| 摘要 |
<p>A control system for shutting down a fluid system when its pressure falls outside of preselected high and/or low pressure limits which control system includes a pressure responsive shut-down valve connected to shut down said fluid system, a control valve controlling the actuating fluid to said shut down valve, an activator connected to actuate said control valve and at least one pilot connected to sense the pressure of the fluid system and to provide response to the fluid system pressure falling outside its preselected limits to the activator whereby said activator moves the control valve to shut-down position, a manual override having a locking piston externally actuated to lock the piston of said activator in normal position for start-up, said locking piston being disengaged responsive to pressure differentials thereacross when pressure in the fluid system exceeds the preselected low pressure limit.</p> |
