Functional Safety | BS EN 61508


Functional safety is the part of overall safety that depends on a system or equipment operating correctly in response to its inputs. Functional safety relies on active systems to detect potentially dangerous conditions and to activate protective or corrective mechanisms to prevent or mitigate hazards.

For a common example, let's take a storage tank for inflammable liquid. A sensor detects when there is a high liquid level in the tank, which in turn triggers a mechanism that cuts off the filling of the tank.

Increasingly embedded software is also playing a central role in safety and control systems.  

People have high expectations of such systems, and a failure can mean loss of trust, injury, damage, environmental degradation, or death. Functional safety then, is important for both suppliers and end users.

The BS EN 61508 series contains a set of requirements that can help you as a product/system designer, specifier or end user to deploy appropriate safety systems to reduce these failures. It can also make complying with safety regulation more straightforward.


Who should use the BS EN 61508 series?

Engineers, designers, specifiers and users of any products or systems that incorporate electronic / electric / programmable safety systems.

What are some examples of functional safety applications?

  • Emergency shut-down systems
  • Fire and gas systems
  • Turbine control
  • Gas burner management
  • Crane automatic safe-load indicators
  • Guard interlocking and emergency stopping systems for machinery
  • Medical devices
  • Dynamic positioning (control of a ship's movement when in proximity to an offshore installation)
  • Fly-by-wire operation of aircraft flight control surfaces
  • Railway signalling systems (including moving block train signalling)
  • Variable speed motor drives used to restrict speed as a means of protection
  • Automobile indicator lights, anti-lock braking and engine-management systems
  • Remote monitoring, operation or programming of a network-enabled process plant
  • An information-based decision support tool where erroneous results affect safety.

What are the benefits?

Easier compliance. If you use the BS EN 61508 series, Safety Regulators will see this as representing accepted good practice. This can help speed the compliance process.

Achieve tolerable risk. The standards can help you achieve tolerable risk from the development of the safety requirements specification, to design, operation and maintenance, modification and decommissioning.

Reduce over-engineering. Save money and materials by knowing what level of safety is appropriate.

Increase trust. Less risk means more trust from your customers and stakeholders. 


The BS EN 61508 series on functional safety comes in 7 parts:

Read more about the parts and purchase by following the links below:

BS EN 61508-1:2010 General requirements

BS EN 61508-2:2010 Requirements for electrical/ electronic/ programmable electronic safety-related systems

BS EN 61508-3:2010 Software requirements

BS EN 61508-4:2010 Definitions and abbreviations

BS EN 61508-5:2010 Examples of methods for the determination of safety integrity levels

BS EN 61508-6:2010 Guidelines on the application of IEC 61508-2 and IEC 61508-3

EN 61508-7:2010 Overview of techniques and measures

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John Glover


 


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