Abderrahmane:
It is very difficult to understand acronyms when they are not defined in the same document or writing. This is especially difficult to understand when the document is transmitted between different countries – even when the countries speak the same root language. Since you are in Canada, I presume the following English terms:
ESD = Emergency Shutdown;
EDP = Emergency Depressurization;
IPF = Instrumentation Process Function (Valves?)
SRS = Supplemental Restraint System (a car's Airbag System)
I also presume Canada has governmental control and regulations regarding industrial safety – such as ASME (American Society of Mechanical Engineers), CFR (Code of Federal Regulations), as well as other local or district laws and regulations involving human, environmental, etc., safety. If so, does your organization (or industrial plant) have a department/individual who is in charge of meeting all necessary safety issues?
There is no international, United Nations, global, etc. agency or legal agency charged with establishing the same safety standards, requirements, or laws for everyone on earth. Therefore, I recommend you resort to your local, state, or federal government regulations regarding a plant process emergency shutdown and any requirements on how fast a shutdown valve has to operate. Even a written recommendation would suffice if there are no local standards or laws. Safety is a very serious issue and someone has to address it. I agree that a valve's closing time could be very important.
I don’t believe our Forum members can venture to consider or much less recommend what is the proper, legal, or “correct” closing time for a shutdown valve – unless they are experienced in Canadian safety regulations and requirements (assuming Canada is your location). We don’t even know the fluids, pressure, toxicity, etc of the application.