Some Good safety valve designs and tips at the Emerson blog.
Is a follow on from this post on Partial Stroke testing as a supplement to standard full stroke testing.
It is a nice reminder for me that despite the fact that IP connected systems are increasing in frequency the simple designs are best especially when it comes to safety.
This brings me back to something I should have included in original Physical Security Layer and somewhat touched on in my Continuation of the Network Layer Security. It is essential that your safety systems cannot be adversely impacted by the operations or failures of any of your other systems. I mentioned in the Network layer post that they should be separate from the other networks but the real advice is that they should be as simple as possible, physically and logically isolated from all other systems (in terms of connectivity obviously placement is dependant on need and overall system design), and most importantly protected from failure modes that the other control systems might be subjected to.
This is a great blog.
Does anyone out there know if Invensys, Honeywell, Rockwell/ABB, or Siemens have a blog like this? I haven't been able to find one but if they do I would really like to add it to my RSS stack.