The 33-Series is our general-duty on-demand positive displacement pump. It provides reliable performance in high water flow, moderate pressure applications. This 3-chamber diaphragm pump provides up to 3.0 gallons per minute and is capable of self-priming up to 9 vertical feet, and can run dry without damage. This automatic demand water system pump has a built-in pressure switch, which automatically starts and stops when the faucet is opened and closed. They’re easy to install, service and winterize.