Type C conductive FIBC bags

What makes Type C FIBC bags conductive

Polypropylene is an insulator. As powder slides into or out of a plain bag, charge builds on the fabric and the product with nowhere to go. A Type C bag weaves conductive threads into the cloth, usually as a grid, and joins every section of that grid, across the seams, to a tab on the outside. Clamp the tab to earth and the charge drains away instead of building.

That last step is the whole design. Type B fabric works by limiting the kind of discharge the surface can produce and is never grounded. Type D fabric dissipates charge on its own without a ground. Type C does neither by itself; it is a conductor that needs a path to earth.

A plain polyethylene liner can put an insulating layer between the product and the conductive fabric, which undercuts the protection. If the product needs a liner, use one the bag maker has tested or approved as compatible with that Type C bag, and say so in the request so the pair is quoted together.

Type C FIBC grounding, step by step

Treat grounding as part of the fill, not something done after. Your site's procedure governs; this is the general shape of it.

• Look the bag over: label legible, ground tab present and undamaged, no cuts, scorch marks or snagged yarns in the fabric
• Hang the bag, then attach the grounding clamp to the tab before any product moves
• Check continuity from the tab to earth with a meter or the site's ground-monitoring unit, as the bag maker's documents describe
• Fill with the clamp attached; do not remove it to adjust the bag
• Close the top, and only then release the clamp
• Repeat at discharge: clamp first, check, empty fully, unclamp last

Never fill a Type C bag ungrounded

An ungrounded conductive bag is worse than a plain one. The threads collect charge from the whole bag surface and can release it as a single spark to a nearby object or person. That is precisely the event the bag exists to prevent.

So a missing tab, a clamp that has slipped, a cable worn through or a reading that fails all mean the same thing: stop, fix the connection, and recheck before product moves again. Many plants interlock the filler to a ground monitor so it will not start until the circuit proves good. Supervisors who audit that interlock regularly, and log each failed reading, catch worn hardware long before an incident.

The test methods and requirements for these bags sit in IEC 61340-4-4. Check that standard, NFPA 77 for your general static-control practice, and the bag maker's documents, and follow your site's hazardous-area assessment. We do not set those limits; we match the bag to them.

Shipping and storing conductive bags

Type C bags fold and bale like any other FIBC and ship on wrapped pallets, LTL or full truck depending on how many you need. Keep the bales dry and out of sunlight. When a bale is opened, check that tabs are intact and labels readable; a bag with a damaged tab goes aside and is not used.

Rough handling on a dock can kink or snap conductive yarns where nobody sees it, so careless unloading costs more here than with plain fabric. Forks pushed into a bale, a pallet dropped from a tailgate or bales left under a leaking roof all justify a closer look and a continuity check on a sample before the lot goes to production.

Your grounding kit at the filling station

The hardware is modest but it has to be right. A heavy-duty clamp with hardened jaws bites the tab firmly. A flexible, insulated, preferably coiled cable runs to a copper busbar or another point your electrician has confirmed is bonded to earth. Metal parts of the fill head, hopper, scale and frame are bonded too, because an isolated chute can charge up on its own.

Ground-monitoring units add a light or a relay that proves the circuit and can stop the feeder if the clamp falls off mid-fill. Whatever you use, inspect cables for fraying, clean corroded jaws, and write the checks into the operators' shift routine. Training matters as much as equipment: a newcomer who does not know why the clamp is there is the person most likely to skip it.

The bag is only one source of charge. People walking on insulating floors, plastic scoops, unbonded drums and dry winter air all add to the hazard. General static-control practice covers personnel grounding, such as dissipative footwear and floors, alongside the bag; your safety engineer decides which of those your area requires.

Type C, Type B or Type D

The choice belongs to your hazardous-area assessment, not to price. Plants often favour Type D where operators rotate frequently or grounding discipline is hard to sustain, and keep Type C where clamps and monitors are already installed and audited. As a broad guide, here is how the three static types differ in use.