Sch 1B para 5
In this Schedule “safety accessories” are defined as follows— (a) devices designed to protect pressure equipment against the allowable limits being exceeded, including devices for direct pressure limitation, such as safety valves, bursting disc safety devices, buckling rods, controlled safety pressure relief systems (CSPRS), and limiting devices, which either activate the means for correction or provide for shutdown or a shutdown and lockout, such as pressure switched or temperature switches or fluid level switches and safety related measurement control and regulation (SRMCR) devices; and (b) devices intended for equipment covered in the tables in paragraph 6 including where such equipment is incorporated into an assembly.