The flask is an integral piece of equipment to the synthetic organic or medicinal chemist at lab scale; however, on large scale the flask is uneconomical. The bulk chemical, petrochemical and polymer industries all opt for the use of pipes as the reaction vessels of choice, allowing them continuous operation and enhanced control over reaction conditions. The pharmaceutical and fine chemical industries, on the other hand, frequently use continuous stirred tank reactors (CSTRs) to perform their reactions. The reason for the disparity of approach between these industries is that in the pharmaceutical industry, process development occurs incrementally over a number of years beginning with milligram scale and increasing successively by several orders of magnitude up to a scale of tons, as required.  As such, scale up in the pharmaceutical industry is carried out by gradual increase in the size of the reactor rather than performing a costly and time-inefficient redesign of a process.