The 21-Series Pumps are compact and designed for a wide range of applications including liquid transfer, spraying, circulation, filtration and dispensing. The 21-series of diaphragm pumps are self-priming and can be run dry without harm. It provides up to 1.2 gallons per minute. This compact automatic demand water system pump has a built-in pressure switch, which automatically starts and stops the pump when faucet is opened and closed.