Type D FIBC bulk bags

How the fabric gets rid of charge

Type D fabric has static-dissipative yarns woven through it. As powder charges the bag, those yarns release the charge into the surrounding air in small, low-energy discharges rather than letting it collect to a level that could ignite something. No ground cable is part of that process. The bag handles it on its own, at the filler, on the forklift and over the hopper.

Type B prevents one dangerous discharge and leaves the rest of the charge alone. Type C drains it through a cable that a person has to connect. Type D sits apart from both, which is the whole reason buyers choose it.

Nothing in the operator's routine changes from a plain bag: hook the loops, clamp the spout, fill, tie, lift and discharge. The difference is a step that isn't there.

Testing under IEC 61340-4-4 is what earns the Type D mark, and the maker's records show which lot was tested. Those papers, not a glance at the yarns, are your proof of type.

Why sites skip the ground clamp

A Type C bag is only as good as the last person who connected its cable. On a busy line with shift changes, several discharge points and bags moved between rooms, that is a lot of clamps to get right every time. Taking the cable out of the procedure removes a step that can be missed.

That doesn't make Type D a universal answer. Where it can be used is set out in IEC 61340-4-4 and the maker's documents, and the final call belongs to your site's hazardous-area assessment. If the assessment names Type C, buy Type C and enforce the ground.

• No ground cable to connect or check at each station
• Bags can move between rooms without a new procedure
• Plant equipment, people and metal parts still need grounding and bonding
• Use stays limited to what the assessment allows

Storage, liners and keeping it as built

The fabric only behaves as tested if it stays the way it left the maker. Store bales indoors, dry, out of sunlight and off the floor. Check the maker's documents on handling and on anything that could coat or contaminate the fabric.

Liners need the same care as with Type B: use only a liner the maker has assessed with that bag. Don't repair a damaged Type D bag, and don't add labels, patches or ties the maker didn't supply.

Damage is a reason to retire the bag, not mend it. Cuts, fork abrasion, scorch marks and torn loops all turn a bag into something other than what was tested. Set it aside for recycling with the rest of your empties.

Unheated warehouses bring their own issues: condensation when cold bales come into a warm plant, and forklift scuffs on the outer layer. Let bales acclimatize before opening them, and break the strapping with a safety cutter rather than a knife that can nick the top bag.

Bales, pallets and new-only supply

Type D bags ship folded and baled on wrapped pallets, like any other bag. A pallet or two ships LTL, and steady users often take a full trailer to cut the freight per bag. We quote static-protected bags new only, and every order keeps its lot paperwork with the bales so you can match bag to documents on receipt.

When the truck arrives, pull a sample bag from each bale, check its label for the Type D mark and the lot number, and file the documents. Segregate these bales from plain stock, since a Type A bag looks much the same, and rotate the oldest lot forward so nothing ages forgotten in a corner.

Putting the Type D request together

Start with the assessment's answer, in writing if you have it. Then the product, whether it's dry, the spout sizes, any liner, the SWL and the monthly count, and the ZIP of the plant. We match the bag to that spec, plan the pallets and the truck, and confirm a delivery date with the carrier.

Moving over from Type C? Leave the existing cables and clamps in place until the assessment is revised, then update the written procedure so every operator knows which bag needs a cable and which doesn't. Mixed stock on one line is where confusion starts.

A sample before a full order is sensible whenever a plant changes type. Engineering can check the label, file the certificates and run a supervised trial fill before the procedure is rewritten.