Test Questions on Safety Instrumented System

In this article, you will find the test questions on the safety instrumented system to evaluate your technical skills on the safety PLC.

Safety Instrumented System Test

Test Questions on Safety Instrumented System

The below list provides all the multiple-choice questions (MCQ) related to the emergency shutdown system used in the oil and gas industries.

Answers are available at the bottom of the article.

1. When 3 Logic solvers processors are performing similar Application program functions, the type of configuration known as

B)Dual redundant
D)Triple modular redundant

2. Safety Instrumented System Document used to define full steps of the SIS workflow is

A)Safety manual
B)Safety Design Document
C)Safety Requirement Specification
D)Layer Of Protection Analysis

3. If the PFD of a system is 1.1E-3, then it falls under


4. IEC Standards used for Safety Instrumented Systems are

A)61508 & 61511
B)61805 & 61511
C)61805 & 61501
D)61508 & 61151

5. Which of the following is not an Independent Protection Layer

B)Check valves
C)Relief valves
D)Operator Intervention to alarms

6. In accordance with IEC61511, how much verification does it need to be performed?

A)Using standard Design guidebooks
B)Using 3rd party certifications

7. Safety Instrumented Systems are to be periodically _____ to ensure their healthiness as per IEC standards.

A)Overhauled at workshop
B)Tested at factory
C)Proof tested

8. Which is the most common form of logic description in Safety Requirement Specifications?

A)Sequential flow chart
B)Text Narrative
C)Function Block Diagram
D)Cause & Effect Diagram

9. Equivalent standard of IEC61511 in ISA


10. How does an SIS most typically reduce risk?

A)Reduces the magnitude of harm
B)Satisfies the legal requirements
C)Reduces the likelihood of harm
D)Satisfies the plant head’s requirements

11. State which statements are True

A)SIS Validation is done only once after the initial installation
B)Both SIS Validation is done only once after initial installation and SIS verification are done after every Shutdown.
C)SIS Verification is done only once in a lifetime
D)SIS Verification & SIS Validation are done after each plant shutdown
E)SIS verification is done after every Shutdown

12. What is the most critical attribute of a Proof test of an SIS component?

A)Test procedure is provided by SIL-certified vendor
B)The test uses automated tools that are connected to a Computerized Maintenance Management System
C)Any known dangerous failure mode that is undetectable by automatic diagnosis would be detected
D)The test is executed in the presence of the equipment danger

13. The ____________ in an Emergency Shutdown valve is used to vent the air to close the valve

A)Air filter regulator
B)Solenoid valve
C)Digital valve controller
D)Booster relay

14. SIS Duplex voting is also represented as

A)2oo3, 1oo2
B)1oo2 , 2oo2
C)2oo2, 1oo1
D)2oo1, 2oo2

15. What is the SIL level when PFDavg < 10-3


16. Maximum time allowed for SIS Repair deferrals with the highest level of approval

A)Irrespective of the Proof test max allowed is 1 year
B)> 50% and < 100% of existing Proof test period
C)>25% of the existing Proof test period
D)>50% of the existing Proof test period

17. State which below statement is True about SIS

A)As the time increases PFD stays increases
B)PFD has no relevance with time
C)As the time increases PFD stays stable
D)As the time increases PFD decreases

18. During plant normal conditions, no electrical current flows through the instrument loop, this is which type of loop.

A)Deenergize to safe
B)Energize to trip
C)Deenergize to trip
D)Energize to Safe

19. Which one is not a Common Cause Failure

A)Using Flowmeter from 2 different technologies
B)Electrical signal of the transmitter is influenced
C)Pressure, Flow Impulse line plugging
D)Two transmitters are connected to one Annubar flow element

20. Redundant systems composed of identical units, identify which of the below can significantly influence system performance with regards to reliability.

A)Redundant configuration
B)Reliability analysis tools
C)More than 2 sensor system
D)Common Cause Failures (CCFs)

21. When it is required to do maintenance on SIS instruments/systems it is required to do


22. A failure mode of the protection system that becomes shutdown if there is a failure in any of its components is known as

A)Detected Safe failure
B)Detected Dangerous failure
C)Fail to Danger
D)Fail to Safe

23. SIS proof test intervals shall be established based upon and SIS configuration

A)Risk reduction factor
B)Mean Time to Repair (MTTR)
C)Safety Integrity Level (SIL)
D)Probability of Failure on Demand

24. Digital valve controllers (Microprocessor-based) for Safety Instrumented Function (SIF) loops

A)Determine the health of final control elements
B)All of the answers
C)Provide valve signature data for historical record and future comparison
D)Test valves to a pre-configure travel limit while the process in on-line

25. In Safety Instrumented System terminology, IPL stands for

A)Independent Protection layer
B)Instrument Prevention Layer
C)Instrumented Protection Layer
D)Independent Production Layer

26. New or modified Safety Function programming shall be verified against its specification by application code review or simulation

A)By program debugging
B)By Human machine interface stations
C)By Engineering programming tool
D)By Emulator software

27. IEC stands for

A)International Electrical Commission
B)International Electro Committee
C)International Electro-technical commission
D)International Electrical Coding

28. SIS stands for

A)Critical Instrument System
B)Safety Instrumented System
C)Safety System Impairment
D)Shutdown Instrument System

29. How many sensors are there in 2oo3 voting configurations


30. A ____ can impact two or more separate elements leading to a total system failure

A)Sensor failure
B)Logic solver failure
C)SIS Failure
D)common cause failure

31. The total probability of failure of an SIS loop is 100% which is in general divided as below for Sensor, Logic Solver & Final element.

A)Sensor – 50%, Logic solver – 15% & Final element – 35%
B)Sensor – 35%, Logic solver – 15% & Final element – 50%
C)Sensor – 50%, Logic solver – 20% & Final element – 30%
D)Sensor – 30%, Logic solver –35% & Final element – 35%

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