Quick Question

[~K-Pow~]

Hey i know this has nothing to do with computers but there are alot of smart people in this forum so maybe somebody can help me.

I was wondering if there is a site where i can get information on Safety Catagories??? I'm installing some light curtain's for a company and they want to know what is the difference bewteen Catagory 3 and Catagory 4, i've googled it but come up with the same information everytime.

Any help at all would be appriciated.

 

[lhuser]

I think Category 4 is a lower saftey than Category 3. The third will give you more lighting in the room I guess.

 

[~K-Pow~]

Sorry lhuser i probably should of explained this better.

http://www.ab.com/safety/prod_direc...ns/guardshield_safe_light_curtains/type2.html

Here is what a light curtain is. It's a safety device used to stop a machine when a hand or finger breaks the plane of the beams.

 

[lhuser]

Ah, now I get it.

I think, then, Category 4 is a lower safety, but it wil still stop it. The only difference is that it might be a little slower to stop or it might be a little more cheaper than category 3. Although, if it is not that, it could just be the size or fabric of it. The sensor plays in there too.

 

[~K-Pow~]

Yeah i know what your saying lhuser. Catagory 4 is the top catagory in this case i was just looking for descriptions of the catagories, i've googled it and stuff but was wondering if you guys may of had any luck. I believe the standard is EN-941

 

[root]

How They Work Safety light curtains are easy to understand. A photoelectric transmitter projects an array of synchronized, parallel infrared light beams to a eRceiver unit. When an opaque object interrupts one or more beams the control logic of the light curtain sends a stop signal to the guarded machine.

Light curtain applications are often categorized by the type of guarding required. Protecting an operator from the hazards associated with material positioning or where a process is performed is called point of operation guarding. The point of operation is often called the zone of hazardous operation, or the pinch point. This type of guarding is associated with mechanical and hydraulic power presses, molding presses, stamping, forming, riveting, eyelet and automated assembly machinery. Light curtains used in these applications are typically selected for finger and hand rotection.
Perimeter guards protect the perimeter or boundary defined by a machine, robot or other equipment. In these applications, the light curtains are generally selected to detect the presence of personnel and signal the machine controller to prevent hazardous conditions while personnel are present within the protected area. Also, the light curtain reset switch must be located outside and within view of the protected area to prevent inadvertent resumption of machine motion. Light curtains for perimeter guarding applications are generally selected for torso detection.

regardless of the category, each will conform to H&S regulations as set out by the IEE, this is a specific regulation and here is the documentation about that.
http://www.iee.org/oncomms/pn/functionalsafety/HLD.pdf
all light curtains will also conform to standard in the spec IEC61496 (but I couldn't find a link for that)

(two more quotes)

lightcurtains are suitable for safeguarding high risk (category 4) applications such as presses, press brakes, robots and other potentially dangerous machinery.

and...

lightcurtains are suitable for safeguarding medium risk (category 3) applications such as palletisers, stretch wrappers, automated warehouses and other automated applications.

So there you have it, Light curtains come in many different size and shapes, but a brief outline it that

category 4 is to be used for safeguarding dangerous/high risk machinery
whilst category 3 is to be used for safeguarding mediumrisk machinery.

Type 4 is small object detection, (such as fingers or hand).
whilst type 2 is large object detection such as body

so if you wanted to guard a hydraulic press, that was pressing bottle caps, (which a person loaded manually), you'd want category 4, type four.

but if you have an automated production line wrapping pallets, you'd want a category 3 type 2, cause you only need to stop if some idiot is walking on the production line.

 

[~K-Pow~]

Thanks root. This information will be quite helpful to me. The machine is a press, so i need catagory 4.

Thanks again

 

[lhuser]

Ah, so Categories varies depending on the machinery you use.

 

[~K-Pow~]

Categories vary depending on the amount of protection you require. There's a graph if i can find it i'll put a link to it so you will have a clearer picture of what i'm saying.

 

[root]

Ah, so Categories varies depending on the machinery you use.

Pretty much, the more dangerous the machine the higher category of safety protection needed.