Mục lục
Reviewed and updated by ICD - Week 24/2026
Quick summary:
- Using a dunnage bag correctly follows 5 steps: assess the void, protect sharp edges, position the bag, inflate to the right pressure, and check/deflate.
- The ideal void for container bags (kraft, woven PP) is 10-40 cm. Over 50 cm, narrow it with rigid filler first; under 5 cm, use another material.
- The most common failure is the bag tearing on a sharp edge - always pad edges with cardboard or plywood.
- Inflate to the rated working pressure (about 0.2 bar for Level 1) - firm but still elastic, never rock-hard.
Preparation: the key to performance
Before bracing, identify the bag type and match the inflation gear. For container bags (kraft, woven PP), use a dedicated compressed-air gun; for in-box PE/LLDPE bags, use a mini electric pump - never industrial compressed air. For the basics, see what a dunnage bag is.
Respect the max-void rule: the ideal void is 10-40 cm. Over 50 cm, the bag over-rounds into a sphere, cutting contact area by up to 50% and almost nullifying its bracing - narrow the gap with rigid filler (a pallet, thick cardboard divider) first. Under 5 cm, it cannot build pressure - use another material. Keep kraft bags dry before use, and pre-cut padding boards to size to shield sharp edges.
The 5-step process for container bags (kraft and woven PP)
Step 1 - Pad and protect sharp edges: the mandatory step that prevents tearing, the most common cause of failure. Place thick cardboard or thin plywood wherever the bag will touch the sharp corners of a wooden pallet, metal box or machinery. Padding guards against two risks: puncture from a hard hit on a corner, and abrasion as constant vibration rubs the edge against the bag.
Step 2 - Position the bag: set it upright in the center of the void, not twisted or folded. Its height must cover at least 2/3 of the load height; too low, and the upper load can topple when the container sways because the top is not locked.
Step 3 - Connect the gun and control pressure: use a dedicated gun with a pressure gauge. Inflate to the maker’s working pressure, typically 0.2 bar (2.9 PSI) for a Level 1 kraft bag. Do not inflate rock-hard - the bag needs elasticity so that when the load surges it compresses slightly, converting kinetic energy to heat and absorbing the shock. A too-hard bag transmits the impact straight into the goods.
Step 4 - Check the valve and lock the air: after reaching pressure, withdraw the gun; the valve auto-locks, then tighten the cap for a complete seal. See our dunnage bag valve guide.
Step 5 - Inspect and deflate at destination: inspect mid-journey if possible. At the destination, deflate before removing the load - on woven PP bags the valve releases air for reuse; kraft bags are disposed of or recycled.
Using in-box air bags (PE/LLDPE)
For small voids inside a carton, inflate a soft PE/LLDPE bag with a mini electric pump to a low pressure, just enough to cushion and stop single items moving. These do not brace a container load and carry no AAR rating.
Frequently Asked Questions (FAQ)
Why must I pad sharp edges?
Sharp edges puncture or abrade the bag - the most common cause of failure. Cardboard or plywood spreads the force and protects the shell.
What pressure should I inflate to?
The maker’s working pressure, about 0.2 bar for Level 1. Firm but elastic - never rock-hard, which transmits impact into the load.
What if the void is over 50 cm?
Narrow it with rigid filler first; do not use one over-stretched bag, which over-rounds and loses contact.
Can I reuse the bag?
Woven PP bags deflate and reuse many times; kraft bags are single-use and recyclable.
Contact ICD Viet Nam
For dunnage bags, inflation guns and on-site guidance, contact our team for a quote.
- Northern Vietnam: 0983 797 186 / 090 345 9186 / 090 5859 186
- Southern Vietnam: 098 6784 186
- Email: sales@icdvietnam.com.vn
- Zalo: Chat on Zalo
