Blue indicating silica gel is impregnated with cobalt chloride which changes from blue to pink as the desiccant becomes saturated. With the introduction of a European directive, cobalt chloride impregnated silica gel has been classified as a carcinogen. Therefore the handling and disposal of this desiccant must conform to relevant health and safety, and special waste regulations.
Envirogel desiccant is the latest alternative to blue indicating silica gel. Envirogel is impregnated with a safe organic indicator which displays an orange/yellow colour when active and changes to green when the desiccant becomes saturated.
As with non-indicating silica gel it can adsorb approximately 30% of its own weight of water from the surrounding atmosphere at 50% RH at normal temperatures.
Blue indicating Silica gel is produced in granular and beaded forms. The beaded form has a higher mechanical strength than the granular type and therefore less likely to generate dust. Also, the uniform bead size reduces gas flow channelling and minimizes pressure drop.
The desiccant may be reactivated for re-use by heating. However, after several reactivation cycles the material may disintegrate into powder. This in turn, reduces the adsorption capacity of the material. Please contact us for the specific reactivation procedure.
The adsorption capacity of silica gel can be destroyed by contamination with dust, grease or petroleum products, and also by heating the material above 120°C.