Machine Safety: Which safety circuit design is required?

When considering safety circuit designs and compliance requirements, look at B level versus C level safety standards and their approval dates. See levels of machine safety standards graphic.

07/04/2014


Machine safety standards are in levels: A) Basic safety standards apply to industry, B) Group safety standards apply to a defined group or type of machinery, and C) Specialists standards apply to one specific kind of machine, such as mechanical stamping,First of all, is everyone familiar with “B” level and “C” level machine safety standards? Secondly, is everyone familiar with the importance of approval dates of safety standards, particularly when contrasting called out compliance requirements?

Machine safety standards: 3 levels

Let’s begin by looking at the graphic showing example machine safety standards in their respective A, B, and C levels: 

A. Basic safety standards apply to industry.

B. Group safety standards apply to a defined group or type of machinery.

C. Specialists standards apply to one specific kind of machine, such as mechanical stamping, injection molding, converting, etc. 

By looking at the example standards per level, it is easy to understand what is meant by a “B” level versus a “C” level machine safety standard. 

Referenced dates matter

Additionally, when a standard is published, it is also designated via the date it was reviewed and approved. Internal to this process, a standard’s working committee will usually review all content within a standard and either update or not update any specific requirement or miscellaneous information. This can include any normative or informative other referenced standards. These other standards may or may not include a specifically dated version. 

For example, the current NFPA 79 edition is dated 2012. During the update cycle we considered whether to update the Annex J Informational References for ISO 13849-1, 1990 to the more current 2006 edition. The working committee considered this change and voted to keep the 1990 edition reference for ISO 13849-1. This vote was significant because the 2006 edition would have brought into play the newer approach for the SRP/CS (Safety Related Parts of the Control System)—specifically, things like functional safety, performance levels, mean time to fail dangerous, diagnostics coverage, B10 values, and more. This is a major change.

Quite often, when a “B” level standard makes a significant change (like NFPA 79, 2002 adopting safety PLC technology), “C” level standards may or may not be reconciled and/or in sync regarding how safety circuits “shall” be designed. So, the question is asked: Which safety circuit design is required? I understand that in Europe under the Machinery Directive only current editions of standards are “listed” as required for compliance. In the U.S. OSHA is the law and consensus standards are an additional level of compliance requirements. Therefore, and in my experience, most “best-in-class” companies in the U.S. default to a current safety circuit design regardless of “B” versus “C” level standards. How has this question been answered in your experiences?

Add your comments, thoughts, questions, or suggestions about level of machine standards or related topics by submitting your observations, ideas, experiences, and challenges in the comments section below.

www.controleng.com/blogs under Machine Safety has related machine safety explanations. See specific links below.

Related articles:

Machine Safety: what is the value of ISO 13849-1 for U.S. domestic compliance?

How to use ISO functional safety standards

Machine safety standard merger: One global machine safety standard

Machine Safety: Domestic U.S. versus international standards

EHS Today: The Buzz About ISO 13849-1: The Good, the Bad and the Ugly (and a Possible Alternate Solution) by Mike Carlson

Contact: www.jbtitus.com for “Solutions for Machine Safety.”



No comments
The Top Plant program honors outstanding manufacturing facilities in North America. View the 2015 Top Plant.
The Product of the Year program recognizes products newly released in the manufacturing industries.
The Engineering Leaders Under 40 program identifies and gives recognition to young engineers who...
2016 Engineering Leaders Under 40; Future vision: Where is manufacturing headed?; Electrical distribution, redefined
Strategic outsourcing delivers efficiency; Sleeve bearing clearance; Causes of water hammer; Improve air quality; Maintenance safety; GAMS preview
World-class maintenance: The three keys to success - Deploy people, process and technology; 2016 Lubrication Guide; Why hydraulic systems get hot
Flexible offshore fire protection; Big Data's impact on operations; Bridging the skills gap; Identifying security risks
The digital oilfield: Utilizing Big Data can yield big savings; Virtualization a real solution; Tracking SIS performance
Getting to the bottom of subsea repairs: Older pipelines need more attention, and operators need a repair strategy; OTC preview; Offshore production difficult - and crucial
Applying network redundancy; Overcoming loop tuning challenges; PID control and networks
Driving motor efficiency; Preventing arc flash in mission critical facilities; Integrating alternative power and existing electrical systems
Package boilers; Natural gas infrared heating; Thermal treasure; Standby generation; Natural gas supports green efforts

Annual Salary Survey

Before the calendar turned, 2016 already had the makings of a pivotal year for manufacturing, and for the world.

There were the big events for the year, including the United States as Partner Country at Hannover Messe in April and the 2016 International Manufacturing Technology Show in Chicago in September. There's also the matter of the U.S. presidential elections in November, which promise to shape policy in manufacturing for years to come.

But the year started with global economic turmoil, as a slowdown in Chinese manufacturing triggered a worldwide stock hiccup that sent values plummeting. The continued plunge in world oil prices has resulted in a slowdown in exploration and, by extension, the manufacture of exploration equipment.

Read more: 2015 Salary Survey

Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
The One Voice for Manufacturing blog reports on federal public policy issues impacting the manufacturing sector. One Voice is a joint effort by the National Tooling and Machining...
The Society for Maintenance and Reliability Professionals an organization devoted...
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.
This article collection contains several articles on the vital role that compressed air plays in manufacturing plants.
This article collection contains several articles on the Industrial Internet of Things (IIoT) and how it is transforming manufacturing.
This article collection contains several articles on strategic maintenance and understanding all the parts of your plant.
click me