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Old February 14th, 2020, 08:25 PM   #16
ValeoBill
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E-stop...we don't need no stinkin' e-stops!

Let's assume that the risk assessment is complete. As long as the re-positioning of the device does not endanger a worker - out of reach etc - do whatever ya like. I worked in wired cells that were designed with master and zone e-stops to allow total or partial line shutdowns. Example: two parallel conveyors merge to feed one main. One conveyor can be safely shutdown for proactive maintenance (I'm told it DOES happen somewhere) while the main line is fed from the other. Adding a "master" e-stop - wired upstream of the cell e-stops - would not diminish the existing safety of your cell. If a risk assessment doesn't mandate it no big deal. A risk assessment is the minimum requirement.
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Old February 14th, 2020, 09:53 PM   #17
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As for running risk assessments I have heard this time and time again on this form but I have yet to ever meet an Engineer that does them or even knows anything about how to do one.
I've never met the Queen, but I'm sure she exists.

I can assure you that any engineer that designs safety circuits, not only knows about risk assessments, but indeed does do them religiously. They are the linchpin of any safety design.

It's not just a case of wacking in an e-stop or two because 'sAftee'
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Old February 15th, 2020, 09:45 AM   #18
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Originally Posted by janner_10 View Post
I've never met the Queen, but I'm sure she exists.

I can assure you that any engineer that designs safety circuits, not only knows about risk assessments, but indeed does do them religiously. They are the linchpin of any safety design.

It's not just a case of wacking in an e-stop or two because 'sAftee'
oh I know they exist but in what industries and what scale of project? I have always designed smaller machines, and yes a lot of them had safety circuits complex enough to require programmable safety controls to be practical. Yes I design them and don't do any risk assessments. I've never even been asked about risk assessment by customers or anyone else outside this forum.

So obviously risk assessment are not done every time a safety circuit is designed.

Where do I learn about risk assessment and how to do one? I not opposed to learning. I'm just opposed to people telling me things are universally true when they are not.
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Old February 15th, 2020, 12:58 PM   #19
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oh I know they exist but in what industries and what scale of project? I have always designed smaller machines, and yes a lot of them had safety circuits complex enough to require programmable safety controls to be practical. Yes I design them and don't do any risk assessments. I've never even been asked about risk assessment by customers or anyone else outside this forum.

So obviously risk assessment are not done every time a safety circuit is designed.

Where do I learn about risk assessment and how to do one? I not opposed to learning. I'm just opposed to people telling me things are universally true when they are not.
For the factories that we sell machines to in Ontario there are regulations that the machine must have a PHSR (Pre-Start Health Safety Review) completed by a certified engineer. This cannot be done by us because of the legal issues in getting this taken care of and who can sue who if someone gets hurt. Basically the assessor goes about the assembled machine with fancy gauges and measurements then inspects/notes down the following:
- pinch points and finger clearance in guarding
- suspended loads or stored potential energy
- robots and safety interlocks if there is any small potential of contact
- electrical schematics and how they relate to safety control
- estop safety circuits and location of buttons in respect to operators
- pneumatic/hydraulic schematics and pressure dump points (po checks and centre exhaust valves especially)
- light curtain/gate access methods
- use of “tool” to remove guarding and non-controllable items
After this, they create a report and bring forward all the findings of stuff that is deficient. Once the assessment has all the deficiencies rectified they will issue a hard-copy printed certificate. This basically holds the inspectors organization responsible and clears the OEM and customer of legal liabilities should the machine injure someone because it is “unsafe”. Any modifications after the inspection will void this which is why it always needs to be re-certified after even moving it from site to site outside the noted inspection location.

The engineer that I was working with had an open mindset as long as the application process was explained fully and all of her questions were answered. The process started out with my initial controls assessment that I made and how I designed the safety circuit based on my past experience, and then she “checked my work” against her numbered calculations she made. I had a cell the size of a shopping cart with 10 valves and an estop and it warranted a 30 page report with photos.
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Old February 15th, 2020, 01:41 PM   #20
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One thing that still amazes me about shop personnel is I have told more than one person that the red mushroom button labelled E-Stop is not a decoration to appease an OSHA inspector - they actually work and that it is pressed is why their machine will not run!

Even if the HMI says ALARM: E-STOP
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Old February 15th, 2020, 03:07 PM   #21
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oh I know they exist but in what industries and what scale of project?

In europe? My understanding is they are done for every single project for every single machine. It's a legal requirement.

In the US? They are done or required by companies who want to have legal documentation that they are at least attempting to care about their workers' safety. It's a sadly small number. Here the regulators don't REALLY check anything until someone gets hurt, and then you're usually screwed no matter what.
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Old February 15th, 2020, 08:01 PM   #22
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In europe? My understanding is they are done for every single project for every single machine. It's a legal requirement.

In the US? They are done or required by companies who want to have legal documentation that they are at least attempting to care about their workers' safety. It's a sadly small number. Here the regulators don't REALLY check anything until someone gets hurt, and then you're usually screwed no matter what.
ok this makes sense. I was having a surreal moment like, what legislation... did I wake up in a alternate reality?

I don't live or work in Canada or Europe people. Lol
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Old February 16th, 2020, 11:41 AM   #23
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I understand that the law is a little bit opposite in the US and EU when it comes to machine safety. Yes in the EU it the law, ii is part of the "Declaration of Conformity to EC Standard" which must be publicised for every machine or machine part, big or small, and must be signed by a responsible of the vendor company, the CEO or someone else high up.
In the US you dont have to declare anything, but you will be damned if an accident happens with the machine you delivered. You will be sued for liability.
In the EU, if you have done everything to the letter (which involves more than making a risk assessment or publishing a Declaration of Conformity) you are pretty much absolved from liability.


theColonel26, someone else who is better versed in US law may tell you more precisely, but if I were you I would be careful. I think there is a risk you may be personally liable if you have designed the safety on a machine without risk assessment.
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Old February 16th, 2020, 01:55 PM   #24
janner_10
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ok this makes sense. I was having a surreal moment like, what legislation... did I wake up in a alternate reality?

I don't live or work in Canada or Europe people. Lol
This is why our wires are crossed, apologies for the flippant post earlier.

In the EU, it is a very structured and documented process. But that ultimately means the regs are continent-wide. A machine built in Spain is pretty much built to the same safety standards as the machine built in Scotland.
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Old February 17th, 2020, 02:03 PM   #25
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This is why our wires are crossed, apologies for the flippant post earlier.

In the EU, it is a very structured and documented process. But that ultimately means the regs are continent-wide. A machine built in Spain is pretty much built to the same safety standards as the machine built in Scotland.

at same time in China

https://www.youtube.com/watch?v=sjNaUHA2KrY
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Old February 17th, 2020, 10:21 PM   #26
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I wish the US would adopt the PHSR same as canada. So that I can stop having to explain my designs for EVERY single machine turnkey i do.

"Why do we need this?"
"Why isn't a single pole limit switch thats wired into the standard PLC input OK for that door that opens the operator up to a 10,000 RPM spindle turning a 5 inch cutter, flinging razor sharp pieces or metal all over the place?"

When we do jobs that ship to canada its easy, i just say has to pass CSA and PHSR, here is the cost. Done.
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Old February 18th, 2020, 05:36 AM   #27
mad4x4
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Why?


4 Estop buttons... THis could lead to its own problem of which one to push in an emergency
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Old February 18th, 2020, 07:32 AM   #28
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4 Estop buttons... THis could lead to its own problem of which one to push in an emergency
No. It is simple, an E-stop shall stop all dangerous movements in its vicinity.
It is perfectly OK to have several E-stops stopping the same movements, if you can access the movements from different sides, and you need to cover both sides and it is not possible with 1 E-stop, then simply place 2 E-stops.
Conversely, it is most definitely not OK to have several E-stops next to each other stopping different movements for exactly the reason that you shall not be put under the pressure of deciding which E-stop to press in an emergency.
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Old February 18th, 2020, 07:41 AM   #29
LadderLogic
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When we do jobs that ship to canada its easy, i just say has to pass CSA and PHSR, here is the cost. Done.
It might even be easier in the US: just give them an estimate of how much would it cost them if someone does get hurt. Everyone loves money after all.

And if you add possible prison term for criminal negligence if something goes really wrong, that may impress them even more.
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Old February 18th, 2020, 11:00 PM   #30
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It might even be easier in the US: just give them an estimate of how much would it cost them if someone does get hurt. Everyone loves money after all.

And if you add possible prison term for criminal negligence if something goes really wrong, that may impress them even more.
I 100% agree with you.

Just hard when after 20 years of them doing the same thing, trying to get my case across, just falls on def ears 80 percent of the time unless customer requires it.
Not knowing if an outcome could come on me personally, i do it to the best of my ability to cover myself. Which is just a shame, and frankly gets old fast, the fact that its a constant battle.
So yes a standard would be easier for my situation.
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