System and filter for preventing contamination of particulate material in railroad car during transportation and unloading

A system for transporting and unloading a railroad hopper car loaded with particulate material while preventing contamination of the particulate material during the transportation and unloading, comprising the steps of:

• removing an originally installed metal cover from each originally provided opening in a hopper car to be used for unloading particulate material which has been loaded into the car prior to transportation;
• placing a bag filter on each opening from which a metal cover has been removed;
• replacing the originally installed metal cover on each opening;
• then transporting said car to its unloading destination with the bag filters and metal covers in place to prevent contamination of the particulate material from external sources during such transportation;
• thereafter removing the metal cover and bag filter from a first of said openings and attaching a vacuum hose thereto for unloading the particulate material;
• removing the originally installed metal cover from a second of said openings;
• leaving the bag filter on the second of said openings during the unloading of the material;
• and
• then unloading the particulate material from said car by applying a vacuum through said first opening and thereby drawing air in through said bag in said second opening.