Local Control Station / E-Stop Requirement

[Histor]

Could anyone please help me in determining the E-stop requirement for Rotary Valves, Screw feeder and Conveyor motors?

I've never seen a field E-Stop / Local Control station for these in my past. But in my current Project, Process engineer assumed that we need field E-stop for these motors. He was not sure. Please help me with your recommendations. Thanks in advance.

 

[jraef]

From an ELECTRICAL / Code standpoint, there is no requirement for having an E-Stop on anything (here in North America anyway). It's strictly a user decision.

From a SAFETY standpoint, that's up to the Safety Evaluation, which takes a lot of other aspects into the decision.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[itsmoked]

a lot of other aspects into the decision

Like fundamentally, can anyone's clothes, fingers, or other body parts EVER get caught in these conveyors? Can the product on the conveyor ever get unintentionally clogged, blocked, misguided, or diverted? If yes to any of these it would behoove the system to have easily accessible E-STOPs available. If these conveyors run horizontally to the floor/ground then a cable E-STOP becomes more appropriate so the E-STOP mechanism can be operated from anywhere near the entire conveyor.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[FacEngrPE]

See the "ASME B20.1-2021: Safety Standard For Conveyors And Related Equipment", OSHA may involk this by reference.
See also the "General Duty Clause"

https://www.osha.gov/laws-regs/standardinterpretations/2003-12-18-1[/URL]]
Employers can be cited for violation of the General Duty Clause if a recognized serious hazard exists in their workplace and the employer does not take reasonable steps to prevent or abate the hazard. The General Duty Clause is used only where there is no standard that applies to the particular hazard. The following elements are necessary to prove a violation of the General Duty Clause:
[ul]
[li]The employer failed to keep the workplace free of a hazard to which employees of that employer were exposed;[/li]
[li]The hazard was recognized;[/li]
[li]The hazard was causing or was likely to cause death orserious physical harm; and[/li]
[li]There was a feasible and useful method to correct the hazard.[/li]
[/ul]

 

[BrianPetersen]

Check locally-applicable regulations and standards.

There ought to be a "stop", or "emergency-stop", adjacent to any "start".

There may be other places where an operator could be expected to want to stop a machine. In many cases, for open conveyors, this could be alongside any accessible length of the conveyor - in which case, pull-cord emergency-stops can make a lot of sense.

If the apparatus that you are talking about is fully enclosed in a bolted-together enclosure then that is a guarding situation, not necessarily an emergency-stop situation. (Rotary valves are probably like this)

If the apparatus has a hinged or otherwise easily-opened access cover then you are getting into interlocking, and you need to think long and hard about the suitability and integrity of everything in the interlock system. ISO 13849-1 may be applicable. Be careful, this needs to be done properly.

 

[Histor]

Thank you so much for sharing your knowledge

 

[JezNZ]

Everything above, if in the IEC world, you probably want to be looking at IEC/EN 62061