Safety

[Johnny Rotten]

Happy Friday. Currently working on a Siemens Safety PLC project. Slowly absorbing Siemens concepts. This is my issue which is a bit off topic of the PLC. The area(s) to be protected by guarding and etc are Category 3. We have determined that light curtains will not stop the equipment fast enough to meet Cat 3. So we are going with mechanical guards and non-contact safety switches and etc. It has been suggested that in addition to this we could add light curtains as a 'deterrent' and an 'added level of safety'. I disagree with this because once the light curtains are installed in the Cat 3 area they will be depended upon by the operators as a safety device and not meeting the criteria of Cat 3, they should not be installed at all.

Thoughts?

John

 

[danatomega]

If they don't meet your required category 3 then I should think they will not provide an 'added level of safety' and should not be used at all.

 

[adisharr]

I agree, I would stay away from installing anything that would provide a false sense of security. You may also want to consider requiring dual reset if operators can enter the guarded area and close the door (one reset inside, close door, one outside).

 

[TurpoUrpo]

Im just wondering what on earth are u building that can have mechanical guards instead of ligth curtains.

i might be biased, but i have ever seen light curtains used in places that need to have product moving through it, not people. I know in some applications ligth curtains could be used when part to be inserted -> part needs to move with hands. but still.

 

[adisharr]

Im just wondering what on earth are u building that can have mechanical guards instead of ligth curtains.

i might be biased, but i have ever seen light curtains used in places that need to have product moving through it, not people. I know in some applications ligth curtains could be used when part to be inserted -> part needs to move with hands. but still.

Of course it's application dependent but it's done all the time. We do a lot of hard guarding combinations with light curtains and safety laser scanners. Some areas we use muting light curtains for one or two way product travel through the curtains.

If the machine needs to be easily accessible and we can stop it fast enough then we'll use light curtains. The trick is to now allow the machine to start with an operator in the protected envelope. For that we'll use floor mats or a floor mounted scanner.