When such hygroscopic raw materials as rubber and plastic are used, process difficulties can occur in a humid atmosphere. Moulded products made of these materials can develop “air” pockets caused by stress; other imperfections can result from moisture adsorbed by the raw materials. In automobile production, it may be virtual impossibility to vulcanize tyre cord to rubber when the cord contains moisture. Dry Air used for storage and possibly in the production area can alleviate this situation.

The same sort of lumping and caking of powdered substances previously discussed is also a major problem in industrial chemical production. Some chemicals decompose in the presence of water vapor. In other situations, water vapor can actually cause a chemical
reaction that changes the character of the product.

Atmospheric moisture is also a natural enemy to many grinding and pulverizing operations. Water vapor in contact with the product can make it resilient and difficult to grind, causing it to cling to the grinding machine and defy pneumatic conveyance from one process area to another.

In marine and land-based applications, sandblasting removes surface damage and exposes the base material-often metal-that will receive a protective coating. Inside ships, or in underground or land-based storage tanks, a flow of dehumidified air on the newly prepared surfaces prevents rust or mildew formation while clean-up occurs and the coating step is prepared. Usually the dry air is forced inside the structure via normal ventilation lines.

Inorganic products are generally easier to dry than organic products because heat can be used as a drying agent. However, many inorganic compounds absorb large quantities of water. This is not water of crystallization- that is, it does not enter the lattice structure of the compound but it is nonetheless tightly held by the compound. When water of crystallization is involved, even the use of heat can be impractical… or damaging. But for most inorganic products, dry air may enhance operational efficiency and product quality.

Organic products are particularly challenging because of their high degree of affinity for water. Unfortunately, it is often impossible to use heat to release this water because heat can have a damaging effect. Dry, relatively cool air can be used to dry organic materials, but it must be circulated under varying velocities, and this creates the problem of special handling that is required with finely divided particles, for example.

Subcategories