Last edit: 03/03/2023
The requirements of this standard over the years have been aligned with similar requirements of international standards (ISO and IEC) and European (EN) in order to achieve a similar level of risk reduction. The main differences concern the different methods and analytical approaches used, ANSI provides many indications and other safety-related information beyond what is contained in the ISO, which has a "directive" nature.
The foundation of the standard occurred in 1990. The second revision, after the one in 1997, approved by ANSI in 2003, was a major rewrite that included data update. The 2010 version already incorporated new requirements and information including: Protective Stops, Perimeter Guarding, Muting, Manual Suspension (Bypass), Emergency Stop including rope/cable pulls, three-position Enabling Devices, Hold-to-run Control, Guard Interlocking Switches with guard locking, and Pres-ence-sensing Device Initiation (PSDI).
The working group, of which GT-Engineering is part, has developed the new version of the standard published in October 2019. There are many new aspects for example; the traditional term "safeguarding" will in many cases be replaced by the term "risk reduction measures" and the informative annexes have been extended.
The intent is to maintain a high level of security for safety-related functions, but also to allow a feasible risk reduction that can reasonably be justified through the process of a documented risk assessment that meets the required risk reduction.
News of the new edition
The new edition (October 2019) of ANSI B11.19 is the result of a revision process that lasted over four years.
The result of this revision is a standard that more than doubled in size compared to the previous edition.
The risk reduction measures included in the new standard follow the same method of the three steps of the international standard ISO 12110, however, the second step of risk reduction, called "Engineering Controls" includes a wide choice of reduction techniques and the measures have been further divided with a more specific focus for each subset.
To help the reader with the new format of the standard, in particular for readers who are familiar with the previous 2010 edition, an attachment has been introduced: Annex P which provides comparisons both from old to new and from new to old of the 2010 editions and 2019, and also highlights topics introduced in the latest edition.
The new edition also contains terminological changes. An example is in the title previously named "Performance Criteria for Safeguarding ", the title is now" "Performance Requirements for Risk Reduction Measures."
The reason is that the previous editions of ANSI B11.19 included the term "safeguarding" although the techniques for reduction are not limited to only step 2 of the hierarchy.
Due to the ever increasing progress, the standard has also tried to align by introducing attachments that specify the concept of achieving a safe condition including:
Annex J – Measurement & Calculation of System Performance to Achieve a Safe Condition
Annex K – Achieving a Safe Condition
Annex L – Safety Functions for Power Drive Systems
Annex M – Supplier Information for Time and Distance to Achieve a Safe Condition
Therefore, the new standard integrates in a single document all the means that the machine manufacturer or the user. In USA the user often takes care of completing the machine safeguarding and therefore the distinction between manufacturer and user is not so clear as in Europe. The new edition aligned with other USA standards, reducing conflicts in terminology and introducing new measures or approaches not addressed in any other standards.
In Europe, CEN takes care of the "mechanical" standards and IEC of the electrical. In USA there are several standardisation bodies. It is therefore important that they do not overlap. They have a tradition and a sot of "self-control" in order "not to step on someone else" standard.