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SIL Capable

An Overview of Hochiki's SIL2 Capable Fire Detection Range.


What is SIL?

SIL is an acronym for Safety Integrity Level, and is a system used to quantify and qualify the requirements for Safety Instrumented Systems.


The International Electro-technical Commission (IEC) introduced the following industry standards to assist operators with quantifying the safety performance requirements for hazardous operations:


IEC 61508
Functional Safety of Electrical/Electronic/
Programmable Electronic Safety-Related Systems


IEC 61511
Safety Instrumented Systems for the Process Industry Sector


These standards have been widely adopted in the hydrocarbon and oil and gas industries as a means of improving safety and availability of Safety Instrumented Systems.


Safety Integrity Levels are part of a larger scheme called Functional Safety that deals with techniques, technologies, standards and procedures that help operators protect against hazards. Simply put, SIL levels are targets applied to the reliability and performance of the safety systems used to protect hazardous activities such as hydrocarbon refining or production.


Main Benefits of our SIL2 Range

SIL Capable

SIL2 Capable Range

Figure 1

Hazardous Activity

SIL Levels

How are they calculated?

There are four SIL levels. The higher the perceived associated risk, the higher the performance required of the safety system and therefore the higher the SIL rating number.


Once the scope of an activity is determined, the operator can identify the possible hazard(s) and then assess their potential severity. The risk associated with a hazard is identified by assessing the likely frequency of occurrence and the potential consequences if the hazard is realised.


The operator must then assign a number for the severity of consequence and frequency.

The figure above shows multiple layers of protection are used to develop the required safety strategy. Safety Instrumented System has been highlighted because this is the layer that applies to Hochiki's SIL 2 capable fire detection equipment.


The SIS assists in reducing the frequency of the likely manifestation of the hazard and therefore improves the reliability of the system. The consequence of a failure is not addressed by SIS but by other aspects of the risk reduction strategy.

Figure 2


These numbers are then entered into a matrix (see example below) to allow the operator to assign the required SIL rating to protect against the hazard.


Many tools are available to assist an operator with this process, for example HAZOP (Hazard & Operability) software.




Our SIL 2 capable range of products has been independently assessed by Engineering Safety Consultants Limited and is considered capable for use in a SIL 2, low demand Safety Function with regard to random failure rates.


Individual certificates are available to download from our store.

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