Bulk bag unloaders come in three primary frame configurations – Fork Loaded, Hoist & Trolley, and Half Frame – and deciding which type best fits your application can be tricky. You must take cost, configuration, and application influences into account, as well as ergonomic features and flexibility options. So if you’re struggling to select the best frame type for your needs, we can provide some of those answers. We have included brief descriptions of each type of bulk bag unloader and summarized its advantages and applications. We’ve also included some alternative design options for those with more unique, individualized needs.
Half Frame bulk bag unloaders are primarily used in locations where an existing I-beam and hoist are present. However, they can also be used in tandem with a forklift to create a simple, inexpensive discharging system.
If you’re looking at Half Frame unloaders, consider your location carefully (the unit must be centered under the beam/hoist. Also, make sure to review the down-stream process. When using a forklift to support the bag, the key is to ensure that operators are not in jeopardy of being pinned between the frame and lift or run over in the process of untying the bag.
Half Frame units are commonly used for high-speed discharging systems via bag piercing systems. These systems cut the bag as it is lowered onto the bag support and then quickly discharge it so the next bag can be loaded and discharged. Often the bag piercing system will also use a quick-release bag support frame for the forklift.
Fork Loaded Super Sack® frames offer full bag support from the top and bottom. They use a lifting frame (spreader bar, bag lift adapter, etc.) to attach the lift loops of the bags, and then they lift and nest the bag/adapter on support bars, which can be adjusted within a structural frame.
Why should you consider a Fork Loaded frame? The primary advantages of this unit are that the bag is completely supported and the system costs less than a Hoist & Trolley frame.
Fork Loaded frames are most appropriate in applications in which bag sizes changes are rarely (if ever) required. Why? While it is easy to make a change for a new bag size, due to the location (a high position on the unloader frame), the switch typically requires a man-lift or rolling staircase to accomplish.
Hoist & Trolley
Hoist & Trolley units offer all of the support features of a Fork Loaded frame, but they also include a traversing, lifting hoist to insert the big bag into the frame. To use the system, the operator extends and lowers the bag adapter (spreader bar) just above the bag, attaches the loops, and lifts the bag up and into the frame. Then, they lower the bag into the receiver pan for untying and dispensing.
There are only two downsides of Hoist & Trolley units. First, they can be costly (hoist and beam are expensive to integrate). Second, some plants’ health and safety programs require guarding or lock-out of the lifting area below the bag. While this can easily be added to the system, it is an additional application consideration.
When handling multi-sized flexible intermediate bulk containers (FIBCs), or if a forklift isn’t available in the area, a Hoist & Trolley system can be extremely advantageous.