A pumping system that is used to supply fluids to a process from time to time. They often form part of a control system such as the need to maintain the pH in a bioreactor with the controlled addition of acids and alkalis. Other dosing examples include chlorine dioxide being added to drinking water and power station water, and chlorine gas for swimming pool disinfection. Peristaltic pumps are often used for small systems such as laboratory bioreactors, and diaphragm pumps for larger applications.