How many kinds of pump are there?

There are primarily two main types of pumps: positive displacement pumps and dynamic pumps. Positive displacement pumps move fluid by trapping a fixed amount and forcing it into the discharge pipe, while dynamic pumps, such as centrifugal pumps, use rotational energy to draw fluid in and increase its velocity. Within these categories, there are various subtypes, including gear pumps, diaphragm pumps, and screw pumps for positive displacement, and centrifugal and axial flow pumps for dynamic types. The choice of pump depends on the specific application and fluid characteristics.