Archive for April, 2009

Dunnage Bag Terms

April 24, 2009

Common Terms Used In Dunnage Bags
AAR                                                           American Association of Railroads
Air Bladder                                            The inner plastic bag holding the air . Also called liner.

Burst pressure                                      The pressure beyond which the bag may burst

Crosswise bracing                               The dunnage bag is installed with the length parallel to the floor

Deflate                                                      Air is released from the inflated bag

Effective contact area                       The area of the bag directly in contact with the cargo loads or walls. The inflated bag

                                                                    is rounded at the top and bottom so only the central portion is in contact with the

                                                                    cargo load 

Force                                                        The force generated by the inflated dunnage bag. It is proportional to the effective
                                                                     contact area and the inflation pressure.

Gap                                                            See void

GSM                                                          Refers to the weight in gram per square metre of the kraft paper or polywoven fabric

Inflate                                                      Fill the bag with compressed air

Install                                                      Place and inflate a bag in a void

Kraft paper                                            Special paper used to make the outer bag

Laminated paper                                Refers to kraft paper laminated with layer of polywoven fabric

Layer                                                       The number of separate layers of material making up the bag

Leak                                                         The inflated bag losing air over time

Lengthwise bracing                           The dunnage bag is placed with the length perpendicular to the floor

Level 1                                                    AAR classification of dunnage bag with working pressure of 2.5psi and burst pressure

                                                                   of 8psi 

Level 2                                                   AAR classification for dunnage bag with working pressure of 5psi and bust pressure of 


Level 3                                                   AAR classification of dunnage bag with working pressure of 8psi and burst pressure of


Level 4                                                 AAR classification of dunnage bag with working pressure of 10psi and burst pressure of


Liner                                                     See air bladder

One-way valve                                 The valve only allows compressed air to enter the bag but not out of it.As such, the bag

                                                                can only be inflated once.

Paper dunnage bag                        A dunnage bag with a paper outer bag

Ply                                                        Refers to the number of separate layers of paper in the outer bag

Polywoven dunnage bag             A dunnage bag made with a polywoven outer bag

Recyclable                                        The material making up the bag can be recyled into raw material for reuse.

Reusable                                           The bag can be used 2 or more times

RoHS                                                  This refers to the European Union directive on Restriction on use of Heavy Metal


Size of bag                                         Refers to the length and width of the uninflated bag

Two-way valve                               The valve allows compressed air to be pumped into the bag and also allows the air

                                                               inside the bag to be released . This means the bag is reusable.

Void                                                     The empty space between cargo loads or between the cargo load and the wall where the

                                                               dunnage bag is installed.

Working pressure                          The  pressure that the bag can be safely inflated to.

WPP fabric                                         Woven propylene fabric is woven from polypropylene yarn