Safety Considerations Guide for Triconex General ... - ICEWeb

Hazard and Risk Analysis 7
Sample SIL Calculation
As a PES, the Tri-GP controller is designed to minimize its contribution to the SIL, thereby
allowing greater flexibility in the SIS design.
99.9999 0.000001
R
I
S
K
R
E
D
U
C
T
I
O
N
99.999 0.00001
99.99 0.0001
99.90 0.001
99.00 0.01
90.00 0.1
Tri-GP
PES*
SIL 2 SIS
Percent
Availability
PFD
Risk Measures
Figure 3
Comparison of Percent Availability and PFD
* Tri-GP controller module failure rates, PFD avg , Spurious Trip Rate, and Safe Failure Fraction
(SFF) calculation methods have been independently reviewed by TÜV Rheinland. The numbers
presented here (and in the following tables) are typical. Exact numbers should be calculated for
each specific system configuration. Contact the Invensys Global Customer Support (GCS) center
for details on calculation methods and options related to the Tri-GP controller.
Safety Integrated System
3 Pressure
Transmitters (2oo3)
Sensors
3 Temperature
Transmitters (2oo3)
TMR Controller
(2oo3)
PES/Logic Solver
2 Block Valves
in Series (1oo2)
Final Elements
Figure 4
Simplified Diagram of Key Elements
Safety Considerations Guide for Triconex General Purpose v2 Systems