Abstract: The butterfly valve includes a pair of tailpieces which are threaded onto the outer ends of axially spaced pipe sections of a piping system and have a radially extending flange, a valve unit having a wafer-like body which fits between the tailpieces, and a pair of clamping members, each encircling one of the tailpiece flanges. All of these components preferably are fabricated by a powder-metallurgy process.The valve unit is supported between the tailpieces by a plurality of bolts which extend through axially alignable, circumferentially spaced apertures in the clamping members and the outer periphery of the valve body. After the butterfly valve has been installed, the valve unit can be removed without disturbing the piping system by removing the bolts or rotated 360.degree. without disturbing the piping by loosening the bolts so that the valve unit and clamping members can be rotated relative to the tailpieces.

Abstract: The valve includes an upper or inner portion housing, a first spring which acts on the top of a valve member and normally urges it into sealing engagement with a seat, and a lower or outlet portion carrying an actuator pin having an inner end which disengageably abuts the underside of the valve member and is actuated to lift the valve member against the biasing force of the first spring. The valve actuator pin has a vent passage extending from its inner end to atmosphere. When the actuator pin is actuated to open the valve, the valve member covers the inlet of the vent passage. When the valve is closed, a smaller second spring, carried on the inner end portion of the valve actuator pin, urges the inner end of the actuator pin away from the valve member, thereby opening the vent passage inlet so that the portion of the valve body below the valve member is vented to atmosphere. This permits the discharge conduit connected to the valve to be gravity drained after the valve is closed.

Abstract: A vent system includes a spring-loaded closed vent valve mounted in the upper portion of the truck tank and a spring-loaded closed safety valve mounted in the bottom of the tank. The safety valve has a discharge portion carrying an actuator pin which disengagably abuts the underside of the safety valve member and is actuated to lift the valve member to permit flow of gasoline from or into the tank. The vent valve member is operatively connected to the safety valve member by an actuating rod so that the vent valve is opened or closed when the safety valve is opened or closed. The safety valve, actuating rod and vent valve are provided with an overboard vent passage which extends from an inlet in the safety valve member to an outlet in the vent valve member. When the actuator pin is actuated to open the safety valve, the inner end of the pin covers the vent passage inlet and vapors are vented from the tank through the vent valve in a normal manner.