Selection of Flexible Intermediate Bulk Containers (FIBC) and their relevance

Hey everybody! A big shout out to all the people who have helped me reach more than 1k viewers on the blog. Keep sharing with your friends, colleagues and to all others for whom you feel that this content will be relevant to.

The next concept which I have seen people struggling with is the selection of FIBC.

FIBCs are flexible, rectilinear containers constructed of woven plastic with a suitable liner. The typical FIBC is made of woven polypropylene with a polyolefin liner. Various designs exist for the basic container and grounding arrangements (if any), and larger capacities are also available.

There are four types of FIBCs which are available, i.e. Type A, Type B, Type C and Type D. Each of these have different specifications and different utilization & relevance.

Type A: Type A Bulk Bags are made from standard polypropylene insulating fabric. Static electricity is generated as products move over the inside surface of the Bulk Bag when they are being filled or discharged. Type A FIBCs are not intended for use in potentially explosive atmospheres.

P.S: Brush discharge are very unlikely to ignite pure dust clouds containing no flammable gases or vapors. However, a charged Type A bag holds the potential to charge the ungrounded operators and ungrounded metal items by induction; which can in-turn result in discharge leading to ignition of the dust cloud. Since charges generated are not dissipated, a significant amount of powder might get clung to the bag. This can result in wastage of powder and also results in a dust cloud and layer formation when FIBCs are being folded for disposal. Refer https://staub-ex.blogspot.in/2018/01/can-electrostatic-discharge-esd-from.html

Type B: Type B Bags are very similar to the Type A bags as they are made from the standard polypropylene material, and they do not have the ability to dissipate static electricity efficiently. The difference is that this type of bag has a low breakdown voltage (less than 4kV) to prevent propagating brush discharges (PBD) which are highly energetic and dangerous. Type B bags may be used in the presence of the combustible dust. However, they cannot be used in the absence of flammable vapors/ gases.

Type C: Type C Bags are constructed from non-conductive polypropylene material interwoven with conductive yarns that form a grid pattern, these are designed to control electrostatic charges by grounding. The bag MUST be electrically grounded during filling and emptying - this is essential to the safe use and performance of a Type C bag.

Type D: Type D Bags or antistatic Bulks Bags are constructed from an antistatic fabric which has antistatic or static dissipative properties to safely prevent the occurrence of incendiary sparks, brush discharges and propagating brush discharges and does not require grounding. These should not be used when the surface is contaminated or coated with conductive material such as water.

	Surrounding Atmosphere
MIE	Non Explosive	Explosive Dust	Flammable gas/ vapor (IIA/IIB) [For Example: Solvent Wet Powder]
MIE > 1000 mJ	A, B, C, D	B, C, D	C, D
1000 mJ > MIE > 3 mJ	B, C, D	B, C, D	C, D
3 mJ > MIE	C, D	C, D	C, D

FIBCs are often discarded after the first use, both for quality reasons and possible degradation of grounding elements. Examples of the latter include the erosion of aluminized conductive liners by product flow, and the breakage of metallic filaments during loading and handling cycles. FIBCs are fully collapsible for easy storage and once used can be folded again.

For FIBC manufacturers, different types of FIBCs have to be tested based on IEC standards.

Type B: Tested for breakdown voltage

Type C: Tested for resistance to ground

Type D: Discharge Incendivity Testing (certified if no ignition occurs during ignition testing)

Hope it will help you in understanding the type of FIBC required for your industry. Do like, share, comment and follow the blog. And you can always drop in your queries on himanshuchichra@gmail.com.