MINIMIZING UNLOADING TIME (CON’T.) 3. The relaƟve density (product to air raƟo) decreases as the elevaƟon increases. The higher the storage fa- cility, the longer it will take to unload. The graphic below illustrates the relaƟve density at various elevaƟons. Note that as the product head (back) pressure decreases, the air velocity will increase and air pressure will decrease.
RelaƟve Density at Various ElevaƟons
4. Heavy, fine materials such as sand or sugar require considerably more unloading Ɵme. Light, bulky prod- ucts offer more resistance and are more easily carried by the air stream. Use the pressure control valve and the product discharge valve to maintain the opƟmum product-to air raƟo for the type of product being un- loaded.
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