Emergency Stop - A Bit of a Complaint

Don't worry it will soon all be done by robots...

Yeah - but how we going to stop the Terminator's "Judgement Day" before it starts if we don't have E-Stop buttons we can push in a big hurry?

As you may recall at the very end of Terminator 3: Rise of the Machines, as John Connor waxes morbid about the inevitability of Judgement Day, we see SkyNet nuking itself senseless. Why? Because those robots couldn't get their mitts on the E.S. button and, apparently, neither could producer James Cameron.

I agree, the old-style recessed button makes a lot more sense. When you think about it, that's sort of what they're doing now the hard way: recessing it behind/inside a cage.

You just wait: some hipster-type will spot an old-style recessed button in his granddad's yellowed, 1967 copy of Allied Radio Industrial Catalog, put forth the idea to his boss as his own stroke of genius, get promoted to managment for 'thinking-up' something that has been around since Christ was a colonel, and the circle is complete.

Until the next generation of safety engineers decides it needs a cage.

No prankster. Just your usual Safety Department saying we need fast emergency stopping versus the Production Department saying we can't afford to ever lose a batch if that danged E-Stop gets tripped mid production run. I have had to do this for several customers and I wonder how they got this past OSHA, to allow production of such a cage in the first place. Or, is OSHA conflicting within on the issue?

Well this panel has been through a UL 508A inspection, but they don't really get into that end of safety. If it is outside the panel - it is not important in a 508A inspection. Not much I can do here, without costing our company a customer. This, and the others I've worked on, is a process skid control panel for a third party, who ultimately was the one issuing the spec calling for this device. In this case, we didn't even build the panel here, as some customer's have them built by other shops. We will simply install it and wire our instruments and motors to it. No - I have to stay out of this. I just like to rant about the seeming incongruity of the combination of devices and wonder how this cage device, of which there are several variations commercially available, even came to be developed in the first place, without some safety regulating body going ballistic.

I am all for safety but i have had arguments with the safety department. They sometimes have no practical view of what is effective(just move the building over 1 foot 3 inches) To have an effective solution sometimes an E stop was not a plunge switch but a tension line with handles hanging from the line which the operator had to reach up and pull.

..."According to international standards,the emergency stop function must be initiated by a single human action using a manually actuated control device. The E-Stop function must be operational at all times and designed to stop the machine without creating additional hazards."...

..."Depending on design and application requirements, many E-Stops are listed as UL category NISD emergency stop devices.This rating covers two categories of E-Stop function as defined in ANSI/NFPA 79, Electrical Standards for Industrial Machinery (ANSI is the American National Standards Institute and NFPA is the National Fire Protection Association):

1. Stop Category 0 – Immediate removal of power to the machine or mechanical disconnection (de-clutching) of hazardous elements.

2. Stop Category 1 – Controlled stop with power available to stop the machine followed by removal of power when the stop is achieved. The emergency stop actuator provided in these devices must be a self-latching type. E-Stops with this rating have been reviewed for their functionality in addition to fire and electric shock safety."...

http://www.newark.com/pdfs/techarticles/eao/EAO_Emergency_Stops-What_Designers_Need_to_Know.pdf

Well the E-Stop switch and surrounding wall or cage definitely meets those rather loose definitions, but still looks like an after thought and a compromise. Notice in the referenced article, there are no pictures, nor mention of a protective shield around the button to limit access to directly from in front of the switch. By the way, on a side note, the main power switch if in red and yellow and appropriately marked can be used a an emergency stop, if killing all power is acceptable. That would be a bit easier than zeroing in on this E-Stop button inside a surrounding device. Perhaps that comment in the article about not creating an additional hazard is the justification for the protective surround.

By the way - there is a Category 3 which we often have to meet for European companies, involving multiple contacts on the E-Stop switch and on any controlling relay so a failure on one leaves a second set. Requires an upscale safety relay with multiple circuits to comply.

Why not position the e-stop (no cage) at about shoulder or head height? Easy enough to hit when necessary, but unlikely to be activated by accident.

Again, as stated in previous replies, this is on a panel I must install on one of our process skids that we didn't build here - the customer farmed it out to a local shop he could check on weekly without driving 275 miles.

The other situations I've encountered, we have customer specs we MUST obey, so the "cage" is a necessity, or it will be added after FAT before the customer will accept it.

It is an unwritten rule, in this industry our skids serve, that E-Stop switches are expected to be in the control panel on these skids, and head height is also HMI height. Try to mount it elsewhere and the customer will fail the drawing review. (I've tried that before)

This is not my point - my point is that we've taken a perfectly good improvement, an E-Stop switch with a large head and extended way beyond what a standard oil tight switch would be, so it is much easier to activate than a standard switch, and then added a second "improvement" to make it just like the standard oil tight switch, except it is now twice as expensive. Seems a bit stupid to me.

I see your point, and it does seem crazy to change the design to make it easier to operate, then decide it's now too easy, and add a feature to make it harder. Why not revert to the original (cheaper) design? as you suggest in original post.

Whose head or shoulders? Kareem Abdul Jabar? Mickey Rooney?

Mickey Rooney clone in the remake of DeepWater Horizon movie, Oh snap that is Marky Mark Wahlberg.

"Here let me hit that bit red e-stop button, and cut the pipe (and also activate B.O.P.)!

Oh heck, I can't reach it, so let me go to the other side of the rig and get a box to stand on....pant, pant, pant, OH SNAP, this box is too short (and so am I), where's a ladder when you need one, OH SNAP, OSHA does not allow ladders on the drill floor, or in the rig pilot room....where's that tall guy we had here about an hour ago?"

Yes, all right, I thought about adding that it must be reachable by somebody short, but it seemed too obvious. They shouldn't allow midgets on the site

Now that is able to be answered - we run into this all the time with the HMI (monitor) in panels, so it is based on the average height of the working person in the country it is going to. The middle of an HMI is about 5'-6" give or take a bit on a panel for the USA and about 6" lower for one going to China. Exceptions such as you listed are not considered. The E-Stop, if following the suggestion, would be placed similarly.

The "can't reach it" scenario would be a problem for the customer's Safety Department to handle. They no doubt have to make other concessions/compromises for such an employee. However, E-stops are not mounted at that height, so all employees, except a true dwarf or what ever the PC name is now for that term, can reach them. If a customer has such an employee. we would hope they would let us know and we could adjust for that exception to the rule.

What Production sees:

Safety: "We don' wana see people get hurt or scared! WAAA!"

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What Safety sees:

Production: "We don' wanna stop production for nuttin'! WAAA!"

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What OSHA says: "You can either loose a little production and spend a little money now; or you can lose a LOT of production, pay a big fine, and still have to pay that same little money on top of all that later. It's your choice."

OR you can just walk away, or go set up shop in a Banana Republic somewhere and then charge too much for your substandard goods in America.

At least you can until Friday, January 20, 2017, then its your posterior if you quit and walk out on us (America).

Some will fear America (and rightly so), others will merely be envious of America (and rightly so).

Safety never costs, it pays. Production with safety is its own reward, and everything then travels at Godspeed (some say this is faster than time itself).

"Safety never costs, it pays."

Preaching to the choir here, James. I'm the Team Leader for the plant's Safety Team. Unless I'm starting out my pointing out the cost of the OSHA fines for a violation, the conversation is as productive as a card-carrying Democrat and a card-carrying Republican sitting down to talk politics⁽¹⁾.

Notes:

1. This is something I generally avoid recommending, unless one is able to observe the conversation from a safe distance, say 2-3 states over.

Maybe politics should be a cage match, the loser being the one that punches the big red, e-stop button.

Trust me, I have never seen any place where injuries increase productivity or profitability.

Deaths in the immediate record, are a pretty good deterrent to finding replacement employees, unless you just want the slow ones.

I could comment more here, but it wouldn't be ... polite.

Safety first! No cage, and damn the batch/run if it's accidentally tripped!

As stated earlier - several large corporations practice this. I got burned by one of them when I had to install 4 of these cages after the FAT. They had it in their specs and I missed it. Interestingly, the ones requiring it have main offices located in Europe, which makes me wonder if this is OSHA approved? Nah - an European corporation would never try to circumvent a USA regulatory agency, would they? (Fahrvergnugen)

Sorry! I was just giving my opinion of what I think it SHOULD be. The attitude of these corporations seems to be that "operators are clumsy and stupid, therefore let's make it so the operators can't accidentally trip the e-stop like we know they will".

I don't claim to know safety regs, but this just seems wrong. I guess it also depends on whether the e-stop is meant to save someone from getting hurt or killed (which is what I was originally thinking - all the e-stops I have seen were mainly to prevent injury/death).

Think Deep Water Horizon - the people that could have pressed red E-stop (and cut the drill pipe off) could have saved lives, and the rig, and still probably have put the fire out quickly, but one threatened another not to do it (the rig pilot), and in the meantime, the people near the drill floor got wiped out and could not press it.

Nobody listened to anyone, things happened, other things did not happen. How important (or not) is this stupid cage over the E-Stop switch then? There were two (or more) locations of the E-Stop (and pipe cut), one in easy access on the drill deck (drill floor), another in the pilot room behind an easily opened glass panel.

So what your project is 30 or more days behind schedule, and so what some foreign country supposedly owns the job (not for long if they are breaking our rules).

There is no corporation big enough to overcome a law suit where they are caught red-handed, directly violating law, ignoring the protection of workers, and ignoring environmental protection (in the basic common sense ways). Ask BP how they feel about rig safety now...

"Ask BP how they feel about rig safety now..."

I think they feel they shouldn't get caught again but the how and why part of what they are doing to prevent getting caught again could be debatable.

Hilarious, but I like the way you think. Most criminals only regret being caught, not what they did.

"...but the how and why part of what they are doing to prevent getting caught again could be debatable."

The 'how and why' is probably looking something like "Contract a Jamaican holding company to sub-contract to a South Korean drilling company, which will then sub-sub-contract to a Turkish outfit, using ships and oi rigs registered out of Zimbabwe, and hiring a 'security consulting company' from Bosnia, which will be using Ukrainian PT boats of Russian manufacture to insure no vessel gets close enough to even hail the oil rig.

Only a True Democrat could conceive such a twisted plan to avert prosecution.

Of course, I do not believe that the Democrat Representatives are legitimate - the word bastages comes to mind. Not since 1860 has there been a Democrat boycott of the inauguration. Let's see, how did that work out for you in the past?

Back in 1860, the Liberals were the Republicans ("Lincoln' Lovers" was the insult of the day, or rather it was the insult of the day starting in 1861.) and the Conservatives were the Democrats.

Tsk, tsk, reaching back to the pre-LBJ era to use the Southern Racist Democrats to try and besmerch the post-LBJ Northern multi-cultural Democrats. That's just bad form. What would your great-grandfather say about such low, obvious mudslinging. Then again, he was probably a Southern Democrat all his life.

For the people (mostly non-Amaerican) who might not understand where I'm coming from with this, here's a good starting point for research: https://en.wikipedia.org/wiki/Southern_strategy

You really have no idea about my grandfather. He never offered any man other than help if it was needed, hope if he was without it, and a square deal if it was business.

Some of you folks could do with a bit of old-fashioned honesty, but that might curdle your milk.

What you need is a emergency stop switch with a cover that can be easily raised and still allow the button to be pushed with a simple motion. The cover protects against accidental bumps, but is easily flipped out of the way. Something like this.

It's missing the padlock holes.

Has anyone actually considered moving the E-Stop buttons to more suitable locations that are well within easy reach and operation by the machine operators and not so easily bumped by accident?

One of my first jobs I ever had was as a service tech at a Pasta plant and we had some new equipment installed while I was there that apparently had the E-Stop buttons placed by some fool who had never ever worked on a manufacturing line.

Literally front and center of the work areas so that the were as in the way as absolutely possible and unavoidable to trip.

Our solution was to just relocate them to the side of where the floor workers stood. still simple and easy to trip if needed and met code.

So that first one is in the left kitchen sink, and is the e-stop for the garbage disposer?

That is hilarious!

I want my e-stop button to be loud proud, and easy. 'Nuff said.

I want my e-stop button to be loud proud, and easy. Me too. I wonder what if your hands get stuck and you want/have to hit the switch with your shoulder or head?

The partial shields, still easy to hit the button in time of need, but idiot s-too-dense can't trip it by 'brushing' it as they pass are what we have for whole room/lab EPO's.

Protection against accidental activation is reasonable in most cases, if the thing is so 'potentially' dangerous a single EPO button isn't going to be enough in the first place.

An E-stop switch should be easy to hit on purpose but not easy to hit by accident. Where these requirements are contradictory, it seems that you should err on the side of safety, IMHO.

In critical process applications haven't dead man switches and sensors taken over the role of unguarded estop switches that need to be accessed as soon as possible (if not sooner to prevent injury)? A differentiation between estop for safety and estop to prevent process or equipment damage (a less urgent need to activate).

Many of the estop switches we supply with guards the guards have the facility to be lockable closed to allow the estop to be used more as an isolation method and less of an estop.

Not on process skids. The E-Stop is a required safety system, manually activated, and is often on there in multiple locations. The lock out device is the main switch on the power panel, or on individual motor feeds if the entire skid is not to be shut down, and the main air supply has a lock out capability. We have to have manually activated switches and hard wiring - we can't use the PLC in an e-stop system - that switch is hard wired to safety relay(s) that are hard wired to contactors or solenoids. Now we do have many sensors that will stop operations and flag an alarm, such as pressure burst disks wired back to the PLC, or overspeed sensors or over temperature sensors. These are not considered part of the emergency stop system, although technically they are. These are allowed to operate through the PLC.

Most of the time, to be honest, estop switch really does not care WTF what is the reason for the shut down, but the shut-down will take place nevertheless.

Just make the thing a loud color, out there in front (proud), and easy to hit on purpose. Besides that makes a good reason for slackers not to be leaning up against walls in odd places.

It's not quite that easy - the colors and the label requirements are spelled out in code.

My complaint on this one is that it isn't that easy to hit. You have to really want to hit it, while on most skids we build, a slap from any direction in the general vicinity will do. Solar Eagle pointed out that there is nothing written to suggest it has to be that way - just dedicated, accessible, and labeled.

The point of my post was to poke fun at the way we tend to over engineer things, especially when safety gets involved. The manufacturers developed a fine switch that as stated, you just needed to slap in the general direction of to activate it, an improvement over a standard oil tight switch, which you had to find and stick your fingers into it to activate. Now we have progressed on to a guard around this improved switch, so you need to try to hit with your fingers in an emergency situation, because someone thought the open extended switch just might get bumped by accident. So what we have now is no better and far more costly than a standard oil tight recessed switch, which we've had for decades. Fine progress we've made here. We moved on to a better switch, then right back to the same constraints as before, but at a higher cost.

That is the insanity within the sanity of things.

If this is a process that has a lot of stored energy, hitting the e-stop should be followed immediately by proceeding to the mustering area, for a head count. If the stored energy is large enough, pretty much bend over and kiss it goodbye.

I think of refineries where columns may have literally tons of liquid held up presently as vapor, and that wants to find a way out or to flood something and escape and catch on fire.

In a chemical plant, you not only have hot vapor, you have some reactive intermediates that will cause instantaneous death if inhaled. It just keeps on getting better from there.

That is why we have Control Engineers (let me introduce you to one - name Phys) We are to have enough sense to design the E-Stop system so that things that should not be stopped remain energized. We don't kill everything on a process skid. Usually only the motors and particular valves. Essentials, such as the PLC and monitoring remain energized. That is why we have a manual emergency stop system, otherwise it is quite legal to just tell them to hit the main switch if we have labeled it as an emergency stop.

Now in this particular job, some other control Engineer designed the system, but you can bet, as soon as I get a copy of the current electrical schematics, I'm calling up the P&ID and having a darn good review of what is being stopped. Other items will also be analyzed and I usually find at least one circuit designed wrong on this particular type of skid.

Not just the chemical industry. Decades ago an industrial drill press was shut off and the operator's sleeve got tangled in the still rotating spindle, but there was enough momentum in the shut-off machine that it ripped his arm off at the shoulder.

Yes, loose clothing is not good, and moment of inertia has killed more than one.

That is why real safe practice requires machine brakes, at least in some industrial settings.

The old story used to go, "Where's my golden arm...where's my arm golden arm...YOU TOOK IT!" (...the sounds of children screaming and scurrying for the exits.)

In this modern era, no problem, the gent goes down to the cloning station, and gets a cloned arm, not golden, but costing as much.

Everyone wants a piece of that ready. Not everyone is willing to put on that extra piece of safety and be ready.

Over the years as I have come to see it,

Only a fool thinks that intelligent people and thought are behind the design and implementation of safety rules and systems.

You got that right.

Have the company lawyers design/approve it. They know what's going to happen when the litigant tells the judge, "I tried to operate the safety switch bit my gloved hands couldn't get past the obstruction that was placed there by the manufacturer."

Fortunately, as I stated before in another reply, on this particular skid, we are only mounting the panel - others built the panel with the E-Stop switch in it. We aren't even wiring to that switch. Just to skid instruments. Heck we don't even get the wiring to the motors, as that will be done on site.

I've seen pull style switches, and I've also seen one of those triggered accidentally by an operator yanking his hat off the table before going outside. We had a client who wanted to put one out at their gate and then a contractor hit it trying to get the gate to open despite the label. You can't fix stupid sometimes. Whatever you put there, somebody will figure out a way to hit it accidentally.

And then there is the person who knows better who is in a hurry....

I was forced onto the production floor to wire a skid, and since I was the last to leave, that means I know it had to be after 2AM or it was a Sunday. Definitely a time I did not want to be there another second. Anyhow, this was the first time I had to shut down the plant air compressor, and I just hit the first red button I saw. (stop is from a touch switch on a screen) Unfortunately it had the required yellow ring label around it. You know what the button was I hit. Yes I did even though I am the one who specifies the extended red switch with yellow ring around it for the panels we build. Oops - Maintenance was a bit upset with me the next day - a restart from emergency stop is not straight forward - they had to get the manual out and read it.*

An Emergency Stop without a safety cage wouldn't be politically correct, that's why.