TOP OPERATED TANK CAR LADING VALVE ALSO OPERABLE FROM THE BOTTOM

摘要

In a top operated tank car valve, a mounting flange is welded to an opening in the bottom of the tank. A valve seat is located inboard of, and above the lower surface of, the mounting flange. A vertically extending cage is integrally attached to the mounting flange. A top operator extends to the top of the tank, and a stem is attached to the lower portion of the top operator. The stem extends into an opening in a valve closure plug. A non-round cavity is formed in the bottom of the stem. The closure plug includes a seat which engages the valve seat located within the mounting flange. The closure plug includes a circular guide ring which engages a portion of the vertically extending cage as the closure plug moves between open and closed positions. The closure plug includes a vertical, generally central opening which communicates with the circular head portion of the valve stem. A retainer, held in place with retainer fasteners extending from the bottom of the retainer into the closure plug, holds in place a seal located in a circumferential groove in the closure plug. The retainer includes an extension which extends through the vertical, generally central opening in the closure plug. The retainer fasteners can be removed from the bottom of the car, providing access to the non-round cavity in the valve stem. Thus, the closure plug may be opened from the bottom of the tank with a tool extending through the vertical center opening. Since the valve seat is located within the mounting flange which does not extend more than one(1) inch below the tank bottom, a tank car skid is not needed to comply with AAR regulations concerning projections from the bottom of railway tank cars.