The series RUVAC WA Roots vacuum pumps are provided with directly flange-mounted air-cooled standard three phase motors. The oiled radial sealing rings of the RUVAC WA for sealing the shaft against the atmosphere are made of FPM (FKM) (fluor polymer). Roots vacuum pumps of the series RUVAC WAU are provided with an additional integrated pressure equalization line and a differential pressure valve. Pumps from these series are supplied with a vertical pumping action as standard.