Safety Considerations Guide for Triconex General ... - ICEWeb
Safety Considerations Guide for Triconex General ... - ICEWeb Safety Considerations Guide for Triconex General ... - ICEWeb
2 Chapter 1 Safety Concepts Overview Modern industrial processes tend to be technically complex, involve substantial energies, and have the potential to inflict serious harm to persons or property during a mishap. The IEC 61508 standard defines safety as “freedom from unacceptable risk.” In other words, absolute safety can never be achieved; risk can only be reduced to an acceptable level. Safety methods to mitigate harm and reduce risk include: • Changing the process or mechanical design, including plant or equipment layout • Increasing the mechanical integrity of equipment • Improving the basic process control system (BPCS) • Developing additional or more detailed training procedures for operations and maintenance • Increasing the testing frequency of critical components • Using a safety-instrumented system (SIS) • Installing mitigating equipment to reduce harmful consequences; for example, explosion walls, foams, impoundments, and pressure relief systems Safety Considerations Guide for Triconex General Purpose v2 Systems
Overview 3 Protection Layers Methods that provide layers of protection should be: • Independent • Verifiable • Dependable • Designed for the specific safety risk This figure shows how layers of protection can be used to reduce unacceptable risk to an acceptable level. The amount of risk reduction for each layer is dependent on the specific nature of the safety risk and the impact of the layer on the risk. Economic analysis should be used to determine the appropriate combination of layers for mitigating safety risks. Acceptable Risk Level Mechanical Integrity Inherent Process Risk 0 SV Lower Risk SIS Process BPCS* Higher Risk * BPCS–Basic process control system SIS–Safety-instrumented system SV–Safety (relief) valve Figure 1 Effect of Protection Layers on Process Risk When an SIS is required, one of the following should be determined: • Level of risk reduction assigned to the SIS • Safety integrity level (SIL) of the SIS Typically, a determination is made according to the requirements of the ANSI/ISA S84.01 or IEC 61508 standards during a process hazard analysis (PHA). 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: 1 Safety Concepts Overview 2 Hazard
- Page 15 and 16: Hazard and Risk Analysis 5 Hazard a
- Page 17 and 18: Hazard and Risk Analysis 7 Sample S
- Page 19 and 20: Hazard and Risk Analysis 9 Safety L
- 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
Overview 3<br />
Protection Layers<br />
Methods that provide layers of protection should be:<br />
• Independent<br />
• Verifiable<br />
• Dependable<br />
• Designed <strong>for</strong> the specific safety risk<br />
This figure shows how layers of protection can be used to reduce unacceptable risk to an<br />
acceptable level. The amount of risk reduction <strong>for</strong> each layer is dependent on the specific nature<br />
of the safety risk and the impact of the layer on the risk. Economic analysis should be used to<br />
determine the appropriate combination of layers <strong>for</strong> mitigating safety risks.<br />
Acceptable Risk Level<br />
Mechanical Integrity<br />
Inherent Process Risk<br />
0<br />
SV<br />
Lower Risk<br />
SIS<br />
Process<br />
BPCS*<br />
Higher Risk<br />
* BPCS–Basic process control system<br />
SIS–<strong>Safety</strong>-instrumented system<br />
SV–<strong>Safety</strong> (relief) valve<br />
Figure 1<br />
Effect of Protection Layers on Process Risk<br />
When an SIS is required, one of the following should be determined:<br />
• Level of risk reduction assigned to the SIS<br />
• <strong>Safety</strong> integrity level (SIL) of the SIS<br />
Typically, a determination is made according to the requirements of the ANSI/ISA S84.01 or<br />
IEC 61508 standards during a process hazard analysis (PHA).<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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