| 摘要 |
<p>A CONTROL VALVE HAVING TWO INDEPENDENTLY DRIVEN VALVES The control valve has a quick-acting main valve and a safety valve which are independently operated either by the working medium which is being controlled or by an auxiliary pressure medium. The safety valve includes a rod which is secured to the piston of the safety valve drive and which extends through the piston of the servo-motor drive of the main valve. This rod has a longitudinal passage which communicates the upper chamber of the servo-motor for the safety valve with a discharge line for venting purposes or with the pressure medium in the upper chamber of the servomotor of the main valve for closing purposes.</p> |
