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Immingham East Terminal – Gasoline Overfill Protection
Safety Instrument System
P & I Design Ltd
DOCUMENT NO: SI277001_RPT
2 Reed Street, Thornaby, UK, TS17 7AF
ISSUE:
F
DATE: 31.10.14
Tel: + 44 (0)1642 617444
PAGE 13 OF 29
Fax: + 44 (0)1642 616447
www.pidesign.co.uk7.2
Safety Instrumented Function – No 4 East Tanks
7.2.1
Sensor Sub-System
The Sensor sub-system comprises of an Endress & Hauser FTL51 Liquiphant with FEL57
2 wire PFM electronic insert. The instrument is ATEX certified II1/2G EExia IIC T6 and has
been subjected to approval to BS EN61508 for use in SIL1/2 applications.
7.2.1.1 Sensor Suitability
The tanks contain Gasoline at atmospheric conditions. The materials of construction of the
level probe and process flange is 316L stainless steel, of which Gasoline has no chemical
effect. The level element is flanged 150lb top mounted so there is no risk of product release
from the instrument tapping.
When the level element is fitted with the FEL57 electronic insert communicating with a safe
area mounted Nivotester FTL325P then the system is self checking for line monitoring
through to the sensor, corrosion monitoring on the tuning fork and power failure to the
Nivotester. On detection of any of the above conditions the output contacts fail open, hence
providing a fail safe output to the logic solver and the alarm contacts fail close, providing
indication to the BPCS diagnostics
7.2.1.2 Sensor Subsystem PFD
For 1oo1 Architecture including 3 channel Nivotester and Liquiphant - Max mode and
Density setting 0.7, Endress and Hauser supply the following figures:
Configuration 4 – FEL 57 with Nivotester FTL325P as three channel device in single channel
mode
λ
SD
= 1.37 x 10
-7
λ
SU
= 4.57 x 10
-7
λ
DD
= 3.38 x 10
-10
λ
DU
= 5.57 x 10
-8
Safe fail fraction 91%
MTTR 72 hours
Functional Test with test key – Annually
Complete function test. e.g. by approaching level – Not required within normal life
Source: E & H Functional Safety Manual SD231F/00/en/ See Appendix 1
Calculated value of PFD of 2.48 x 10
-4
meets the requirements of SIL2.