Improvements are disclosed in a rotary, lobar, positive-displacement pump and in a rotary, centrifugal pump, whereby all product-contacting areas of the pumps can be effectively cleaned without disassembly, i.e., cleaned in place. Non-rotating seals seal the impellers and isolate the pump shafts from the product zone. Each seal has an elastomeric member molded integrally thereto. The seal is biased by the elastomeric member so as to be slidably pressed against an impeller. In the lobar pump, certain passageways can be selectively closed and opened, so as to adapt the pump for being used to pump a pumpable material when closed and for being cleaned by a cleaning solution flowing therethrough when opened. Valves may be alternatively provided for analogous purposes.