The crude vegetable oil from above mentioned two ways of extracting, oil pressing and/or solvent extraction, will be pumped into oil refinery unit to produce cooking oil at various grades. The main equipment of oil refinery is various kinds of pot and tanks carrying on different tasks with additives. These tasks may include sedimentation/filtering, neutralization (removing free fatty acid), degumming, decolorization (bleaching), deodorization, dewax etc. Different combination of steps and the treating degree of each step result in different grade cooking oil and salad oil.