Abstract: The pump apparatus comprises a pump, suction device and a pressure container. The suction device is constructed as a structural unit and can be inserted coaxially from above into the pressure container. The pump likewise is constructed as a structural unit which can be inserted from above with self-centering and self-sealing connections coaxially into a hollow compartment of the suction device and is connectable therewith. By means of threaded bolts which, upon lowering the suction device, piercingly extend through bores provided at a ring flange of the suction device, the inserted suction device can be connected with the pressure container. If the need exists this can be accomplished by remotely controlled manipulator expedients.