Emergency isolation valves are distinguished from control valves by function and by performance requirements. Emergency isolation valves are designed to provide tight shutoff when closed, full pipeline capacity when open, and the ability to open or close quickly. Emergency isolation valves are actuated by Emergency Shutdown System commands, which, in the event of fire, vessel rupture, pipe rupture, or other loss of containment, function to isolate process equipment and to stop the release of hydrocarbons or potentially toxic materials. Emergency isolation valves are typically operated by actuators. As with other block valves, there is typically no requirement for throttling, and they are operated only occasionally. Section 4 of SAES-J-700 disallows the use of control valves as emergency isolation valves.