Type-D Bags

What does FIBC stand for?

Flexible Intermediate Bulk Container. You may also see them referred to as Bulk Bags, Big Bags, and Totes.

What are FIBCs made from?

100% virgin polypropylene

What sizes do FIBCs come in?

FIBCs come in many different sizes and styles but can be customized for your product.  Most bags come with a standard base dimension of 35″ x 35″ but once again all bags can be customized for your product.

How do you move a FIBC?

Bulk bags can be lifted one of the following examples:

10″ lift loops

stevedore strap

lifting sleeves

single point crane lift

The above are just a few options.  Lifting options can vary and can be custom made.

How do you empty a FIBC?

FIBCs can be emptied several different ways but the most common discharge is an outlet spout which is a spout that is attached to the bottom of the bag.  Sometimes the discharge spout is inside a closure on the bottom of the bag such as a petal closure, pajama closure or star / x-cut closure.  The closure is designed to protect the spout and to prevent the product from leaking / sifting out of the outlet before required.  Discharge spouts can vary and can be custom made.

We want to start using FIBCs.  How do we go about getting started?

You will need the following information:

Style of bag

Fabric weight

Type of top and bottom openings

Dimensions of the FIBC

Safety ratio desired

Weight you desire in the bag

How many times will the bulk bag be used

Any extra information that you feel is important

What is a Food Grade bag?

A food grade bag has been FDA approved for use in food packaging.  Special steps are taken during the manufacturing process to ensure its safety.

What is a U-Panel bag?

A U-Panel bag requires 2 seams along 2 opposite sides to create 2 panels and a “U” Panel shape

What is a Tubular bag?

Circular fabric with no side seams.  Capacity is up to 4000 lbs.  The tubular body design is ideal as a linerless option for fine and hygroscopic materials.  It is also an excellent alternative to the original four panel bag construction.

What is a 4-Panel bag?

A 4-Panel Bag is the original polypropylene design which has become the industry standard.  The versatile four panel construction is excellent for a variety of applications.  This four panel design requires seams along four separate pieces of fabric sewn to create a 4-Panel Bag.  Capacity is up to 4400 lbs.

What is Baffle?

Pieces of fabric or other material sewn across each corner of a tubular or four – panel bag to improve a bag’s squareness, appearance, improve the stability of the load and to more efficiently utilize storage or shipping space.

What is a Type “A” bag?

A type “A” bag is constructed from non-treated insulating fabric.  No requirements are specified for type “A” FIBC’s as they are not intended for use in potentially explosive atmospheres.  No static protection.

Used safely to transport non-flammable products

There are to be no flammable solvents or gases present around the bag

DO NOT USE to transport flammable products

What is a Type “B” bag?

A type “B” bag is constructed from insulating fabric but has a breakdown voltage less than 4KV.  This provision prevents the risk of energetic propagating brush discharges which can ignite dust-air mixture.  Type “B” bags may be used in the presence of the combustible dusts with MIE of greater than 3mj but in the absence of flammable vapors of gases.  Low breakdown voltage.

Used safely to transport dry, flammable powders

There are to be no flammable solvents or gases present around the bag

DO NOT USE to transport flammable products

What is a Type “C” bag?

A type “C” bag is constructed from fabrics having inter-connected conductive threads.  The bag must be electrically grounded during filling and emptying.

Used safely to transport flammable powders

Used safely when flammable solvents or gases are present around the bag

DO NOT USE when ground connection is not present or has become damaged

What is a Type “D” bag?

A type “D” bag is constructed from antistatic fabric that includes static dissipative and antistatic yellow threads.  This unique system is patented worldwide.  Does not require grounding.

Used safely to transport flammable powders

Used safely when flammable solvents or gases are present around the bag

DO NOT USE when the surface is contaminated or coated with conductive material such as water or grease

Can FIBCs be used more than once?

FIBC’s can be used more than once if you have a bag with a 6:1 SF.  Some users reuse a FIBC with a 5:1 SF but this is not recommended!  If you reuse a FIBC with a 5:1 SF you have to take into consideration that the fabric might be worn down or the loops could be breaking down, etc.  If you plan on using a bag more than once it is recommended that you custom order it with a 6:1 SF.

Flexible Intermediate Bulk Containers (FIBCs) are extensively used for packing, storing and transporting a variety of materials (chemicals, minerals, food products, agricultural products, fertilizers, plastics, cement, etc) in fine dust, powder, granular or flake form. The use of FIBCs in industrial applications is ever-growing as they are a cost-effective packaging and transportation means; however, there are associated electrostatic ignition hazards that one should be aware of when using FIBCs for packaging and transporting combustible/explosible materials and/or when flammable gases and vapor atmospheres are present in the solid media.

Electrostatic Discharges

Electrostatic charge generation normally occurs due to the process of contact and separation which takes place between individual powder particles and the conveying equipment upstream of the FIBC during filling and between the powder particles and the internal surfaces of the FIBC during emptying.

The types of discharges that may occur due to the buildup of electrostatic charge on the FIBC include:

> Brush Discharges from the surfaces of standard insulating FIBCs and liners. Brush discharges can ignite flammable atmospheres requiring a Minimum Ignition Energy (MIE) of up to approximately 4mJ.

> Propagating Brush Discharges from the surfaces of insulating FIBCs and liners, which have electrical breakdown voltage greater than 6,000 volts. Propagating brush discharges can ignite flammable vapor, gas and dust cloud atmospheres.

> Spark Discharges from conductive parts of groundable bags and conductive liners if left ungrounded.

There are currently four types of FIBCs; namely Type A, B, C and D.  Table below provides the features of the various FIBC types and the testing requirements for each FIBC.

Table 1

The use of liners in any type of FIBC can increase the risk of an electrostatically initiated flash fire or explosion.  There are three types of liners that are permitted to be used in a particular type of FIBC depending on the electrostatic properties of the liner material (see Table 2).  Depending on the liner type, the following electrostatic properties may need to be determined for liners:

> Surface Resistivity,

> Breakdown Voltage,

> Liner thickness,

> Resistance to Groundable Point

These tests results provide valuable information that will be utilized to determine the safe use of a particular type of liner with a specific type of FIBC.

Features of Various Types of Liners for use in FIBC 

Selection of a Particular FIBC and Liner Combination

It is very important and safety critical to ensure that:

> A suitable FIBC is selected for a particular application,

> Both liner and the FIBC meet the specifications of the testing requirements per the international standards,

> A permissible combination of a qualified liner and a particular FIBC is used,

References

IEC 61340-4-4 Edition 2.0: Standard test methods for specific applications – Electrostatic classification of flexible intermediate bulk containers (FIBC) 

Table 2