E-stop cover?

[Larf03]

I've just got the strangest request by one of my clients: COver the E-stop.

While he does not give any specific requirements, he insists that the E-stop should be covered and personnaly, I think it's pretty strange and it defeats the purpose of an e-stop.

Do you guys know any article or laws that I could use to dissuade him ??? I'm I even allowed to do that? I bet I'm not...

I'm pretty confused over this so any help is most appreciated!!

Thanks!

Fred

 

[EEJaime]

Maybe it's just me, but I have no idea what an "E-stop" is.

 

[ScottyUK]

Emergency stop button. ESD button. Etc.


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Sometimes I only open my mouth to swap feet...

 

[dinkelja]

What type of equipment does it deactivate?

 

[KENAT]

Where is the equipment located &/or where are you building it.

This would effect which rules are in effect.

 

[BJC]

Most of the E-stop buttons I have seen have covers available from the manufacturer ( SquareD, Allen Bradley Etc.) Some "E-Stops" even have break-glass covers.
The question has to be answered in the context of the equipment and the operating envornment. Is someone likely to become entangled in the machine and is an immediate stop required? If the additional time required to lift a cover, or break some glass could mean injury ( additional harm or injury ) then don't do it.
You could tell the owner where to buy one but i wouldn't even document that.
I ahve seen E-Stops that were in the wrong place and got bumped or for some reason caused a lot of nussiance tripping. Some owner think the way to fix that problem is to cover the button. If that's what your client is doing help him out to the point of being an accessory in getting someone hurt or killed. There are standards and requirements for estops.

 

[RonShap]

http://www.sti-usa.com/

 

[jpankask]

If you can post some more details of the application, you can probably get some more and direct input. I have seen a lot of E-stops that have a flip-up type cover, when the application is not too critical. Perhaps, simply moving the E-stop would be a better solution, to a more overhead position where it won't get bumped as easy. I'm going to guess that is what your client is trying to prevent, nuisance shutting off of his equipment. In some cases, an accidental E-stop could cost a lot of money or damaged product, or possibly an even more dangerous situation. Of course, that cost is nothing compared to someone's life or limbs but two or three costly accidental trips with the bottom line affected and the plant manager or corporate office is going to come down on someone.

 

[waross]

A possible compromise that may be safer:
Use a button with a raised ring surounding it. This is still a one handed, one step, operation but the button must be pushed with a finger and it has some protection from being operated by an inadvertent bump.
A cover makes it a two step operation.
respectfully

 

[dpc]

All emergency stop buttons are not created equal. If it's life safety related, I don't the covers are going to be acceptable to OSHA.

If it's an emergency shutdown button on boiler or turbine, I don't see a problem with the cover. Guarded pushbuttons are often used instead of covers.

It is common to require that TWO pushbutttons be pushed for boiler trips and turbine trips. One plant I worked at had two PBs from emergency boiler trip. One was labeled "TRIP", the other was labeled "THINK".

 

[KENAT]

Waross beat me to it, some kind of guarded E Stop may be better,

If you can't find one with a 'ring' around it then putting a separate guard around it may work. Either something in sheet metal or a couple of 'U' shapes, one either side, made from rod (some kinds of draw/door handles would work) might be adequate.

I've actually hit the E stop button on a tool by accident, it was back in a summer job at uni. I was cleaning the room and moved a chair out of the way and the chair hit the E stop. The tool was already off but I think hitting the E stop moved it to some default 'safe' position and being pneumatically driven it made a terrible hiss and I nearly wet myself!

I'd still try and find the relevant legal standards though.

 

[EEJaime]

I don't know why that didn't register. Waross' raised ring type are very good, but also the flip covers are easy to use one-handed and provide protection from dropped tools, etc.... Some of our clients prefer the large mushroom type buttons where they can be mounted out of normal working traffic paths to avoid accidental activation. We used them on a Generator plant Emergency stop and in the same plant on the refrigerant leak detection and purge system.

 

[jraef]

As an example, Siemens offers a shroud specifically for E-stop buttons. Not sure if this link will work though...

Siemens 3SB3921-0AK

 

[FreddyNurk]

There are some options that I've used on other installs, some appeared to work better than others. One type routinely specified, with much the same client specification, was a recessed E-Stop button, where a large ~100mm dome was recessed into the panel, and a standard 22mm mushroom button used. If placed in the wrong spot, they still didn't prevent people from leaning on them, though they were a great improvement over a protruding E-Stop. I don't know who manufactured these.

Also, Sprecher & Schuh make collars that fit around their 22mm E-Stop mushrooms. Doesn't stop the protrusion out of the panel, does make it that much harder to accidentally press, and it will still activate if belted with the palm of your hand. I left the company before I received any client feedback on this type of arrangement. I'm sure that other manufacturers will have similar.

As others have said, if its a safety issue, I'd not want to be installing it. We actually used the recessed version on one system as the client insisted that we cover it, and we refused.

 

[Larf03]

Thanks a lot everyone,

I've got enough hints to submit something to my client. I thought E-Stops were more strict than that. FYI, My application does not present risks of mutilation, strangulation.

Thanks

 

[dw51]

The latest NFPA 79 (if we might be discussing Industrial Machinery) leaves some room for interpretation. It says both Emergency Stop and Emergency Switching Off - note two separate definitions, require a single human action to initiate. But under Emergency Switching Off they specifically permit a break glass cover, an option they do not offer for Emergency Stop.

I have frequently seen the requirement for a 'palm operated device' to preclude the cover or excessively tall rings or barriers around e-stops. I requested a clarification from NFPA in a data center years ago and was given a formal interpretation at that time that covers or excessive barriers around e-stops defeated the intent of the function and were not permitted. I have not seen a break glass switch listed by an NRTL for Emergency use. May be out there, I just haven't seen it yet.

Good Luck