Why use a bulk bag with a liner?
Using a plastic poly liner inside the bag has two advantages. First the dust cannot get through the woven bag itself. Fine powders can be pushed through the openings in the woven material of the bulk bag. The second is that the liner can be made with a neck that can be used to achieve a dust tight seal with a properly designed bulk bag fill head.
What is a bulk bag fill head? – The simple approach…
Bulk bag fill head designs vary but the goal is the same – to allow for bulk materials to be quickly filled into a bulk bag without losing any of the material and reducing the dust produced. Bulk bags with liners generally narrow to about a 14" diameter at the bag neck. The simplest bulk bag fill head approach is to attach the bag neck to a piece of pipe that is slightly smaller in diameter. The liner is attached using a strap or cord. This design is simple and inexpensive but does not address a critical issue with respect to dusting. As the material enters the bag, there is nowhere for the displaced air to go. The air must escape either through the fill head or it is forced out between the bag neck and the fill head creating a dust cloud.
Properly designed bulk bag fill head features
The critical points to address in designing a bulk bag fill head are to provide a dust tight seal on the bag neck and to provide a path for displaced air to escape. The way to deal with this is to manufacture the fill head as a tube within a tube. The bag spout can attach to the outer tube and the product can flow into the bag through the inner tube. This double tube approach leaves an open space between the tubes for the displaced air to escape. A large exit port that can be directed to a dust collection system is attached above the bag neck. The seal on the bag neck can be made with an inflatable bladder that pushes out and captures the bag neck. For oversized back necks or duffel top bags, a special pinch ring or split ring can be used with the inflatable bladder.
By solving these critical issues, bulk bags can be filled rapidly with a minimum release of dust creating a safer, cleaner working environment.
Tim Porco – Erie Technical Systems Inc. – timp@erietechnicalsystems.com
