Nash Engineering`s AT2004, two-stage liquid vacuum pump maintains back pressure on turbine condensers and can also be used for high noncondensable loads. The AT2004 features one moving part and the Nash cone port design to ensure turbine thermal efficiency. Each stage of the AT2004 consists of a shaft-mounted cast rotor enclosed by rugged head and lobe casings. The shaft and rotors are supported by heavy-duty bearings mounted externally. Exhausted air and seal water is transferred between the two stages via an interstage manifold. Within this manifold is a robust nonreturn valve which maximizes evacuation performance and reduces power demand. This valve also enables automatic bypass of the second stage when not required during pull down.