Pressure relief valve

Реферат: ABSTRACT OF THE DISCLOSURE Disclosed is a safety vent for a covered hopper car which has a hopper and a pneumatic discharge mechanism adapted to be connected to a fluid pressure system for material unloading. The vent includes a tubular member having a tubular wall, one portion of the wall being connected to and communicating with the interior of the hopper car and a second portion of the wall communicating with the atmosphere. A seating surface is on one of the portions and a valve member is solely seated upon the surface and is rupturable at a predetermined design pressure outside the car. The valve member is adapted to seat fluid tight against the surface solely by reduction of pressure in the car, and the valve member includes a stretchable diaphragm stretched transversely across the tubular wall in tensioned condition where, upon rupture of the same, the diaphragm is substantially destroyed to permit flow of fluid through the tubular member.