24v relay circuit - elp!

[wade88]

Ok, i personally don't feel an E stop is essential, as the hopper will be mesh guarded and there is no way am operator could get any body part into the screw feed anyway, i just assumed from what i had read it was law to have one.

I need to check up on the legal requirements of such things this afternoon, but that was the impression i have gotten.

I am having all this gear sent back today anyway and will re-purchase more relevant equipment.

I need to start this whole process again on a clean sheet.

 

[Knobhead]

 

[plugsandsparks]

Struggling to understand why, with such a major modification to this machine that the manufacturer or whoever is the machine designer has not provided the necessary documented electrical , mechanical and safety systems. Its been law for quite a while so would expect machine builders to be used to it by now.
Sure its no sweat to get a machine to start and stop / reverse under push button and plc command but that is about 10% of what has to be covered.
Dont really understand the human risk of injury on this type of plant so not going to try and add anything meaningful but just perplexed as to why its down to the site electrician to "come up with something that works"
BTW - i do find it hard to believe its not possible to get injured by this machine.

 

[Spoon]

BTW - i do find it hard to believe its not possible to get injured by this machine.

It is possible. If you read post 51 "as the hopper will be mesh guarded and there is no way an operator could get any body part into the screw feed".
Other industries use mesh guards for mixers, so you just dump your mix through the mesh and the operator can't get to any moving parts, therefore removing possible injury.

 

[wade88]

It shouldn't be my job to do this no. It's been a point of contention since i first received the email because 1) it just shouldn't be down to me to do such things after we have paid out over £250k for the whole system, and all aspects of the process should be covered 2) clearly i don't have the knowledge to carry out such work making it dangerous.

This is why i have written back and said i will not be making any modifications myself until a colleague of mine from another firm with 15 years more experience is on site to assist me.

So, it's not so much a problem anymore. I was panicked to begin with as i was being pressured by just about every bugger going to get it working and find a solution in under 72 hours and frankly didn't know what i was doing but as has been highlighted, its just not worth the jail time or potential injury for the sake of getting "the job done".

I understand my limitations and won't be prepared to the cross the border into dangerous working practices. I'm borderline enough as it is lol

 

[wade88]

 

[plugsandsparks]

OK, understand, might be worth getting the plc programme off for the relevant output that you want to stop or inhibit the starter. Just to make sure its simply an inhibit and not something else as well. Also you will need to know what output it is on
What happens if the plc inhibit fails to inhibit, is it just a messy pile or will the doors blow off... )

 

[wade88]

Wouldnt make a difference if the PLC programme failed anyway. The PLC involvement in this process in my opinion is totally redundant. It has complicated this entire issue.

Basically the auger will be manually loaded with a known amount of dry materials, (biscuit mix) by an operator. When he has loaded the exact amount in, the load cells should register the correct weight and turn the auger off. Why we need this process to be automatic is beyond me, whats wrong with just pressing stop?!

So even if the PLC fails to inhibit the aguer, the screw feed will just keep turning without any material in it. So its a total waste of time to be honest. But their engineers who have designed the machine and written the PLC sequences believe its important and beneficial to have this automatic PLC involvement.

I however, am not at all convinced. Trying to remove the human element and replace it with a PLC is just asking for trouble.

 

[Spoon]

Im feeling like Whinnie-the-Pooh this morning "a bear of very little brain" so am I right in that the idea of this project is that:
Someone loads the auger with a known amount of mix, then the operator manually start the auger. The auger moves the mix up and into the ribbon mixer. The ribbon mixer has load cells on it and when they register the correct weight then the auger stops feeding the mix. (using a PLC signal). Is that how its meant to work?

 

[Knobhead]

It is possible. If you read post 51 "as the hopper will be mesh guarded and there is no way an operator could get any body part into the screw feed".
Other industries use mesh guards for mixers, so you just dump your mix through the mesh and the operator can't get to any moving parts, therefore removing possible injury.

I spent 25 Years in quarrying, mesh gaurds are no barrier to a plant opperator. One guys head was crushed by the bar he was poking through a mesh gaurd. It doesn't need to be a body part.

 

[wade88]

Im feeling like Whinnie-the-Pooh this morning "a bear of very little brain" so am I right in that the idea of this project is that:
Someone loads the auger with a known amount of mix, then the operator manually start the auger. The auger moves the mix up and into the ribbon mixer. The ribbon mixer has load cells on it and when they register the correct weight then the auger stops feeding the mix. (using a PLC signal). Is that how its meant to work?

That is most correct Spoon yes.

 

[Spoon]

I spent 25 Years in quarrying, mesh gaurds are no barrier to a plant opperator. One guys head was crushed by the bar he was poking through a mesh gaurd. It doesn't need to be a body part.

I don't know the circumstance but shouldn't the guy know better not to be pushing a bar through the mesh in the first place. People should use their common sense.

 

[Spoon]

That is most correct Spoon yes.

Doesnt the ribbon mixer have its own motor? How is that operated? I dont know a lot about augers but isnt it the case of, if you dump 200lb of mix in it will move 200lb of mix into the mixer? Why the load cells?

 

[wade88]

Doesnt the ribbon mixer have its own motor? How is that operated? I dont know a lot about augers but isnt it the case of, if you dump 200lb of mix in it will move 200lb of mix into the mixer? Why the load cells?

Really hitting that nail on the head today Spoony. Exactly my point all along. Load cells are not needed, if nothing else useful for digital read out to see what weight is in the mixer, but PLC involvement, is like using a robot to wipe your crack clean. Novel..... but you'll do a much better job on your own.

 

[Spoon]

Really hitting that nail on the head today Spoony.

Sometimes I astound myself. I can get things right...contrary to what my missus says..

 

[wade88]

It's a females prerogative to suggest we did things wrongly, we just did things a better way to how they first planned it.

 

[Knobhead]

I don't know the circumstance but shouldn't the guy know better not to be pushing a bar through the mesh in the first place. People should use their common sense.

After 40 years of doing plant control I’ve found something out. You can’t design out STUPID!
Another thing to bear in mind. The plant operator is far more ingenious than you ever thought you were.

 

[Knobhead]

BTW I have a dim view of plant opperators.

And people that think it's "just a simple job". They never think about things.

 

[wade88]

Can only take such precautions so far though. Do everything that is reasonably practical to defray the instance of danger to a person. If an operator wants to stick a bar through the mesh, then

a) he/she deserves the repercussions for being a total plank.
b) your right, you can't design against stupid, therefore everything else you have covered is fine, the stupid people will soon die out and Darwin will have his say
c) If immediate risk has been dealt with and the only way to cause serious harm is by an operator trying to hurt themselves, then.... there really is no other solution is there.

On this particular machine operation, the operator would have to reach into a hopper, first of all squeezing their hand through 1inch steel mesh, reach the depth of the hopper which is greater than average arms length, and then tickle the auger screw or wedge their hand in it. It would take a whole new breed of stupid, to do this.

 

[C&H]

i've met some rare quarry operators, one of them had a start button jammed in with bit a bit of wire last week. heard of another one who kept coming in bandages on his hand. he tried to stop the rocks spilling from the crusher, every time he tried to push one back in another landed on top of his hand lol

 

[wade88]

Such people don't deserve hands, they should be sent to Alaska to chew the bark off trees for a living.

 

[SheffSimon]

Can only take such precautions so far though. Do everything that is reasonably practical to defray the instance of danger to a person. If an operator wants to stick a bar through the mesh, then

a) he/she deserves the repercussions for being a total plank.
b) your right, you can't design against stupid, therefore everything else you have covered is fine, the stupid people will soon die out and Darwin will have his say
c) If immediate risk has been dealt with and the only way to cause serious harm is by an operator trying to hurt themselves, then.... there really is no other solution is there.

On this particular machine operation, the operator would have to reach into a hopper, first of all squeezing their hand through 1inch steel mesh, reach the depth of the hopper which is greater than average arms length, and then tickle the auger screw or wedge their hand in it. It would take a whole new breed of stupid, to do this.

So when somebody has been injured or killed and you or your employer is in court, are you going to produce a printout of this forum thread as evidence of your risk assessment etc etc etc???

Dont get caught up in some of the b******* being spouted on here. It might be a simple machine, it might not require a PLC, whatever. All of that is irrelevant. Either do the design correctly or dont do it at all. Just bear in mind that we are talking about peoples health and wellbeing, so take it seriously or let somebody else do it. Would you like to work on equipment that hasnt been designed correctly. Doubt it.

 

[plugsandsparks]

I guess once you have come across a few accidents, some nasty, some bizarre, you will take a different view. I am currently modifying some machines for two handed operation after nearly 20 odd years of being in service. Also be looking at light curtains to stop even remote possibility of a very small human getting into a machine. My view, FWIW, if its possible to get injured, design it out.
Operator intelligence etc is simply not relevant.
Also depending on your risk assessment you may want to look at what happenes under fault conditions of any part of the machine and control system.
Its a whole new world...... (well has been for a while lol )

 

[plugsandsparks]

After a really nasty accident, nothing to do with the operator do his job, i needed to sign off a reciprocating press. Operator very lucky to live
http://www.hse.gov.uk/pubns/indg375.pdf

Is a good read.......

 

[wade88]

So when somebody has been injured or killed and you or your employer is in court, are you going to produce a printout of this forum thread as evidence of your risk assessment etc etc etc???

Dont get caught up in some of the b******* being spouted on here. It might be a simple machine, it might not require a PLC, whatever. All of that is irrelevant. Either do the design correctly or dont do it at all. Just bear in mind that we are talking about peoples health and wellbeing, so take it seriously or let somebody else do it. Would you like to work on equipment that hasnt been designed correctly. Doubt it.

Ok Simon,

I officially invite you to the premises at which I work, with your note pad and high viz on to come and carry out another risk assessment against this machine and its operation. And you will come to resounding conclusion, that there is no more that can be done to it, short of putting it inside a vacuum and the operator stands 20ft back and throws the material at it... that can make it any safer.

The concern currently is not with the auger, it is simply an auger that material is fed into, like thousands currently used in manufacture around the world, the concern lies with the electrical integration into an existing system. This is being looked at tomorrow.

Before you spout off any concern for death and court cases, there is no more design that can be done on this auger. Man stands at the end of it, man applies sack of grain, man walks away in tact.

I am taking this all seriously, but seriously, we are not talking about the handling of uranium 235 here.

 

[wade88]

this is almost identical to the auger we have for this process, with a steel mesh guard and sunken screw. You just cannot get any body part inside the auger. You would have to cut away the mesh guard and lean into it.

 

[Knobhead]

Wade, will you please accept you are out of you're depth. You've had good advice but you are totally blind to it.

 

[wade88]

I have accepted i am out of my depth!! How many times! I'm not touching a thing lol.

Jesus have mercy.

You have good eye balls, read the past posts. I have taken all advice on board, and said thank you to boot. I made a large point of thanking everyone for their advice and havent disregarded any of it!

I highlighted i was out of my depth in post 1 lol. Otherwise wouldnt have bothered going through this whole episode in the first place would I. Hardly sit around on here getting told to stew in it for fun now do I. But there is only so much "constructive criticism" that can be handed out, when people are sat at home speculating on variables and situations they are imagine are present or not.

 

[silva.foxx]

... But there is only so much "constructive criticism" that can be handed out, when people are sat at home speculating on variables and situations they are imagine are present or not.

You stated in post #1: My question is, and i appreciate the incredible vagueness of what i am asking here: -


and in post #5 you stated that no risk assessments had been done.

Forum members who are freely trying to keep you out of the sh!te and offer their valuable guidance gratis are merely pointing out the pitfalls, from what can only be imagined from your take on the situation you are in! Do not be naive to the dangers of "simplistic" machines.

Constructive Criticism is progress (and gladly taken over negative anyday). Sit back, absorb and you will benefit.

​

 

[SheffSimon]

Ok Simon,

I officially invite you to the premises at which I work, with your note pad and high viz on to come and carry out another risk assessment against this machine and its operation. And you will come to resounding conclusion, that there is no more that can be done to it, short of putting it inside a vacuum and the operator stands 20ft back and throws the material at it... that can make it any safer.

The concern currently is not with the auger, it is simply an auger that material is fed into, like thousands currently used in manufacture around the world, the concern lies with the electrical integration into an existing system. This is being looked at tomorrow.

Before you spout off any concern for death and court cases, there is no more design that can be done on this auger. Man stands at the end of it, man applies sack of grain, man walks away in tact.

I am taking this all seriously, but seriously, we are not talking about the handling of uranium 235 here.

Your glib replies about hi-viz and notepad, and uranium 235 tells us all we need to know about what you think of the advice we have tried to offer.

I'm done.

 

[Spoon]

I thought initially that wade was not listening to any advice from us, but in his defence (not that the bloke can't defend himself) if you read post 55 he is now getting a colleague to do all the risk assessments and he will just be helping his colleague out and learning from him.

 

[wade88]

Thanks Spoon I appreciate the clarification, and your right, i am perfectly capable of defending myself should i have any need to defend myself which in this case, entirely not.

I made a facetious comment because having sat there and accused me of ignoring advice and not taking on board what had been said, clearly you failed to understand any of the earlier discussion whereby i had clearly pointed out i will not be doing the work and merely assisting yet you continued to suggest i was just blundering on regardless.

Silva, i don't understand why the impression has been given that i have been ungrateful in any advice received, its quite the contrary. I am never and have never been ungrateful when receiving advice whether it be criticism or suggestion, and i certainly havent in this thread. Nor have i disregarded anyone's suggestions. I clearly made point of saying how i understand my limitations and will be backing away from this job.

I don't understand, or appreciate, the hostility just because some of you feel you are being ignored. Read it all back. No where have i made any comment that would implicate me to not appreciate or take on board any advice.

Anyway, the circuit is now explained to me, i understand how it works, how to wire it, and most important the reasons behind why certain steps need to be taken and where.

Thank you all again for the input, i don't want to leave this thread with bad tastes in people's mouths at all. I can only apologise if i have offended anyone or people feel i have been ungrateful. I trust you it is quite the polar opposite.

Ben

 

[silva.foxx]

...

Silva, i don't understand why the impression has been given that i have been ungrateful in any advice received, its quite the contrary. I am never and have never been ungrateful when receiving advice whether it be criticism or suggestion, and i certainly havent in this thread. Nor have i disregarded anyone's suggestions. I clearly made point of saying how i understand my limitations and will be backing away from this job.

I don't understand, or appreciate, the hostility just because some of you feel you are being ignored. Read it all back. No where have i made any comment that would implicate me to not appreciate or take on board any advice.

I never stated (nor did I intend to imply) that you were ungrateful. I merely pointed at that people, whom may usually charge for H&S advice, have offered it for nowt in an attempt to help. These people can only envisage what you have in front of you from your posts. These guys can not see your machine but are trying to open your mind to the traps of machinery safety. You will notice that 'consultants' on here will always point you in the right direction of legislation and law but will not spoonfeed you with all details. Solicitors do the same then charge you for the follow-up knowledge. Other guys will be offering their "real world" examples from their day-to-day work in the same vein as yourself, as controls/maintenance guys, in empathy of the situation you are in. We've all made mistakes. Perhaps big ones. This all leads to experience, which is to understand when you've made the same c0ck-up twice.

Hostility... or genuine concern in helping you. Nobody wants you to fail. Nobody wants you to get hurt. Everybody wants you to keep all fingers intact to continue your valued input and wacky ideas.

This site is all about offering a certain type of help... and not a noose or stoning.

So chin up. Bring on your next project so we can batter you on a new topic.