The initial financial investment in the establishment of continuous installations is generally higher than that of batch installations. This is due to the automated control systems and despite the fact that the reactors in the batch installation are bigger. As a result of economic and technological considerations, products required in large quantities and for which there is a year-round demand, are usually manufactured in continuous installations. On the other hand, in the case of materials required in small quantities, or alternatively, for which the annual demand varies, it is unfeasible to build a continuous system. Production processes in chemical industry plants are often planned so that certain sections are continuous while others use the batch method. Planning of this kind is also derived from technological and economic considerations.