Pump or compressor unit

A pump or compressor module for undersea use comprising a housing having a pump or compressor unit received therein, said pump or compressor unit comprising:

• first and second impeller assemblies,
• means mounting said first and second impeller assemblies for rotation about a common axis, said first impeller assembly comprising first and second support members spaced apart along said common axis, wall means connecting together said first and second support members remotely from said common axis, and at least one annular array of impeller blades on each of said support members, said impeller blade arrays being located between said support members and said second impeller assembly comprising a third support member located axially between said first and second support members and at least one annular array of impeller blades on each side of said third support member, said impeller blades being adapted to move a fluid in a generally radial direction between said first and said third support member and in the opposed generally radial direction between said second and said third support members,
• driving means for driving said first and second impeller assemblies in opposed directions about said common axis, said driving means comprising first and second electric motors having respective drive shafts drivingly connected to said first and second impeller assemblies respectively,
• first and second motor casings having therein said first and second electric motors respectively, said motor casings being within said housing,
• a seal compartment in each of said motor casings,
• a drive shaft seal within each of said compartments,
• barrier fluid circulating means for circulating barrier fluid in each of said motor casings, said barrier fluid circulating means being adapted to supply said barrier fluid to each of said seal compartments at a higher pressure than to the rest of said motor casing,
• fluid inlet and fluid outlet means adapted respectively to guide fluid to and from said first and second impeller assemblies;
• and
• guide means carried externally by said housing for guiding said module to a loading location at a subsea station having fluid connection ports.