A safety relief valve structure for a railway car having an enclosed shell which is adapted to be placed under an internal fluid pressure, especially for unloading particulate lading. A pilot-operated safety valve on the car has a main valve inlet communicating directly with the interior of the car, and a separate pilot line provides fluid communication between the interior of the car and the safety relief valve for controlling the operation of the valve. A filter is positioned in the separate pilot line and minimizes any passage of air entrained lading to the safety valve through the pilot line. The filter comprises a housing and a filter element within the housing through which the air and any entrained lading particles pass. The filter element has a micron rating between around five and 25 to entrap lading particles of a micron size greater than the micron rating of the filter element.
A three-way valve is provided in a conduit (s) running from a pressure chamber in a railroad car allowing in one position the pressure in the pressure chamber to be transmitted through the conduit, and in another position high pressure gas may be applied through the conduit to remove contaminants and moisture therefrom and force the same back into the pressure chamber.
An elongated hollow tube extending between the forward and after ends of a hopper trailer serves as a ridge pole for a protective tarpaulin covering a commodity, such as rice or wheat, forming the trailer's cargo. Conduits connected to the ends of the tube extend downwardly below the margin of the tarpaulin so as to conduct atmospheric air into the tube. From the tube the air discharges downwardly through an opening in the tube vertically above the hopper door and thereby equalizes the air pressures on both sides of the tarpaulin as the commodity is withdrawn from the hopper and tends to form a "vacuum" beneath the tarpaulin.
A cleaning system for sleeve-type air filters featuring top removal of sleeves of the filtering media and increased filtering capacity, using sharply pulsed backflushing air of short duration from a single source for cleaning the sleeves which requires substantially less power and simpler mechanical structure than conventional filters of similar capacity. Filter sleeves depend from clean air outlet ports which are arrayed in concentric rings in a porting plate in closely-spaced relation one from the next at uniform circular and radial pitches allowing more sleeves to be packed in the porting plate which separates the clean air section from the dusty air section of said filter and more capacity from the same size filter than was heretofore possible. A tank is repetitively charged with air to a set pressure by a pump and the pressurized air is released by a pulse generating valve for distribution of the air to said sleeves for backflushing at essentially random frequency. Each sleeve in the filter receives, on the average, one pulse of cleaning air every 2 to 5 minutes.
