Filters — the unseen heroes of pneumatic conveying
The unseen heroes of any pneumatic conveying system are the filters. A conveying system typically has several of them, but many of them go unnoticed and, hence, aren’t maintained, which can lead to serious conveying problems. This column discusses inlet and discharge filters for vacuum and pressure pneumatic conveying systems, with tips on where to locate the filters, how to choose them, and how to maintain them.
The inlet air in vacuum and pressure pneumatic conveying systems is usually filtered. In a vacuum conveying system, which can be a railcar-unloading system or a conveying system with a feeder for introducing material into the line, the inlet filter prevents foreign material from entering the system and contaminating the conveyed material. Thus the filter is usually installed at the air inlet, before the material pickup point or feedpoint. In a pressure conveying system, the inlet air is almost always filtered to prevent contaminants from entering the system’s air mover (the fan, blower, or compressor), so the filter is installed prior to the air mover. The inlet filter is typically a single cartridge filter with pleated fabric media inside a cylindrical housing.