US Patent 7209806 Self-contained electronic pressure monitoring and shutdown device

The invention is a self-contained process shutdown device that detects abnormal pressures and initiates shutdown by removing the pneumatic or hydraulic pressure needed for a given process or flow to continue. The process' pressure is detected by means of a switch-gauge (a pressure gauge with high and low alarm electrical contacts) which has a pressure sensing port connected to the monitored pressure. The contacts from the switch-gauge are connected to an electronic logic circuit that sends one or more shutdown pulses to trip a pulse driven solenoid and initiate the shutdown. This device provides indicator lamps to show statuses and alarms as well as switch or pushbuttons to activate the “Reset” and “Test” functions.