Standard four-loop big bags

A standard big bag is a flexible intermediate bulk container (FIBC) with a woven polypropylene body, a bottom, four walls and four corner lifting loops, and no special-purpose feature. It is the most common bulk bag on the market and the type DIV Trades produces in the largest numbers at its plants in Bačka Palanka, Serbia. A standard four-loop big bag typically holds 1 to 2 m³ and carries a safe working load (SWL) of 500 to 2,000 kg.

Standard does not mean off the shelf. Every bag is made to the customer's specification: dimensions, fabric weight and coating, dustproof sewing, inlet, outlet, loops, printing and document pocket. A small range of common sizes is also available from stock.

How a standard big bag is constructed

• Body: woven polypropylene fabric, usually 165, 180 or 200 g/m² depending on the SWL and safety factor, white as standard, with 150 kly UV stabilization.
• Coating: optional 30 g/m² polypropylene coating that makes the fabric waterproof and stops fine material sifting through the weave.
• Loops: four PP raffia or multifilament loops, 40 or 50 mm wide, sewn into the corners with a free height of 25 or 30 cm (60 cm when all four loops must catch on one hook).
• Seams: sewn without sealing strips for granular goods, or with one, two or three sealing strips for fine materials.
• Label and extras: every bag carries a label stating SWL and SF; an A4 document pocket and printing on up to four sides are optional.

When to use a standard four-loop FIBC

Use a standard big bag for any free-flowing bulk material that does not need antistatic protection, food-contact measures, UN approval or ventilation: sand, gravel and construction materials, plastic granules, grain, seeds, animal feed, fertilizer, pellets and recycled materials. Forklift handling at the filling station and the customer's site is all it requires.

When the product or the process needs more, DIV Trades builds the same four-loop body as a special construction or a special-purpose bag:

• Formstable (Q-bag): baffles keep the bag square and save up to 25% of space.
• With inliner: a PE liner for the highest dustproof level and moisture protection.
• One or two loops: lifted by hook without a forklift, the most economical bag per kg.
• Foodclean: produced under HACCP and ISO 22000:2018 for direct food contact.
• Conductive Type B or C: for flammable products and explosive atmospheres.
• UN bag: tested and certified for dangerous goods of packing groups II and III.
• Ventilated: breathable fabric for potatoes, onions and wood.

Top and bottom options for standard big bags

These are the inlet and outlet types ordered most often for standard bags. All variants, including flap, conical top, umbrella, rosette and star closures, are described under filling options and discharging options.

Open top

The simplest and cheapest inlet. Easy to fill by hand or machine, but the goods are not protected from weather or dirt.

Inlet skirt

A fabric skirt with ties closes the whole top. Protects the product well and needs no automatic filling machine.

Inlet spout

A spout of 30-50 cm diameter and 50 cm length in a closed top. Dust-free filling on a filling machine and the best protection for the material.

Flat bottom

Fully closed bottom; the bag is emptied by cutting or tipping. The cheapest outlet, common for construction materials and waste.

Outlet spout

The standard outlet: a 25-65 cm spout with a tie, swan-neck closure or B-lock for controlled discharge.

Typical dimensions and loads

The most common external base is 91 × 91 cm for 1,000 kg and 95 × 95 cm for 1,200 or 1,250 kg, which loads a standard truck to 24 or 25 tonnes. Heights run from 50 to 250 cm and should not exceed twice the shorter side. Stock items such as 91 × 91 × 130 cm and 91 × 91 × 155 cm with SWL 1,000 kg at SF 5:1 cover many applications; see dimensions and SWL and SF for the full picture.