It removes the source of contamination. For example, heating metals to high temperature causes rapid oxidation in regular ovens which is undesirable. It reduces the heat loss which is caused by convection In chemical process industries like food, pharmaceutical, agricultural, textile, paper & pulp etc. drying is an essential unit operation to remove the moisture from various substances to get a solid finished product .Vacuum drying is generally used for the drying of those substances which are hygroscopic and heat