SiePortal

The integrated platform for your product selection, buying and support workflow - bringing together Industry Mall and Online Support.

Products & Services
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
Support Support
{{(apiData.Support | filter:{'rank':1}:true)[0].title}} Support
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
MySiePortal MySiePortal
{{(apiData.MySiePortal | filter:{'rank':1}:true)[0].title}} MySiePortal
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
Cart ({{apiData.CartCount}})

Navigation

3RK3 Basic safety inputs

1/18/2010 3:11 PM	Rate (0)
FunStuff Posts: 103 Rating: (10)	I am working on bringing our plant to a safer state and will be implementing some stop circuits with a 3RK3 basic relay. My question is this: I have seen many examples posted of SIL 1,2,3,4.. systems that have very basic E-Stop circuits implemented and always those circuits are based on hand/gaurd or light curtain controls stopping motion. The plant I work in is very much different as we have very little danger from motion as most of our dangers are from chemical release and would not want the operator any where near the system to shut it down. How does one implement a properly rated safety shutdown of a situation that would result in a chemical release using a safety relay or plc. I have never seen or found a monitoring device that was safety rated such as a pressure switch, chemical detection sensor etc... Does the situation then become a calculation based on the odds of failure of the device to determine how many redundant monitoring devices are needed to feed the safety system? Any material on evaluating and designing safety stops for chemical systems would be appreciated.
FunStuff Posts: 103 Rating: (10)
Suggestion To thank Quote Answer

1/18/2010 4:13 PM	Rate (0)
Safety1 Posts: 73 Rating: (20)	Hello FunStuff, Generally speaking chemical applications are based on Process Safety standards such as IEC61511. They are normally Low Demand mode [PFD] applications and therefore are not calculated in the same way as High Demand mode applications [Machine Safety, PFHd]. The definition for Low Demand based on IEC62061"eg frequency of demands on a safety system is no greater than one per year and no greater than twice the proof-test frequency." The SET calculates SIL based on IEC62061 which is High Demand Mode of operation for machine applications. Please look at the following links they might help http://support.automation.siemens.com/WW/view/en/35444324 www.siemens.com/process-safety
Safety1 Posts: 73 Rating: (20)
Suggestion To thank Quote Answer

1/18/2010 5:48 PM	Rate (0)
FunStuff Posts: 103 Rating: (10)	I havethree excellentSiemens documents that I found and according to those it would seem that my systems need to be a PL C or SIL 1. This is very achieveable with a 3RK3 system but I need to perform the calculation on a pressure sensor using the factory data to see what subsystem SILCL is. One of the documents has many examples but I either missed or am failing to find the correct way to take a non-safety rated device (pressure switch) and perform an evaluation on it to determine the SILCL of the subsystem. Do you have any examples of this calculation for a non-safety rated device? I have attached one of the documents. Attachment Safety Design Siemens Example Doc.pdf (888 Downloads)
FunStuff Posts: 103 Rating: (10)
Suggestion To thank Quote Answer

Share this page:

Share this page on...