CAL-IN's line of desiccant dehumidifiers are effective in controlling humidity at low temperatures, and have been widely applied to prevent moisture regain.



Moisture Regain Prevention

Virtually every substance has some affinity for moisture. Even plastic resins like nylon can collect six to ten percent of their dry weight in water vapor. In many cases, this presents no problem. In others, moisture regain can affect critical dimensions just like thermal expansion, or make products that would otherwise flow freely, stick together. The typical home salt shaker illustrates this point—moisture regain on humid days clogs the shaker holes. On a dinner table, this may be a minor problem. But in packaging machinery, sticky products have major economic consequences.

Hygroscopic products are sensitive to high relative humidities rather than absolute humidities, and relative humidity can be high at any time of year. In fact it is often higher in winter than summer. When products are stored at cool temperatures, problems can be especially acute.




Candy Packaging

Hard candies often contain corn sugars and sorbitol, both of which are highly hygroscopic. When humidity is high, the product can absorb moisture and become sticky. Then it sticks to packaging machinery and wrapping material, slowing the process and creating sanitary problems. Desiccant dehumidifiers are used to keep packaging areas dry, letting equipment run efficiently and reducing the cost and time required for equipment cleaning.



Semiconductor and Pharmaceutical Clean Rooms

When microcircuits are manufactured, hygroscopic polymers called photo resists are used to mask circuit lines for etching processes. These polymers are hygroscopic. If they absorb moisture, microscopic circuit lines are cut or bridged, resulting in circuit failure. In pharmaceutical manufacturing many powders are highly hygroscopic. When moist, these are difficult to process and have limited shelf-life. For these reasons and others, clean rooms are equipped with desiccant dehumidifiers, which prevent moisture absorption, allowing fast manufacturing of high-quality products.



Safety Glass Laminating

The thin, transparent plastic film which serves as the adhesive between layers of safety glass is quite hygroscopic. If allowed to absorb moisture, the film will boil it off in processing, creating steam bubbles which get trapped in laminated glass. Desiccant dehumidifiers create low-humidity environments for the manufacturing, storage and use of this laminating adhesive.




Advance Composite Manufacturing

Many uncured epoxy resins have a high affinity for moisture. When they absorb water vapor, the molecular sites which would otherwise cross-link to form strong bonds are blocked by water molecules. This slows down curing until the wetter is evaporated, or results in low strength parts. Printed circuit boards, filament-wound aerospace parts and pre-impregnated synthetic materials are all manufactured and stored in low-humidity environments to speed processing and improve product quality by preventing moisture regain.

TYPICAL APPLICATIONS

• Biomedical dry rooms
• Fertilizer packaging & storage
• Pharmaceutical tableting
• Foundry core storage
• Powdered drink mix packaging
• Plastic resin storage
• Instant coffee processing
• Sealed lead-acid batter filling
• Pre-preg material storage
• Paper storage
• Flour, plastic and powder airveying
• Sugar storage & packaging
• Epoxy powder manufacturing
• Pharmaceutical packaging
• Vitamin tableting & packaging
• Circuit board storage & machining
• Photolithography operations
• Precision color printing
• Cork storage
• Candy tableting & packaging
• Dried vegetable storage
• Propellant mixing & casting
• Missile motor storage
• Contact lens machining
• Filament winding
• Lens coating
• Veneer storage
• Power cable jointing
• Insulation for cold tanks
• Fruit powder handling
• Chewing gum ripening rooms