To speedily and securely discharge an air bubble formed in a liquid feed pipe, extending from a discharge port to a liquid injection place, to the atmosphere.
This liquid injection device includes an intermittent operation type pump 1 which has a suction port 4 connected to a liquid storage tank at its lower part and a discharge port 5 at its upper part and is equipped with a main piping part 11 which has its lower end connected to the discharge port 5 when liquid in the liquid storage tank is supplied to the liquid injection place below the discharge port from the discharge port 5 through the liquid feed pipe 9 and has a 1st on/off valve 20 on the upper end side, a branch pipe part 12 which branches from an intermediate part of the main piping part 11 and where the liquid feed pipe 9 is connected, and a 2nd on-off valve 30 which is provided to the branch pipe part 12 or liquid feed pipe 9. Then the 2nd on-off valve 30 is closed and the 1st on-off valve 20 is opened to place the pump 1 in operation, thereby discharging air bubbles B in the main piping part 11 to the atmosphere.
TANAKA MITSUMASA
YAMAZAKI TOSHIHIKO
ELNA CO LTD