Safety relay/plc?

[Ned_Flanders]

I was asked at work to add a reverse button to a simple conveyor which has a stitcher (Bag closer) mounted on it and a mechanical "Kicker" for sealing 25kg sacks.

The machine supplier has fitted an e/stop button, but used the plc as a safety relay, with the "Reset" being achived within the program.

This is not any kind of safety plc, just a simple mitsubishi with 8inputs/8 outputs.

The machine is CE marked and less than 6 months old but I have flagged this up as unsafe.

Am I right?

 

[OkiePC]

Yes, you are right in my opinion.

If the machine is capable of causing injury, and that button is labelled as E-Stop, then I would be even more certain you are right.

Now if the machine is guarded so that no one can get hurt without using tools to remove the guards, perhaps it is legal...I am not an expert in this area, so I am just giving my opinion.

 

[jstolaruk]

A CE marking has nothing to do with the machine's safety strategy. A safety assessment should be done to gauge the safety risks and then corrective actions should be taken. If the machine is, as OkiePC pointed, mechanically guarded around hazardous motion, the existing scheme may be okay.

 

[Manglemender]

To issue a Declaration of Conformity the machine builder should have done a risk assessment on the machine. It may be, as others have suggested, that because of mechanical guarding that the machine poses no threat but then it shouldn't have an emergency stop button, just a "stop" button.

Ask the machine builder for a copy of their risk Assessment and Declaration of Conformity for the machine.

Nick

 

[mordred]

I agree with what the others have stated.