Indicating Drierite, Anhydrous Calcium Sulfate, 4 Mesh, 25 lb. W.A.Hammond 21025

W.A. Hammond® Indicating Drierite®, Anhydrous Calcium Sulfate, 4 Mesh, 25 lb., 21025

Features:

• Impregnated with cobalt chloride — blue when dry and changes to pink upon absorption of moisture
• Color change is pronounced and clearly visible — valuable when it is necessary to know with certainty that dryness is being maintained and to signal when drying agent should be replaced
• Cobalt chloride also increases effectiveness of desiccant over plain desiccant because of its own desiccating effect
• Can be regenerated!
• For regeneration of desiccant, granules may be spread in layers one granule deep and heated for 1 hour at 210 °C (425 °F)
• Regenerated material should be placed in original glass or metal container and sealed while hot
• Color of desiccant may become less distinct on successive regenerations due to migration of indicator into interior of granule and sublimation of indicator
• Temperature at which desiccants are regenerated is crucial in restoring Drierite® to its original condition
• Absorbed moisture is water of hydration and is chemically bound to calcium sulfate of Drierite® — temperatures in range of 400° to 450°F are required to break these bonds and release absorbed moisture; lower temperatures, regardless of heating time, will not regenerate Drierite® unless applied under vacuum (26 in. Hg., 325 °F or 28 in. Hg., 275 °F). 

Note:

• Care should be take not to overheat desiccant since high temperatures can alter crystal structure and render desiccants permanently inactive