.