PLC Control and Stop, not E-Stop, buttons

[PeterW]

Which is why safety should not be software but hardware (hard wired E-Stops that remove motive power).

 

[muttleydoo]

Exactly my point you can't control safety using plc logic. As long as the machine has got sound safety systems i.e. complying e-stop and safety gates and the machine comes to a halt if the guards are open then "it is safe" it doesn't matter that the stop button need to be constantly depressed to pause the machine. Maybe it needs to be re-labelled as pause. A thorough risk assessment would tell the story.

 

[leitmotif]

All machines have stop buttons, and this machine has an unsafe one. If this machinery is capable of causing injury, then its wrong. You can go to court to defend your non-action, or you can fix it as soon as possible. Send your boss an email outlining the violations to CYA, then it's on them, but for the sake of the actual fingertips involved, hang your freaking padlock on the machine and tell it's going to be down for an hour, and when you power it back up, explain how the new reset button works.

What are they going to do, make you put it back? Refuse.

I have been in this situation, and kept a machine down over 24 hours. It didn't harm my career at all.

And if it had then getting fired would be the equivalent of a doctor curing your gonorhea.

Dan Bentler

 

[Stephen3776]

Muttleydoo,

The only way to stop oany of the emachines is with the stop button or the PLC programming. In addition, resetting any E-Stop will restart the machine the E-Stop is preventing from running. I can see so sound safegaurds or I am a overly concerned with safe operation.
Did I mention that when I initially inquired about NFPA 79 regulations that I got the "deer in the headlights look" and a not sure if the NFPA 79 Standards apply to the chemical industry response.

 

[muttleydoo]

I should have mentioned that it's always good to stop any machinery before the guards are opened to prevent any problems with restarting. So for the sake of that alone I would give the machine a proper stop function.

 

[cwal61]

Take a look at this it may give some information on your situation

 

[OkiePC]

Nice link. Thanks.