PURPOSE: To simplify a system to make the title device light and small by making it possible to suck liquid also from the intermediate stage of a multi- stage compression type liquid sealed pump portion, directly coupling a Pitot pump portion to the liquid sealed pump portion by a same drive shaft, and connecting the Pitot pump portion to the outlet of the liquid sealed pump.

CONSTITUTION: Liquid sealed pumps W1, W2 are provided with casings 1, 11 and impellers 2, 12, liquid is sucked from suction pumps 5, 8 to be compressed in capacity sealed by sealed liquid 3, 13 and is supplied under pressure from a discharge port 15 via a communicating passage 16 to a Pitot pump portion P. The liquid is separated to gas and liquid by an impeller 19 in a casing 17. The liquid sealed pumps W1, W2 (liquid sealed portion W) and the Pitot pump portion P are directly coupled with each other by a same drive shaft 10. Thus, the system is pimplified, the weight thereof is lightened and the size thereof is smallened for using two phases fluid of gas and liquid pressure areas of which differs from each other.