Safety Considerations Guide for Triconex General ... - ICEWeb
Safety Considerations Guide for Triconex General ... - ICEWeb Safety Considerations Guide for Triconex General ... - ICEWeb
8 Chapter 1 Safety Concepts This table provides simplified equations for calculating the PFD avg for the key elements in an SIS. Once the PFD avg for each element is known, an SIL can be determined. Table 1 Simplified Equations for Calculating PFD avg Description Equation Variables (Supplied by the Manufacturer) Sensors To calculate PFD avg for sensors (2oo3) PFD avg = ( DU *TI) 2 + 1/2** DU *TI = failure rate DU=dangerous, undetected failure rate TI= test interval in hours = common cause factor Block Valves To calculate PFD avg for block valves (1oo2) in series (final elements) PFD avg = 1 / 3 ( DU *TI) 2 + 1/2** DU *TI = failure rate DU=dangerous, undetected failure rate TI= test interval in hours = common cause factor SIF To calculate PFD avg for a safety instrumented function SIF PFD avg = Sensors PFD avg + Block Valves PFD avg + Controller PFD avg Note Equations are approximate To determine the SIL, compare the calculated PFD avg to the figure on page 5. In this example, the system is acceptable as an SIS for use in SIL2 applications. Table 2 Determining the SIL Using the Equations DU TI PFD Result Pressure Transmitters (2oo3) .03 2.0E-06 13140 1.1E-03 Temperature Transmitters (2oo3) .03 2.6E-06 13140 1.7E-03 Total for Sensors Block Valves (1oo2) .02 2.2E-06 13140 5.7E-04 2.8E-03 Total for Block Valves 0.6E-03 Tri-GP Controller 13140 1.0E-04 0.1E-03 PFD avg for SIF 3.5E-03 For additional information on SIL assignment and SIL verification, visit the Premier Consulting Services web site at www.premier-fs.com. Safety Considerations Guide for Triconex General Purpose v2 Systems
Hazard and Risk Analysis 9 Safety Life Cycle Model The necessary steps for designing an SIS from conception through decommissioning are described in the safety life cycle. Before the safety life cycle model is implemented, the following requirements should be met: • Complete a hazard and operability study • Determine the SIS requirement • Determine the target SIL EXIT No START Design conceptual process Perform process hazard analysis and risk assessment Apply non-SIS protection layers to prevent identified hazards or reduce risk SIS required Yes Define target SIL Develop safety requirements document (Step 1) Perform SIS conceptual design and verify it meets the SRS (Step 2) Perform SIS detail design (Step 3) SIS installation, commissioning, and pre-startup acceptance test (Step 4) Modify Establish operation and maintenance procedure (Step 5) Pre-start-up safety review assessment (Step 6) SIS start-up operation, maintenance, periodic functional testing (Steps 7 and 8) Modify or decommission SIS Decommission Conceptual process design SIS decommissioning (Step 9) S84.01 Concern (Step 3) Figure 5 Safety Life Cycle Model Safety Considerations Guide for Triconex General Purpose v2 Systems
- Page 1 and 2: Triconex General Purpose v2 Systems
- Page 3 and 4: Contents Preface vii Summary of Sec
- Page 5 and 6: Contents v Partitioned Processes. .
- Page 7 and 8: Preface This guide provides informa
- Page 9 and 10: Preface ix • All other requests a
- Page 11 and 12: 1 Safety Concepts Overview 2 Hazard
- Page 13 and 14: Overview 3 Protection Layers Method
- Page 15 and 16: Hazard and Risk Analysis 5 Hazard a
- Page 17: Hazard and Risk Analysis 7 Sample S
- Page 21 and 22: Hazard and Risk Analysis 11 • Eac
- Page 23 and 24: Safety Standards 13 CAN/CSA-C22.2 N
- Page 25 and 26: 2 Application Guidelines Overview 1
- Page 27 and 28: General Guidelines 17 General Guide
- Page 29 and 30: Guidelines for Triconex Controllers
- Page 31 and 32: Guidelines for Triconex Controllers
- Page 33 and 34: Guidelines for Triconex Controllers
- Page 35 and 36: Guidelines for Triconex Controllers
- Page 37 and 38: Guidelines for Triconex Controllers
- Page 39 and 40: Guidelines for Triconex Controllers
- Page 41 and 42: 3 Fault Management Overview 32 Syst
- Page 43 and 44: System Diagnostics 33 System Diagno
- Page 45 and 46: Operating Modes 35 Operating Modes
- Page 47 and 48: Module Diagnostics 37 Analog Output
- Page 49 and 50: Module Diagnostics 39 Calculation f
- Page 51 and 52: Module Diagnostics 41 External Comm
- Page 53 and 54: 4 Application Development Developme
- Page 55 and 56: Development Guidelines 45 Array Ind
- Page 57 and 58: Setting Scan Time 47 application. T
- Page 59 and 60: Sample Safety-Shutdown Programs 49
- Page 61 and 62: Sample Safety-Shutdown Programs 51
- Page 63 and 64: Sample Safety-Shutdown Programs 53
- Page 65 and 66: Sample Safety-Shutdown Programs 55
- Page 67 and 68: Sample Safety-Shutdown Programs 57
8 Chapter 1 <strong>Safety</strong> Concepts<br />
This table provides simplified equations <strong>for</strong> calculating the PFD avg <strong>for</strong> the key elements in an<br />
SIS. Once the PFD avg <strong>for</strong> each element is known, an SIL can be determined.<br />
Table 1<br />
Simplified Equations <strong>for</strong> Calculating PFD avg<br />
Description<br />
Equation<br />
Variables<br />
(Supplied by the Manufacturer)<br />
Sensors<br />
To calculate<br />
PFD avg <strong>for</strong><br />
sensors (2oo3)<br />
PFD avg = ( DU *TI) 2<br />
+ 1/2** DU *TI<br />
= failure rate<br />
DU=dangerous, undetected failure rate<br />
TI= test interval in hours<br />
= common cause factor<br />
Block<br />
Valves<br />
To calculate<br />
PFD avg <strong>for</strong><br />
block valves<br />
(1oo2) in series<br />
(final elements)<br />
PFD avg = 1 / 3 ( DU *TI) 2<br />
+ 1/2** DU *TI<br />
= failure rate<br />
DU=dangerous, undetected failure rate<br />
TI= test interval in hours<br />
= common cause factor<br />
SIF<br />
To calculate<br />
PFD avg <strong>for</strong> a<br />
safety<br />
instrumented<br />
function<br />
SIF PFD avg =<br />
Sensors PFD avg +<br />
Block Valves PFD avg +<br />
Controller PFD avg<br />
Note<br />
Equations are approximate<br />
To determine the SIL, compare the calculated PFD avg to the figure on page 5. In this example,<br />
the system is acceptable as an SIS <strong>for</strong> use in SIL2 applications.<br />
Table 2<br />
Determining the SIL Using the Equations<br />
DU TI PFD Result<br />
Pressure Transmitters (2oo3) .03 2.0E-06 13140 1.1E-03<br />
Temperature Transmitters (2oo3) .03 2.6E-06 13140 1.7E-03<br />
Total <strong>for</strong> Sensors<br />
Block Valves (1oo2) .02 2.2E-06 13140 5.7E-04<br />
2.8E-03<br />
Total <strong>for</strong> Block Valves<br />
0.6E-03<br />
Tri-GP Controller 13140 1.0E-04 0.1E-03<br />
PFD avg <strong>for</strong> SIF<br />
3.5E-03<br />
For additional in<strong>for</strong>mation on SIL assignment and SIL verification, visit the Premier Consulting<br />
Services web site at www.premier-fs.com.<br />
<strong>Safety</strong> <strong>Considerations</strong> <strong>Guide</strong> <strong>for</strong> <strong>Triconex</strong> <strong>General</strong> Purpose v2 Systems
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