ISA CAP Safety & Regulatory Compliance 2 — Questions and Answers
Question 1: Which IEC standard defines the functional safety requirements for electrical/electronic/programmable electronic safety-related systems?
- IEC 61511
- IEC 61508 (Correct answer)
- IEC 62443
- IEC 60601
Correct answer: IEC 61508
IEC 61508 is the foundational functional safety standard for E/E/PE safety-related systems across all industries.
Question 2: In a Safety Instrumented Function (SIF), what is the primary purpose of the final element?
- To detect the hazardous condition
- To process the safety logic
- To take action to bring the process to a safe state (Correct answer)
- To communicate alarms to operators
Correct answer: To take action to bring the process to a safe state
The final element (e.g., valve, motor) executes the protective action to move the process to a safe state when a demand occurs.
Question 3: What does 'proof test interval' refer to in the context of functional safety?
- The time between SIL assessments
- The periodic test performed to reveal dangerous hidden failures (Correct answer)
- The interval between process safety reviews
- The frequency of HAZOP meetings
Correct answer: The periodic test performed to reveal dangerous hidden failures
Proof test interval is the time between scheduled tests designed to detect dangerous undetected failures in safety instrumented systems.
Question 4: Which US regulation requires Process Hazard Analysis (PHA) for highly hazardous chemicals?
- EPA RMP Rule (40 CFR Part 68)
- OSHA PSM Standard (29 CFR 1910.119) (Correct answer)
- NFPA 72
- DOT 49 CFR Part 195
Correct answer: OSHA PSM Standard (29 CFR 1910.119)
OSHA's Process Safety Management standard (29 CFR 1910.119) mandates PHA for processes with highly hazardous chemicals above threshold quantities.
Question 5: What is the meaning of 'SFF' (Safe Failure Fraction) in IEC 61508?
- The ratio of safe failures to total failures (Correct answer)
- The percentage of time a system operates safely
- The fraction of tests that detect failures
- The proportion of redundant channels in a system
Correct answer: The ratio of safe failures to total failures
SFF is the ratio of the sum of safe failure rates plus dangerous detected failure rates to the total failure rate.
Question 6: Under IEC 61511, who is responsible for defining the Safety Requirements Specification (SRS)?
- The SIS vendor
- The process owner/operator (Correct answer)
- The certification body
- The insurance provider
Correct answer: The process owner/operator
IEC 61511 places responsibility on the process owner/operator to define the SRS, which specifies the functional and integrity requirements for each SIF.
Question 7: Which hazard analysis technique uses a tabular format with guide words (NO, MORE, LESS, AS WELL AS) to identify process deviations?
- Fault Tree Analysis (FTA)
- Failure Mode and Effects Analysis (FMEA)
- HAZOP (Correct answer)
- What-If Analysis
Correct answer: HAZOP
HAZOP (Hazard and Operability Study) applies structured guide words to process parameters to systematically identify deviations and their consequences.
ISA CAP Safety & Regulatory Compliance 2
Which IEC standard defines the functional safety requirements for electrical/electronic/programmable electronic safety-related systems?