When filling and emptying big bags, static electrical energy can be discharged, which can lead to an explosion in an explosive environment. Depending on the structure, conductivity and determinations, big bags can be divided into several groups according to the IEC 61340 standard:

 

BIG BAG Typ-A -  FIBCs made from non-conductive materials without any measures against electrostatic charging. As no electrical conductive material is interwoven in the fabric grounding and charge dissipation is hardly possible. Explosive atmospheres of gases as well as explosive atmospheres of dusts can be ignited. Therefore, a Type A FIBC must not be used to handle combustible dusts. If such a FIBC containing inert material has to be used in hazardous areas, this may only happen in zones 2 or 22.

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BIG BAG Typ-B -  FIBCs made from non-conductive materials having a breakdown voltage not exceeding 6 kV. This reliably prevents the ignition of explosive dust atmospheres while explosive gas atmospheres can still be ignited. Like Type A, the Type B has no interwoven conductive materials. Thus, a Type B FIBC can be used where combustible dusts are present, but it shall not be used in hazardous areas, zones 1 or 0.Type B FIBC are permitted in Dust Zone 21-22 with MIE > 3 mJ (MIE = Minimum Ignition Energy).

 

BIG BAG Typ-C - FIBCs normally made of non-conductive fabric with interwoven conductive threads

• forming a reliably interconnected grid of maximum 50 mm mesh size
  or

• having a distance between each other of less than 20 mm if the threads are in one direction only.

 

Those conductive threads must be interconnected with less than 107 ohm and must be grounded during filling and emptying operations. Some Type C FIBCs have interconnected conductive loops to enable grounding via a (grounded) hoist system. When grounded properly there is no risk of incendive discharges.
The inner or outer surfaces of the FIBC may have a thin coating. In this case the breakdown voltage to the conductive threads must not exceed 6 kV to avoid propagating brush discharges.
Thus, Type C FIBCs can be used in an environment with combustible dusts and/or explosive gases. There is no risk using these FIBCs in hazardous areas zones 1, 2, 21, 22, providing they are properly grounded.