US Patent 7556238 Emergency shutdown system

An emergency shutdown system includes an emergency shutdown valve, a control line to carry a signal determinative of positioning of the emergency shutdown valve, a solenoid assembly coupled to the control line to effectuate the positioning of the emergency shutdown valve, and a junction device coupled to the control line and the solenoid assembly. In some embodiments, the junction device includes a switch, such as a relay, responsive to the signal to control whether the solenoid assembly is coupled to the control line and, therefore, energized.