FIBC Bulk Bag 101: Types of Bag Bottom Closures Explained

FIBC Bulk Bag 101: Types of Bag Bottom Closures Explained

Updated: 3-22-2022

FIBC Bulk bags come in many sizes, shapes, and materials. There are a wide range of customizations to consider when choosing the right bulk bag. The type of closure used to seal the bag is an important features because it can affect the integrity of the bag. There are many different types of bottom closures that can be customized to fit your application. 

In this blog we will go through some of the most common types of bulk bag bottoms to help you identify which type is the best for you. For regular updates, subscribe to our blog by filling out the “Subscribe to our blog updates” form to the right.



Spout Bottom

A bulk bag with a spout bottom is a bag that has a funnel-like opening at the bottom, which allows the bag to be easily emptied. These spouts are tucked into the bottom of the bag and remains closed until you are ready to release the product. Bulk bags with spout bottoms are often used for storing and dispensing powders and other granular bulk material.

The discharge spouts are the most commonly used of all the bulk bag bottom closures and can be customized to the right size for your application.



Spout Bottom with Safety Valve (aka Iris Closure)

A spout bottom with a safety valve is a device that is used to control the discharge of the material from a bulk bag. It is used to control the flow of bulk material released from the bag. The safety valve also allows the bulk bag to be emptied without the release of dust and particles. This can be very important when working with hazardous materials. 




Spout Bottom with Cover (aka Star Closure & Petal Cover)

This type of closure uses a piece of fabric that's sewn between the spout and the petal closure which is used to hold in the spout. Then a square piece of fabric is sewn over the spout bottom to secure the spout bottom. The spout bottom with covers are designed to keep the contents inside the bag contained, minimizes contamination risks, and prevents leakage. 



Skirt-with-Flap-FIBC-Bulk-Bag-National-Bulk-Bag.jpgDischarge Spout with Flap

The discharge spout with flap, also known as a sanitary flap,is a flap that protects the entire bottom of the bulk bag. These are often times used for ease of discharge, create less wear on the bottom of the bulk bag, and keep the discharge area clean.




skirt-with-flap-copy-1.jpgB-Lock Closure

A B-lock closure, otherwise known as a cord lock, is a type of bottom closure that uses a cord to secure the spout on the bottom of the bag. Cord locks are useful for preventing any loss of contents due to accidental opening of the bag. They are available in a variety of lengths and sizes and can be used to replace hand tied knots. B-Lock closures can also be used on the spout top of the bag. 



Conical Bottom

Bulk bags that require a conical spout bottom are often times used for materials that do not flow as freely as dry powders or grains. The bottom of these bulk bags are cone shaped which allows dense/sticky materials like clay, slurries, etc.. to "flow" out of the bag. 



Full Open Discharge

Full open discharge is a type of discharge that opens up the bottom of the bag in its entirety. These types of bottoms are used for non flowable product or products that clump over time. When the bottom is opened, the product  is released all at once. Be sure to take note that if accuracy is important, this type of bulk bag bottom is not recommended. 


Thanks for Reading!

product weight + calc.pngThanks for reading about the advantages and disadvantages of each bag bottom closure.

Safety and reliability are our top priorities. Each bag that we sell has a safe working load (SWL). To make sure the product you’re packing will not exceed the SWL of the bag you’re interested in, you’ll need to know the bulk density of the product you’re packing as well as the cubic foot capacity of the bag.

Click the button below to download our Product Weight Guide and FIBC Volume Calculator to help you determine how much weight a specific bag will hold.


March 22, 2022

Categories: Bulk Bag Construction

About the Author: Janette Lais

Janette is the Director of sourcing for National Bulk bag. Janette is also a graduate of the University of Minnesota in Minneapolis. Janette has been in the packaging industry since 2004 and has held many roles such as Operations and purchasing manager, Purchasing management project manager. Before entering the packaging industry, Janette spends 19 years at a manufacturing facility where she held production scheduling, product manager, and purchasing manager position. Janette is an outdoor enthusiast and enjoys hiking and fishing in her free time. She also enjoys spending time with family and friends and her three dogs.

Browse our 50+ in-stock bulk bags

FIBC Bulk Bags, In Stock FIBC list, National Bulk Bag

We stock one of the largest FIBC Bulk Bag inventories in the United States. Whether you are packing chemicals, food, minerals, resin, sand, soil or any dry flow-able product, we stock or can manufacture a bag to meet your requirements.

Subscribe to our blog updates