what is A rotary pump
A rotary pump comprising a housing defining an annular chamber with inlet and outlet ports spaced apart around the chamber, a flexible annular diaphragm forming one side of the chamber spaced opposite an annular wall of the housing , the diaphragm being sealed at its edges to the housing , a partition extending across the chamber from a location between the inlet and outlet ports to the diaphragm . The diaphragm is configured to be pressed progressively against the opposite wall of the housing to force fluid drawn in at the inlet port on one side of the partition around the chamber and to expel it at the outlet port at the other side of the partition .
