Abstract: A valve including a primary tube, a secondary tube, a piston-like element, a pin, and a rotatable control ferrule. Two reduced diameter portions are formed on one end of the primary tube, in which the outer portion with a threaded outer surface has a smaller diameter, and the intermediate portion has a larger diameter. Two slots are formed on the opposite sides of the intermediate portion. The secondary tube has a threaded bore for making a threaded connection with the outer portion of the primary tube. The piston-like element is composed of a head and a rod with a transverse hole near its free end. The pin is slidably located in the hole of the rod. A control ferrule is rotatably disposed between the primary and the secondary tubes on the outer periphery surface. Two guide slots are formed in the annular inner surface of the control ferrule for receiving and guiding both ends of the pin in order to control the vertical movement of the piston-like element.