ESD/ESV valves are the final defence against process misreactions. These valves have a function which requires much more reliable performance than standard remotely operated on-off valves. Still today ESD valves are ranked often as ordinary shut-off valves in specifications. Valves as such may still remain the same but being a part of Safety Instrumented Function (SIF) the performance expectations are much higher. There must be a prove for a reliable long term performance. MTBF (Mean Time Between Failure) number needs to be given to Safety calculations (SIL).
NELES (2005) ESD Valve Selection Guide