The Third Level of the Hierarchy: Information for Use

This entry is part 3 of 3 in the series Hierarchy of Controls

I’ve written about the Hierarchy of Controls in past posts, but I’ve focused on the ‘engineering’ side of the control equation: Physical changes to machine design to eliminate hazards, and mechanical or electrical control systems that can reduce risk.

The first two levels of the Hierarchy, Elimination/Substitution and Engineering Controls, are typically more challenging to apply in most people’s minds, because expert knowledge is required. These levels are also more effective in controlling risk than the subsequent levels.

The Third Level

iStock_000009386795Small - Photo of Instruction manualThe third level of the Hierarchy is ‘Information for Use’, sometimes abbreviated as ‘IFU.’ This level is deceptively simple, and is frequently the level people want to jump to when the other controls seem too difficult to implement. Done well, information for use can make a significant contribution to risk control. Unfortunately, it’s done poorly or not at all more often than it’s done well.

Information for use includes:

  • Instructions and Manuals;
  • Operator Device tags and Legend Plates;
  • HMI screens;
  • Hazard Warning signs and labels;
  • Training Materials (text, video, audio) and Training (face-to-face, webinars, self-directed);
  • Sales and marketing materials.

Information for use is needed in all the stages of the product life cycle: Transportation, Installation, Commissioning, Use, Maintenance, Service, Decommissioning and Disposal [1]. At each stage in the life cycle, the content of the information and the presentation may be different. In every stage it can make a significant contribution to risk reduction by communicating the safe approach to the tasks in that stage, and the risks related to those tasks. The information should include the intended use and the foreseeable misuses of the product. This is a legal requirement in the EU [2], and is a best-practice in North America.

In this article I’m going to focus on instruction manuals. If you’re interested in Hazard Warnings, including signs, labels, and integration into manuals and instructions, watch for a future post on this topic.

Legal requirements and standards

In the European Union, the legal obligation to provide information with a product is enshrined in law [2].
No North American jurisdictions make an explicit requirement for instructions or information for use in law, but many product specific standards include requirements for the content of manuals.

CSA Z432 [3] outlines requirements for content in Clause 17, and in EN 60204-1 [7]. IEC 62079 [4], provides guidance on the design and presentation of instructions. ANSI Z535.6 [5], provides specific instructions on inclusion of hazard warnings in manuals and instructions.

Training requirements are also discussed in CSA Z432 [3], Clause 18.

5% Discount on ISO and IEC Standards with code: CC2011

In the USA, providing information for use with a product is considered to be sound ‘due diligence’, however, providing information on residual risk is often seen by liability lawyers as dangerous, since manufacturers are providing information, in writing, that their product is not ‘perfectly safe.’ If you’ve read anything I’ve written on risk assessment, you’ll know that there is no such state as ‘perfectly safe.’ If a hazard exists, a potential for harm exists, a probability can be assessed and thus risk exists, however remote that risk may be. I think that this argument by some liability lawyers is fatuous at best.

Kenneth Ross, one of the leading product liability lawyers in the USA, discusses the requirements for warnings and instructions in an article published in 2007 [6]. In the article, he explains the US requirements:

“Product sellers must provide “reasonable warnings and instructions” about their products’ risks. The law differentiates warnings and instructions as follows:

“Warnings alert users and consumers to the existence and nature of product risks so that they can prevent harm either by appropriate conduct during use or consumption or by choosing not to use or consume.”

Instructions “inform persons how to use and consume products safely.”

A court has held that warnings, standing alone, may have no practical relevance without instructions and that instructions without warnings may not be adequate.

Therefore, when the law talks about the “duty to warn,” it includes warnings on products in the form of warning labels; safety information in instructions; instructions that affirmatively describe how to use a product safely; and safety information in other means of communication such as videos, advertising, catalogs and websites.

The law says that a manufacturer has a duty to warn where: (1) the product is dangerous; (2) the danger is or should be known by the manufacturer; (3) the danger is present when the product is used in the usual and expected manner; and (4) the danger is not obvious or well known to the user.”

Read Mr. Ross’ latest article on warnings.

This practical and sensible approach is very similar to that in the EU. Note the requirement that “instructions that affirmatively describe how to use a product safely.” The  old list of “don’ts” doesn’t cut it – you must tell your user how to use the product in an affirmative way.

Second Best

So why is it that so many manufacturers settle for manuals that are barely ‘second best’? In many companies, the documentation function is:

  • Not seen to add value to the product;
  • not understood to have legal import in limiting product liability;
  • given little effort.

The perception seems to be that manuals are produced primarily to fill filing cabinets and that customers don’t use the information provided. This leads to manuals that are written after-the-fact by engineers, or worse, the role of ‘technical writer’ is seen to be an entry level position often filled by interns or co-op students.

End-user training is frequently given even less thought than the manuals. When designed together, the manual will support the training program, and the trainers can use the manual as one of the primary training tools. This provides continuity, and ensures that the training process is properly documented.

iStock_000012657812Small - Techncial ManualMy experience is that few engineers are excellent writers. There are some, no doubt. Writing manuals takes a sound understanding of educational theory, including an understanding of the audience to whom the material is directed. The level of technical sophistication required for a simple household product is completely different from that required for the technical support manual for an industrial welding laser.
The engineers designing and integrating an industrial system are often too close to the design of the product to be able to write effectively to the target audience. Assumptions about the level of education that the user will have are often incorrect, and key steps may be skipped because they are assumed to be ‘common knowledge.’

Quality documentation is also a customer service issue. Products that are well documented require less customer service support, and when customers do need support, they are generally more satisfied with the result.

New Delivery Methods

The delivery methods for technical documents have changed considerably in recent years. Large, ring-bound paper manuals are being displaced by on-line, interactive documentation that can be accessed at the user interface. The use of PDF-format manuals has jumped, and this brings in the ability to link error messages generated by the control system to the sections of the manual that related to that aspect of the system. Video and animations can be added that provide at-a-glance understanding of the operation of the machinery. WiFi networks in industrial facilities, along with the acceptance of mobile pad-computing devices like the Apple iPad, mean users can have the instructions where they need them, and technicians and service personnel can take the manual with them to the area where a problem exists, and can use the documents even in very low-light conditions.

Finding technical writing resources can be a challenge, particularly if you are looking to move away from paper to electronic documentation. The standards mentioned in this article are a good place to start.
Documentation can range from writing through technical illustrations, animation and video production. Finding individuals who can provide you with professional services in these areas in a timely way and at a reasonable price is not an easy task. If you need assistance ranging from a few questions that need answers to hiring a technical writer, Compliance InSight Consulting can help. Contact me for more information!

Are your product manuals as good as they could be? What kinds of challenges have you had with getting them written, or used? Add your comments below!


5% Discount on ISO and IEC Standards with code: CC2011

[1]    “Safety of machinery – General principles for design – Risk assessment and risk reduction”, ISO Standard 12100, 2010

[2]    “DIRECTIVE 2006/42/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 17 May 2006 on machinery, and amending Directive 95/16/EC”, Annex 1, Clause 1.7, European Commission, 2006.

[3]    “Safeguarding of Machinery”, CSA Standard Z432, Canadian Standards Association, 2004.

[4]    “Preparation of instructions – Structuring, content and presentation”, IEC Standard 62079, International Electrotechnical Commission, 2001.

[5]    “American National Standard For Product Safety Information in Product Manuals, Instructions, and Other Collateral Materials”, ANSI Standard Z535.6, American National Standards Institute, 2006.

[6]    K. Ross. “Danger! The Legal Duty to Warn and Instruct”, Risk Management Magazine, [web] 2007, Available: No longer available.

[7]      “Safety of machinery — Electrical equipment of machines — Part 1: General requirements”, CENELEC Standard EN 60204-1, CENELEC, 2009.

Inconsistencies in ISO 13849-1:2006

This entry is part 7 of 8 in the series Circuit Architectures Explored

I’ve written quite a bit recently on the topic of circuit architectures under ISO 13849-1, and one of my readers noticed an inconsistency between the text of the standard and Figure 5, the diagram that shows how the categories can span one or more Performance Levels.

ISO 13849-1 Figure 5
ISO 13849-1, Figure 5: Relationship between Categories, DC, MTTFd and PL

If you look at Category 2 in Figure 5, you will notice that there are TWO bands, one for DCavg LOW and one for DCavg MED. However, reading the text of the definition for Category 2 gives (§6.2.5):

The diagnostic coverage (DCavg) of the total SRP/CS including fault-detection shall be low.

This leaves some confusion, because it appears from the diagram that there are two options for this architecture. This is backed up by the data in Annex K that underlies the diagram.

The same confusion exists in the text describing Category 3, with Figure 5 showing two bands, one for DCavg LOW and one for DCavg MED.

I contacted the ISO TC199 Secretariat, the people responsible for the content of ISO 13849-1, and pointed out this apparent conflict. They responded that they would pass the comment on to the TC for resolution, and would contact me if they needed additional information. As of this writing, I have not heard more.

So what should you do if you are trying to design to this standard? My advice is to follow Figure 5. If you can achieve a DCavg MED in your design, it is completely reasonable to claim a higher PL. Refer to the data in Annex K to see where your design falls once you have completed the MTTFd calculations.

Thanks to Richard Harris and Douglas Florence, both members of the ISO 13849 and IEC 62061 Group on LinkedIn for bringing this to my attention!

If you are interested in contacting the TC199 Secretariat, you can email the Secretary, Mr. Stephen Kennedy. More details on ISO TC199 can be found on the Technical Committee page on the ISO web Site.

EC Machinery Working Group meets

From our friends at

It is now more than a year since the new Machinery Directive (2006/42/EC) came into force, but the situation is still fairly fluid in some respects. The EC Machinery Working Group meets regularly to discuss matters relating to the Directive and corresponding standards; the last meeting took place on 21/22 December. According to the Stakeholder Report published in the UK by BIS (the Department for Business, Innovation & Skills), a number of issues were discussed, which demonstrates that the Machinery Directive is not as ‘black and white’ as might be expected.

For example, EN 12635 (Industrial, commercial and garage doors and gates – Installation and use) is currently harmonised to the Machinery Directive, but the UK has raised a formal objection against this standard, as it would appear that there is scope for improvement. Other topics under discussion ranged from variable reach trucks, tail lifts and loader cranes, to stave splitters, dynamometers and ‘grey’ imports of machinery.

If you would like more information, copies of the current and previous Stakeholder Reports are available in PDF format from the UK Department of Business Information & Skills (BIS) web site.

Machinery Directive stakeholder report: February 2011 (PDF, 81 Kb)

Machinery Directive Working Group held on 1-2 June 2010, Brussels (PDF, 56 Kb)