PURPOSE: To prevent the overflow of a liquid from a cartridge tank, by providing a means for detecting the change of the flow of the liquid on the way of an oil supply hose and stopping a pump unit when the liquid level of the cartridge tank reaches a definite height.

CONSTITUTION: When the outlet part 15 of an adaptor 13 is pushed in the opening part 29' of a cap main body 29 to send an operation signal to the control part 11 of a pump unit 9, the kerosene in a polyethylene tank 8 enters a cartridge tank 14 through an oil supply hose 12. When the amount of the kerosene in the cartridge tank 14 increases and the oil level reaches the leading end of an air pipe 37, the opening part of the leading end of the air pipe 37 becomes a closed state and the air in the cartridge 14 can not be discharged to the atmosphere and the internal pressure of the cartridge tank 14 slightly rises to reduce the supply amount of kerosene to the cartridge tank 14. At this point of time, the paddle 47 of a flow rate sensor 45 goes away from a reed switch 46 and the contact of the reed switch 46 becomes 'open' to stop the operation of the pump unit 9.