Static Happens: Electrostatic Hazard Classifications of FIBCs
If you’re looking for Flexible Intermediate Bulk Container bags (FIBCs), the first step before you select is critical: ensuring the electrostatic hazard classification of the bag(s) you are considering using is appropriate for the bag’s contents and surrounding environment. If you overlook this step, property damage and injuries may result.What’s in a Bag?
Flexible, woven fabric bags (FIBCs), made from polypropylene, have countless industrial applications across many industries. Agriculture, construction, food processing, chemical manufacturing, and mining are just a few. FIBCs are typically used for storing, handling, and transporting dry, flowable products such as grains, chemicals, fertilizers, plastics, sand, and various construction materials.
Static Happens
When the contents of a polypropylene bag move around and rub against the sides of the bag, whether during fill, transport, or discharge, friction between the contents’ particles and the bag’s inner surface generates electrostatic charges. This process is called triboelectrification. The insulating nature of polypropylene prevents the electrostatic charge from dissipating, resulting in static buildup on the product and the FIBC bag.Four Types of FIBC Bags: A, B, C, and D
Here is a breakdown of the fundamental differences between the four types of FIBC bags, from least or no dissipative qualities (A) to most dissipative (D), and the fabric requirements of each:- Type A FIBCs are made from non-conductive materials without any built-in mechanism for controlling and dissipating static electricity. Type A bags should only be used in non-flammable atmospheres.
- Type B FIBCs, similar to Type A FIBCs, are manufactured using non-conductive materials without any built-in mechanism for controlling and dissipating static electricity. Type B FIBCs are manufactured from materials with a low breakdown voltage and are designed to prevent propagating brush discharges from occurring during the normal handling process. Type B FIBCs can be manufactured using uncoated fabrics or fabrics with a thinner laminated coating, requiring a breakdown voltage of < 6kV.
- Type C FIBCs are manufactured from conductive fabric or non-conductive fabrics interwoven with conductive yarns that form a grid within the FIBC framework. The conductive fabric and yarns must be interconnected with an RG<108ohms, and the FIBC must be grounded during all filling and emptying procedures.
- Type D FIBCs manufactured using CHROMIQTM technology use non-conductive fabrics interwoven with quasi-conductive fibers located approximately 20mm apart in the warp direction of the fabric. The interwoven fibers safely and effectively dissipate the static electrical charge into the surrounding environment through a low-energy corona discharge. FIBCs manufactured with CHROMIQTM fabrics do not need to be grounded during the filling and discharging process.
| MIE of Dust |
Non-Flammable Environment |
Explosive Dust Environment |
Explosive Gas and Vapor Environment |
| MIE > 1,000 mJ |
A, B, C, D |
B, C, D |
C, D |
| 1,000 mJ ≥ MIE > 3 mJ |
B, C, D |
B, C, D |
C, D |
| MIE ≤ 3 mJ |
C, D |
C, D |
C, D |
FIBC Bulk Bag Labeling Requirements
Along with specific fabric requirements, Type B, Type C, & Type D FIBC bags have labeling requirements per the IEC 61340-4-4 standard. Labels should be yellow with black lettering, making them easy to read. Additionally, the label material and the bag liner, if any, must adhere to its electrostatic hazard classification standards.FIBC Bulk Bag Liner Classifications
If a bag has a liner, the liner must also meet safety standards for use around static electricity. There are four liner classifications: L1, L1C, L2, and L3. Each liner type is only compatible with certain FIBC bag types. See the table below for details.|
FIBC Type |
L1 Liner |
L1C Liner |
L2 Liner |
L3 Liner |
| Type B | NO | NO | YES | YES |
| Type C | YES | YES | YES | NO |
| Type D | NO | NO | YES | NO |