Abstract: A coupler and manifold assembly which makes it possible to turn the shaft and impellers of an absorption chiller circulating pump with an external drive means instead of a hermatically sealed drive means, comprising an interconnecting combination of a plurality of restrictive orifices, a plurality of solenoids, conduit, and a plurality of chambers to help provide a differential vacuum across a seal face of a double mechanical rotating seal, to substantially prevent the introduction of air into the vacuum of the essentially closed system of an absorption chiller, during operation and/or shut down of the absorption chiller.