Machinery Safety 101

Ontario OHSA turns 43

The Ontario Occupational Health and Safety Act (OHSA) turns 43 today. For many workers, this important legislation came into force long before they were born, but some workers will remember the days before this important Act came into force. The Act came into force in 1979, but Ontario had a long history of labour-safety-related workplace…

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Understanding Safety Functions: the start/restart function

Car engine start/stop button

After the safety-related stopping and the reset functions, the start/restart function is the next most common. Without a start/restart function, there is no way to make the machine do what it’s supposed to do. If you’re designing a machine control system, you need to understand this function.

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Understanding Safety Functions: the Safety-related stop function

A stop sign - A red octagon with a white border, and white block text reading STOP.

The most used safety function on machinery is the safety-related stop function. The requirements discussed in this post are not generally applicable to process-related stop functions unless the process and safety stop functions share the same control system hardware and software. Copyright secured by Digiprove © 2021Acknowledgements: ISOSome Rights ReservedOriginal content here is published under these license terms: X License Type:Non-commercial, Attribution, Share…

Manual reset using an HMI

A Siemens HMI displaying control functions and data.

Question: Can a safety-related stop function, for example, be reset via a graphical object representing a reset button on an HMI? The short answer: No, with an exception. Read on if you’d like to know more. If you’re interested in knowing more about the manual reset function, see our previous post on the manual reset…

Understanding safety functions: Manual Reset

A reset button graphic

Following the risk assessment, risk reduction is the next step. Whenever the control system is called upon to reduce the risk, a safety function is needed. Safety functions are defined in safety requirement specifications. ISO 13849-1:2015 [1] offers descriptions of some of the more common safety functions. One of the most poorly understood is the…

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