FIBC selection guide: type A, B, C and D big bags compared

Not every big bag is the same. The international IBC standard (FIBC = Flexible Intermediate Bulk Container) distinguishes four types based on their electrically conductive properties. The right choice prevents static discharge — a real risk with powders in combination with flammable gases or dust explosions.

Type A: non-conductive, no protection

Type A FIBCs are made of non-conductive polypropylene (PP). They offer no protection against static discharge and may only be used when:

The material is not flammable or explosive
No flammable gases or liquids are present in the environment

Suitable for: non-flammable powders such as sand, gravel, sugar (in a non-explosive environment). Lowest cost.

Type B: insulating but with low breakdown voltage

Type B resembles type A but is made of materials with a breakdown voltage of <6 kV. This prevents sparks with enough energy for dust explosions, but offers no protection against corona discharge or sparks that could ignite flammable gases. Use type B only when no flammable gases or vapours are present.

Type C: conductive and grounded

Type C FIBCs are made with conductive threads woven into a grid through the PP fabric. These threads are connected to a grounding point on the discharge or filling installation. Advantages:

Safe to use in the presence of flammable gases and vapours
Requires correct grounding — without grounding, type C offers no protection
Reusable provided conductivity is checked

Suitable for: flammable powders, pharmaceutical APIs, fine chemical powder. Requires a grounding protocol.

Type D: dissipative without grounding

Type D FIBCs are made of special dissipative PP fabric that discharges charge via corona discharge into the surrounding air — without grounding being required. Advantages:

No grounding cable needed (eliminates operator error)
Safe in flammable gas environments, provided the material in the bag is not conductive
Higher purchase price but lower operational risk

Suitable for: situations where consistent grounding cannot be guaranteed; high-value pharmaceutical or chemical applications.

Overview: which FIBC type to choose?

Type	Conductive	Grounding needed	Safe with flammable gases	Typical application
A	No	No	No	Non-flammable powder
B	No (low Vbd)	No	No	Dust explosion prevention, no gas
C	Yes (grid)	Yes	Yes (if grounded)	Flammable powder, pharma, chemistry
D	Dissipative	No	Yes	High-risk environments

Additional considerations in FIBC selection

Besides the type, the following factors also play a role in selecting the right big bag:

SWL (Safe Working Load): standard 500–2,000 kg, choose a minimum 5:1 safety factor
Inlet and outlet type: spout top, duffel top, fill spout bottom, discharge spout
Liner: PE liner for moisture protection or endless liner for contained handling
Codemax / UN certification: required for hazardous goods transport

Conclusion

The right FIBC selection is more than just choosing a bag. For flammable or pharmaceutical powders, the FIBC type determines the safety of the entire discharge process. Hecht Technology advises on the right choice and supplies discharge systems compatible with all FIBC types.

More info: Complete guide to big bag handling.