Abstract: A rotary disc pump for pumping fluid materials, comprises a housing having a front and a back wall forming a chamber with a generally coaxial inlet in the front wall and a generally tangential outlet, an impeller is mounted co-axially within the chamber and comprises a shaft mounted in the back wall of said housing and having an outer end extending from the housing and an inner end within the chamber, at least a first circular which is disc mounted on the inner end of the shaft, and at least a second disc which is mounted in axially spaced relation to the first disc and has an opening in the center thereof, arid a conical member which extends co-axially of the shaft from the first disc toward the second disc.