Emergency Shutdown System (ESD) Definition Based On API RP 14C

Hi,

I just want to share about my problem to define between Safety Instrumented System (SIS) and Emergency Shutdown System (ESD). Is there any deferences? I read ANSI/ISA 5.1 2009 to find right symbol for ESD but I got nothing, I also asked to my mentors but still didn't get enough information to know. And enlightenment came when I asked to Google and found forum with subject "ESD vs SIS". From what I know after read information from that forum "ESD is a manual input for SIS" and another informed we should read API RP 14C to know clearly about ESD. So I tried to find that standard and found it. So here is ESD definition I cited from that standard:

An Emergency Shutdown (ESD) system is a system of manual control stations strategically located on a platform that, when activated, will initiate shutdown of all wells and other process stations. This system may include a number of independent process shutdown systems that can also be actuated separately. Activation of the ESD system should result in the termination of all production activity on the platform, including the closing of all pipeline SDVs. The ESD system should be designed to permit continued operation of electric generating stations and fire fighting systems when needed in an emergency.

The ESD system provides a means for personnel to manually initiate platform shutdown when an abnormal condition is observed. Fusible elements of the fire loop may be integrated with the ESD control loop.

So now I know that ESD is part of SIS for safety purpose to protect either plant or people and ESD will active when there is someone activated (manually).

That's all.