How many types of dosing pump?

There is electronic pumps and mechanical pump. Electronic pumps are run using an electronic EPU assy. mainly used outdoors because it does not need to have open air passages to cool itself. Mechanical pumps need fans to cool them so outdoor use is not recommended. Then there are diaphragm pumps vs. peristaltic pumps. Diaphragm pumps pushes chemical through valves that open and close to force chemical into a pressurized water line. The peristaltic pumps push chemical through a tube that is being squeezed by rollers.