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Finding the Best Bulk Bag Unloader for Your Application

Finding the best type of bulk bag unloader for your application isn’t difficult, at least it doesn’t have to be. The most important part about the bulk bag unloader (bulk bag discharger) selection process is understanding what you need out of the machine.

Here at Spiroflow, we assist with bulk bag unloader projects all over the world. The conversations between our engineers and our customers revolve around understanding your application. We can recommend the best type of unloader for you once we know your specific needs.

This article is for anyone that’s not ready to have a conversation with a sales rep or engineer. I wrote this to help your research process. I hope this gives you an idea of what to expect when you’re ready to discuss bulk bag unloaders with a supplier.

Determining Your Requirements

Understanding your application is the starting point for any piece of custom-designed equipment. A supplier is going to ask about your goals, product, layout, measuring techniques, rate, and more. They want to get an idea of how to make the installation a success.

  • Will you be discharging by volume or by weight?
  • Are your bulk bags used for single trips?
  • Do you have height restrictions?
  • Forklift or hoist loaded?
  • Are you emptying more than just bulk bags?
  • Do you need total containment?

Bulk Bag Unloader Types

Now that you have an idea of what a supplier will ask from you, here’s what they could come back with. These examples are based on the models we offer at Spiroflow.

Bulk Bag Unloaders by Volume

This piece of equipment unloads bulk bags by volume into an integral conveyor process.

Loss-in-weight Bulk Bag Unloaders

Loss-in-weight bulk bag unloaders, sometimes called super sack unloaders, offer total control over the amount of product you wish to empty from your bulk bag. The transfer of material with this unloader is measured by weight. Load cells, mounted on the bag support dish, measure the changing weight of material as it is discharged from the bag.

Single Trip Bulk Bag Unloaders

This type of bulk bag unloader is ideal for applications with low value or hazardous material. This unloader uses a static or pneumatic knife to pierce disposable bulk bags with no bottom spout.

Low Headroom Bulk Bag Unloaders

These unloaders offer emptying solutions for plants with low headroom. They feature a removable top frame that can be set in place by a low lift fork

Integral Hoist Bulk Bag Unloaders

Operators without access to a forklift need one of these. This type of unloader is a fully self-contained unit. This functions with an integral “I” beam and a hoist for loading bags onto the unloader.

Multi-container Unloaders

You’ll need a controllable unloader and a subframe if you’re emptying more than just bulk bags. The unloader has an interlocked access door where the operator can untie the bag’s spout. The unit works well when batching operations require ingredients from different sources.

Total Containment Bulk Bag Unloaders

Applications with fine or potentially hazardous material need an unloading method that offers total containment. This type of unloader prevents contamination of the local atmosphere. It features a sealing device that inflates inside the bottom spout of the bulk bag. That device seals during the emptying process to keep dust from spilling and spreading.

Pharmaceutical Bulk Bag Unloaders

These unloaders are designed specifically with the pharmaceutical industry in mind. This is a high containment unloading system. From start to finish, the emptying process is totally contained. Spiroflow’s model comes complete with a liner spout clamping system. Spout closure bars, HEPA filtration system, and a sealed glove box add to the hygienic nature of this design.

Bulk Bag Unloader Options

Once your type of bulk bag unloader is selected, you may elect for some additional equipment. Here are some items to keep in mind or to ask your supplier about.

  • Spout closure bars
  • Hygienic bag spout clamp
  • Glove box
  • Liner remover and tensioner
  • Bag massagers
  • Metering feeders
  • Lifting frame liner clamp
  • Bag folding table
  • Static protection
  • Bag/sack dump door

Running a Material Test

When you think you know which unloader is best for your process, you should run a material test. It’s the best way to find out if the design works with your application and with your material.

Do you want more information?

Is there anything I didn’t cover? Feel free to ask us any questions you have about bulk bag unloaders. If you’re interested in bulk bag fillers or mechanical conveyors, let us know, we manufacturer those too. We also perform control systems integration if you’re seeking automation solutions.