SIS and Hazardous Area Quiz

1. Safety Integrity Level: Defined in IEC 61508 and IEC 61511.
2. Safety instrumented systems in the process industry: It is the process sector standard for SIS.
3. ≥ 10⁻³ to < 10⁻²: SIL 1: 10⁻² to 10⁻¹, SIL 2: 10⁻³ to 10⁻², SIL 3: 10⁻⁴ to 10⁻³.
4. Two of three sensors must trip: It balances safety and spurious trips.
5. Dangerous undetected failures: Proof tests find failures the system cannot detect itself.
6. Likely in normal operation: Zone 0 continuous, zone 1 likely, zone 2 unlikely.
7. Zones 0, 1 and 2: ia is the highest intrinsic safety level.
8. Hydrogen and acetylene: IIC is the most easily ignited group.
9. 135 °C: T1 450, T2 300, T3 200, T4 135, T5 100, T6 85 °C.
10. Flameproof enclosure: Ex d contains an internal explosion.
11. Zone 1: Ga zone 0, Gb zone 1, Gc zone 2.
12. Loss of power causes the safe action: Fail safe design: power loss leads to the safe state.
13. Safe and dangerous detected failures as a share of all failures: SFF = (λS + λDD) ÷ total λ.
14. Authorisation and compensating measures: Bypasses must be controlled under the site procedure.
15. Determine the required risk reduction and SIL target: Layer of protection analysis sets the SIL target.

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Yes. After you check your answers, each question shows the correct answer and a short explanation.

See the Interview Q&A section of instrumentationblog.in and the linked article below.