Cookie consent(s)
We use cookies on our website to personalise content and ads, to provide social media features and to analyse traffic to our website. To provide you with a convenient online experience and to improve our communications, please click "ACCEPT ALL". By doing so, you consent to the processing and sharing of your information with our social media, advertising and analytics partners cookies described in detail here You can revoke your consent(s) at any time in the settings. Click here to adjust your cookie consents individually.
Data protection declaration | Legal Notices
Settings
Jubilee Signet

Selection of Functional Safety Standards - Where to start?

“Using an appropriate standard” the words which send dread through many trying to understand the use of functional safety standards. With over a dozen standards (and growing) available, many with overlapping scopes the question is:
  • What is appropriate?
  • What if we get it wrong?
  • How do I know?
These are all questions we have asked at one point or another. In this short article we look at how the appropriate standard may be selected.

Technology

The first question is one of context. The development of components and sub systems is often done out of specific context. This allows one device to serve several applications, should the specification allow.
Machinery is the classical example for this. ISO 13849 and IEC 62061 both cover this type of development.
However, they are not the only standards for this. Electro-sensitive protective equipment (light barriers, object detection systems for example) may use IEC 61496 for example as this is specific to the technologies utilised in this field.
Tip #1: If Context is not specific, select by technology.
Context
Where the end application is known this allows the use of the sector specific standards. An example of this is IEC 61511 for the process industry, ISO 19014 of Earth Moving Machinery and ISO 60601 for medical.
These standards typically provide guidance or integrating technologies into a specific application and then integrating the measures for safe operation, maintenance and modification, considering the technology specific elements.
Tip #2: Where context is known a sector specific standard may be more appropriate.
Supply chain
It is possible for a single organisation to have requirements to utilise different standards. This is especially true of system integrators who sit on a border between the component manufacturers.
The key is to understand the position your organisation or project holds within the overall safety supply chain. Consider the tasks which your organisation or project are undertaking. If these involve operation, maintenance or modification then it is likely you position is at the operational end of the scale. If the activities are those of design assurance and performance documentation, then it is likely near the component manufacturer.
This is not a concept that is described in one single place in the functional safety world, with each standard setting its own position there is more of a collective approach. However if we draw from the Cyber Security field and IEC 62443 we may derive figure 1 below.
Figure is derived from IEC 62443 but adapted for the functional safety standards in the machinery and process sectors showing how the differing standards may interrelate through the supply chain.
There is a single caveat to this selection and that is in machinery. If as an OEM, you seek to place a safety-related machine or device on the market then compliance with the machinery directive may be required. This being the case selection of the cited functional safety standard, ISO 13849 is the default choice. The use of another functional safety standard, such as IEC 62061 or IEC 61508 should only be undertaken with good and justifiable reason.
Tip #3: If unsure whether to apply a sector or technology standard assess the activities you are undertaking.
What about IEC 61508?
IEC 61508 has not so far been mentioned. This is not because the basic safety standard lack applicability, it does not, rather because it is almost universally applicable.
IEC 61508 should be applied when there is no technology or sector specific standard that fits the needs. Examples of this are high innovation products or processes and products with may not fall under the categories of machinery.
The exception to this rule is medical products which fall under IEC 60601. These are specifically not covered by IEC 61508 at present.
This is not to say that IEC 61508 is any less important or applicable, rather that it is almost always an open option.
Tip #4: IEC 61508 is always an option.

Conclusion

To conclude. There are many routes towards proving functional safety. The four tips listed, if taken in order should provide a powerful guide to selecting the most appropriate standard.
If Context is not specific, select by technology.
Where context is known a sector specific standard may be more appropriate
If unsure whether to apply a sector or technology standard, assess the activities you are undertaking.
IEC 61508 is always an option.
It should finally be said that there is often not a right and wrong answer. Rationalise a decision, record the rational and start the journey. If it is found halfway that a more appropriate path exists, then take it! These standards are interrelated so it is unlikely that your efforts will be wasted.
Contact us