PURPOSE: To facilitate the compression restoring operation of the operating part of the pump by a method wherein small diametral short cylindrical parts are provided at both ends of the operating part of the pump.

CONSTITUTION: Air in the liquid dividing vessel A is forcibly discharged by the pump B by operating the pump B with a hose, of which tip end is inserted deeply into a large vessel 17, then, the inside of the vessel A is evacuated and the liquid is sucked into the large vessel 17. Subsequently, when the pump B is reversed and is operated under a condition that the tip end of a suction and discharge hose 16 is inserted into a small tank, atmosphere is forced into the liquid dividing vessel A and the innner pressure thereof is increased, thereby pushing out the liquid therein from the hose and supplying it into the small tank.