Integrated Machine Safety – or Not!
How will the 2011 updated NFPA 79, Electrical Standard for Industrial Machinery, affect arguments for and against a fully integrated architecture for safety and general control?
We’ve all heard lots of arguments both for and against a fully integrated architecture for safety and general control. In the process world they’ve maintained a separate SIS (Safety Instrumented System) solution for safety creating a separate layer in their architecture for performing the safety functions. However, in the machine world when PLCs were introduced in the 1970’s, standards groups rushed to exclude PLCs from anything safety because the early technology wasn’t very reliable. Guess what happened?
Right, “anything safety” had to be hard wired relegating the safety functions to a separate layer and typically electromechanical devices. This is how the machinery world continued to live for thirty years until 2002 when NFPA 79 changed allowing hardware / software devices designed, tested, and listed for safety applications. This change in the standard opened the door for options in technology, engineering, and design. And, most importantly, the door opened for the option to integrate safety during the design phase vs adding safety to a machine usually on the plant floor. This new option to integrate safety allows machine safety technology and functions to join the rest of the architecture and enjoy all of the time tested efficiencies and cost savings brought by the innovation of machine control technology. Hard guards, hard wiring, and interfaced devices are now just an option, not the norm!
So, should I integrate machine safety or not?
To answer this question, I recommend that you evaluate your application and consider your options. Evaluate your risk assessment, the identified hazards, and what’s required to mitigate the identified hazards to tolerable levels per the industrial standards and regulations. Does your current approach to machine safety result in nuisance or intermittent machine down time? Are you getting diagnostics from your safety controls or machine guards? Do you need to reduce costs and improve productivity? Check out the related articles below because “layered” safety and “integrated” safety are now options for you to consider along with your company’s safety policy, manufacturing objectives, and business model.
INTEGRATED SAFETY COULD BE YOUR OPPORTUNITY – CONSIDER IT!
As a side note – The 2011 updated NFPA 79, Electrical Standard for Industrial Machinery, was previously expected for release this month. The schedule was recently modified and the current expected release date is June, 2011.
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