Table of Contents
Reviewed and updated by ICD - Week 29/2026
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
Dunnage Bag Inflation Parameters by Size
Inflation pressure and gap capacity vary significantly by bag dimensions. Using the wrong pressure for a given bag size is the single most common cause of premature failure - either a burst bag from over-inflation or inadequate void fill from under-inflation. The table below gives the working parameters for the four standard sizes distributed by ICD Vietnam, based on manufacturer specifications from our air dunnage bag range.
| Bag Size (mm) | Inflation Pressure | Typical Gap Fill | Inflation Time |
|---|---|---|---|
| 600 x 900 | 0.4-0.7 bar (6-10 psi) | 7-12 cm gap | 20-30 sec |
| 600 x 1500 | 0.5-0.8 bar (7-12 psi) | 10-18 cm gap | 30-45 sec |
| 900 x 1800 | 0.6-1.0 bar (9-15 psi) | 14-22 cm gap | 40-60 sec |
| 1200 x 2400 | 0.8-1.2 bar (12-17 psi) | 18-24 cm gap | 50-80 sec |
Always check the maximum rated pressure printed on the bag label before inflating. Exceeding that limit - even briefly - can cause the inner bladder to separate from the outer kraft paper sleeve, leading to sudden deflation during transit. For gaps wider than 24 cm, place two bags side by side rather than over-inflating a single bag.
Frequently Asked Questions
What air pressure should I use to inflate a dunnage bag?
Most dunnage bags are inflated to 0.4-1.2 bar (6-17 psi) depending on size. Do not exceed the maximum rated pressure printed on the bag or specified in the technical sheet. Smaller bags in the 600 x 900 mm range operate at the lower end of that range (0.4-0.7 bar), while larger 1200 x 2400 mm bags require more pressure (0.8-1.2 bar) to achieve full contact with both cargo faces. Using a regulator on your compressed air line is the most reliable way to stay within the correct range - free-flow inflation from an unregulated hose frequently causes over-pressurization, particularly with smaller bags where the bladder fills very quickly.
How do I know the dunnage bag is properly inflated?
The bag should feel firm when pressed with your palm - similar to a car tire at low pressure. It should fill the gap completely without visible sagging, but should not be so hard it cannot flex slightly when you push against it. A correctly inflated bag maintains full contact with both cargo walls along its entire surface, with no visible gaps at the edges. If the bag is drum-tight and cannot be compressed at all with hand pressure, it is likely over-inflated - release pressure through the valve until it returns to firm-but-flexible. If the cargo can still shift when you push it by hand after installation, add pressure in 0.1 bar increments until movement stops.
How long does it take to install one dunnage bag?
Installation takes 2-5 minutes per bag including positioning and inflation. An experienced worker can complete a 20-foot container in under 30 minutes using 4-6 bags, depending on load configuration and gap count. The largest share of that time is cargo positioning before the bag goes in - the actual inflation step is only 20-80 seconds depending on bag size. First-time users typically take longer because they are calibrating the feel of correct inflation; after 10-15 bags the process becomes routine. For high-volume operations handling 20 or more containers per day, a dedicated inflation tool with a built-in pressure gauge cuts per-bag time to under 60 seconds consistently.
