| 摘要 |
PURPOSE:To economize cleaning solvent as well as to solve cause of contamination during a second valve opening period by providing a lower side cleaning solvent supply port on the outer wall of a lower side cleaning solvent channel, squeezing the wall of a lower side pipe part so as to be brought closer on the outer circumferential surface of a balancing piston, and forming a space for discharge on the lower edge of the lower side cleaning solvent channel. CONSTITUTION:In case that both upper/lower side valve bodies 35, 41 are closed, cleaning solvent is introduced to a lower side cleaning solvent channel 43 when the cleaning solvent is fed from a lower side cleaning solvent supply port 44, and discharged from a cleaning solvent discharging port 45 through a space 46 for discharge between the outer circumferential surface of a balancing piston 42 and the inner circumferential surface of a lower side pipe part 9. Therefore, solvent contact surface in the balancing piston 42 including parts which are in contact with outside air can be cleaned by cleanings carried out under an opening/closing condition of the upper/lower side valve bodies 35, 41, an opening condition of the upper side valve body 35 only, and an opening condition of the lower side valve body 41 only. |
