Most manufactures are aware of the hygroscopic behaviour of polyurethane and ensure that its moisture content is controlled during storage. This polymer has a natural affinity with moisture, therefore tends to attract water vapour from the surrounding air. The chemical reaction resulting from this process breaks the long chains of the polymer affecting the quality of the products manufactured using the short chains.

Brownell's Drum Vent Dryer is available in different sizes, suitable for 205L/ 55 gallon drums and 1000L containers. 

The dryer is filled with environmentally friendly silica gel – Envirogel – which is said to be capable of adsorbing moisture up to 30% of its weight. The desiccant colour change from orange to green signals that the desiccant is saturated and needs to be replaced.