Dunnage Bags & Inflators

Why void filling matters

Load securing works through form-locking and force-locking. Dunnage bags are the fastest way to achieve form-locking inside a container: by filling the gap between load units, the cargo and bags together fill the space completely, so the container walls and doors absorb the forces of a shifting load instead of the cargo absorbing them itself.

A gap of 20 cm is enough for a pallet to build damaging momentum over a long sea voyage. Filling it costs a few euro; the damage it prevents can run into thousands.

Choosing size and pressure

• The bag should fill the gap when inflated, not be forced into it. Measure the void and select the size that covers it comfortably.
• Larger voids call for larger bags rather than several small ones stacked, which can slip past each other in transit.
• Never exceed the fill pressure printed on the bag — over-inflation is the most common cause of failure.
• For heavier or longer transits, use a higher-rated bag rather than over-inflating a lighter one.

Inflation in practice

Bags fill from a normal compressed air line using a fill gun. Venturi-type valves draw in ambient air alongside the compressed air, filling substantially faster and using less compressor capacity. Fill guns fit standard air hose couplings. Inflate to the rated pressure, check the bag sits square in the void, and confirm it stays in position when the load is nudged. Deflate through the valve for reuse rather than cutting the bag.

Placement rules

• Place bags between load units, not between cargo and the container door — pressure against a door makes unloading dangerous.
• Keep bags clear of sharp edges, protruding nails and steel banding; combine with edge protection where cargo corners are sharp.
• Use a cargo bar or load bar at the door end so the load cannot fall out when doors are opened.
• Position bags at load height, centred on the mass of the cargo rather than at the very top or bottom.

Reuse and cost per trip

Level 1 woven polypropylene bags are designed to be deflated and reused across multiple shipments provided they are undamaged. That is what makes the pallet price decisive: the cost per bag drops sharply at pallet quantities, and each bag then serves several loads. For an operation stuffing containers weekly, the real cost per trip lands far below the single-unit price most suppliers quote.

Frequently asked

Which size do most operations use? Mid-range sizes cover the majority of pallet gaps in 20ft and 40ft containers, but the right choice depends on your pallet pattern. Send us your loading plan and we advise.

Can they be used in reefer containers? Yes — the outer polypropylene resists chemicals, alkalis and acids and performs in refrigerated and frozen containers as well as in high humidity and extreme temperatures.

Do I need a special inflator? A standard compressed air supply plus a matching fill gun is sufficient. Valve type determines which gun fits, so order the gun that matches your bags.

For volume pricing or advice on bag size for your loading pattern, contact info@sorbpack.com.

▲ Read less