Disposable Dunnage Bags

Checkstow is the Future
The new Checkstow dunnage air bag is designed for heavy duty use in the toughest conditions. The 1600 denier woven polypropylene outer gives this bag a clear lead in strength, resistance to water and value for money compared with other materials, while the high density polythene liner ensures long term air retention and the possibility of re-use.

Applications
Checkstow is used for all types of cargo where a low cost airbag is required. It is equally suited for maritime breakbulk cargos, container dunnage, and road or rail transport. Checkstow Heavy Duty is able to match all dunnage requirements where value and strength are the priorities.

Design
Checkstow follows the well established engineering principle which says “the simpler the better”. The outer re-enforcement layer of 1600 denier slit polypropylene is tubular woven and folded and sewn at the ends with polyester cloth re-enforcement. This results in an outer layer of high strength with excellent puncture resistance. Air is retained by the high density 125 micron polythene inner which is co extruded and blow moulded with welded ends. The simple valve assembly is welded in place and accepts standard air guns. Deflation is rapid – simply unscrew the valve. Optimised materials make a highly cost effective, re-usable bag.

Heavy Duty Strength
The load an air bag can withstand depends on the strength of material used, quality of construction and the size of gap between the goods which it is used in. The narrower the gap, the less stress on the airbag, so the higher the pressure it will withstand and thus the greater the load. Also, the greater the contact area of the bag with the goods the better because this allows the pressure in the bag to
be exerted on the goods rather than “wasted” stressing its own material. It follows that in a narrow gap the contact area will be greater than in a wide one, so the airbag will be more effective.

This is illustrated in the performance table for a 90 cm x 180 cm Checkstow:


The force available depends on the gap – the smaller the gap the better the level of protection against movement in tough conditions.

Airbag Sizes and Weights
Standard sizes are 90 cm x 180 cm, weighing 1.04 kg and 90 cm x 120 cm weighing 0.69 kg. Special sizes are available for large orders.

Working Pressure
Strong materials allow a safe working pressure of 0.3 bar (3 psi). This ensures there is enough safety margin to allow for changes in ambient temperature. Increases will make the airbag pressure go up and decreases will make it go down. Checkstow’s heavy duty construction allows a margin of safety not possible with other bags which risk bursting as temperatures increase or getting too soft as
they decrease.

The forces available can be very high. Consideration must be given to whether the cargo and
packaging can withstand the inflation pressure chosen.

Valves
Checkstow’s re-usable valve is designed to be simple and effective. It can be used with a variety of filling guns. Our own gun is available if required. Letting air out could not be easier, just unscrew the valve core. This encourages re-use.