Abstract: The liquid/gas separator for soapy water consists of a fixed cylindrical housing defining a fixed chamber for supporting a rotating shaft supported about the longitudinal axis. A preswirl chamber communicating with the main chamber in which are disposed parallelly spaced annular coalescing disks supported to the rotating shaft, serves, with the preswirl chamber, to rotate the centrifuged water to form a water ring adjacent the outer wall of the chamber and flows the gas through a central passage formed in the shaft along the longitudinal axis to be vented in response to a control valve located at the open end of the shaft remote from the preswirl chamber. Control means responsive to the differential of the static pressure of the water ring and the gas pressure, control the venting of the gas.