Monoflo Monoflo first began manufacturing progressing cavity pumps in 1935 and our heritage is built on this world-renowned design. Monoflo's heritage is built on the progressing cavity pump principle: a single helix rotor that revolves eccentrically inside a double helix stator, creating a continuously forming cavity as it rotates. Monoflo was the first progressing cavity pump manufacturer to be certified to ISO 9001 and the first to be awarded the upgrade Quality Management System 9001:2000.