Dual independent input hydraulic shutoff

Claim 1

A flow line shutoff for a hydraulic management system having two independent shutoff command input sources, comprising: a shutoff valve means disposed in said flow line a sequencing valve means, having a shutdown port, for controlling flow through said shutoff valve means line, said sequencing valve means operable between a first, open flow state and a second closed flow state in response to a selected pressure signal delivered to said shutdown port; pressure selector means for selecting the control pressure signal by establishing exclusive fluid communication between the shutdown port and one of two input pressure signals, the selected input pressure signal having a fluid pressure greater than the deselected input pressure signal; a first shutdown valve, actuatable between a first position and a second position, wherein said first position establishes exclusive fluid communication between a high pressure input signal and the pressure selector, and wherein said second position establishes fluid communication between a low pressure drain line and the pressure selector; and a second shutdown valve, actuatable between a first position and second position wherein said first position establishes communication between a high pressure input signal and the pressure selector means, and wherein said second position establishes fluid communication between a low pressure drain line and the pressure selector means.