A safety device or system is the final element to protect pressure equipment from exceeding its allowable limits.
It is important to consider not only the pressure-relieving device but also the whole of the equipment protected, in order to ensure that the relieving pressure is not exceeded.
BS ISO 4126-9:2008 covers the application and installations of safety devices for the protection of pressure equipment. This includes elements such as safety valves, safetyvalves and bursting disc safety devices in combination, pilot-operated safety valves and controlled safety pressure-relief systems.
BS ISO 4126-9 gives normative references and terms and definitions. It also specifies requirements for:
Equipment connected together in a system by piping of adequate capacity, which is free from potential blockages and does not contain any valve that can isolate any part, can be considered to be a safety system for the application of pressure relief.
ISO 4126-9:2008