Unloading valve for hopper car

In a hopper for containing a dry fluent material, an unloading valve comprising:

• a pipe having a bore for communicating with the hopper and having a first end extending outside the hopper and a second end communicating with the hopper;
• a closure removably attached to the pipe at the bore defining a closed position that blocks the flow of material through the pipe bore from the hopper;
• and
• the closure having an inclined surface which extends within the pipe bore when the closure is attached to the pipe at the bore and confronts the fluent material within the pipe bore at an angle operative to cause the fluent material to become packed within the pipe bore when confronting the angled surface, the closure being oriented in the closed position so that an upper portion of the inclined surface is closer than a lower portion of the inclined surface to the central portion of the hopper;
• so that the packed fluent material within the pipe bore inhibits the material from leaking out the pipe when the closure is removed in preparation for coupling a material withdrawal conduit to the pipe.