Abstract: A self contained hydraulic valve system, for controlling the flow of a normally gaseous fluid such as, for example, anhydrous ammonia, includes a hydraulic valve connected to a pressurized vessel holding said normally gaseous fluid, a master cylinder hydraulically connected to said valve and controlling the operation thereof, and a hydraulic connection between the hydraulic valve and master cylinder. In operation, when the manual lever of the master cylinder is depressed, the hydraulic fluid within the self-contained system is pressurized thereby forcing the hydraulic valve open.