How A Bulk Bag Unloader Works

How Does A Bulk Bag Unloader Work?

So you may or may not know that a bulk bag unloader or what is also known as a bulk bag discharger is, it's a sealing device that inflates inside the bottom spout of the bulk bag and seals it during the emptying process to eliminate the risk of dust emissions. It also operates in conjunction with an automatic spout stretching device to promote a smooth and cylindrical path for material flow directly into a process vessel or integral conveyor. This patented feature is particularly valuable when products with poor flow characteristics are being handled.

It is important to ensure total discharge of product from the bulk bag when invasive powder is being unloaded to prevent the escape of material when the emptied bag is removed. For this reason, the Model T9 has bag massagers at the corners of the bag as well as the base. A patented pneumatic bag tensioner and an inner liner clamp prevent creases from forming during unloading which can trap residual material.


Height adjustment for bags of different sizes is provided as well as a lifting frame locator for correct alignment of the discharger with a process vessel or other equipment where the material is being unloaded. This feature enhances product containment.

Bag is placed on unloader by hoist or forklift.

Spout is pulled through the discharge dish with spout closure bars open.

With spout closure bars closed, bag is untied without release of contents. Bag spout located over inflation & tensioning device.

Spout closure bars are opened to release product.

Pneumatic stretching device is actuated to provide a smooth path for product through spout.

Bag massagers at each corner assist material flow & ensure total emptying.

Pneumatic bag tensioner retains bag shape.

The worldwide acceptance of bulk bags has brought about important changes in bulk materials handling practices to the point where even the pharmaceutical industry are using them to replace rigid IBC's. This is because bulk bags and their associated filling and discharge systems offer proven advances in hygiene and high containment operation.

bulk bag unloader image source: www.spiroflowsystems.com

The Cost Effective & Time Saving Bulk Bag Unloader

Bulk Bag Unloader

When it comes to safety, cost effectiveness & time, a bulk bag unloader is the most efficient alternative for containment & distribution of a variety of products.

T3 Loss-in-weight Discharger

Discharging By Weight

One of the global leaders in material handling is Spiroflow. Over the past 40 years, Spiroflow has worked closely with both small and large volume users - resulting in the development of a comprehensive and expanding range of bulk bag unloaders and transfer equipment. There are nine different models of bulk bag unloaders available to provide discharge by volume or by weight. A wide range of modular emptiers is also available, providing the complete solution to bag emptying and materials conveying.

Watch an animated version of the bulk bag handling process to see how the process works!

What Is A Bulk Bag Unloader?

A bulk bag unloader is also referred to as a bulk bag discharger, bulk bag emptiers & unloaders. Many different companies rely on bulk bag unloaders to handle all types of materials due to their speed, safety & cost effectiveness. Where small 50 pound bags were used almost exclusively, bulk bags (also called big bags) are a viable and effective alternative for containment and distribution.

Bulk Bag Unloader (Bulk Bag Discharger)

The worldwide acceptance of bulk bags has brought big changes to bulk material handling - not least in the pharmaceutical industry where they are replacing the use of rigid IBC's. Manufacturers of bulk bags, and associated filling and unloading systems have made strident advances in hygiene and containment – now offering containment levels as good as 25µg/m3. Lined bulk bags avoid cross contamination between batches and eliminate the need for and cost of cleaning/re-validation associated with traditional rigid bins.

Interested in learning more about the process? 

Watch the step by step bulk bag discharging process.