| 摘要 |
<p>A water-hammerless check valve which is capable of preventing both water hammering and pressure increase at the time of stoppage of fluid feeding irrespective of the state. A check valve adapted to be opened when a fluid is fed, to cause the fluid to flow, and closed when the feeding of the fluid is stopped, to prevent the reverse flow, characterized in that a main valve unit and a bypass valve unit are provided in parallel with each other, the main valve unit including single-leaf main valve disc adapted to open/close a main valve seat opened diagonally between an inlet flow passage and an outlet flow passage, having a working force in the valve-closing direction at all times, having a small shape resistance and a small inertial resistance, and being substantially seated on a main valve seat at a point of time at which the fluid flowing in the discharging direction loses the inertial and stops, the bypass valve unit including a bypass valve disc adapted to open/close a bypass valve seat, which is opened between the inlet flow passage and outlet flow passage, by linear forward/backward movement thereof, being connected to a brake unit for braking the movement of the bypass valve disc, and gradually closing the bypass valve seat as it is braked by the brake unit after the fluid has started to flow reversely, whereby the water hammering and pressure increase, which are ascribed to the reverse flow of the fluid occurring when the feeding of the fluid is stopped, is prevented. The bypass valve unit may be provided with a regulating mechanism for controlling the degree of opening of the bypass valve member. The main valve unit may be provided with a valve closing force regulating mechanism adapted to apply a working force to the main valve disc in the valve-closing direction.</p> |
