| 摘要 |
The present invention relates to a direct-action spring-loaded overflow valve which is intended for operating pumps at any flow rate and at values exceeding the respective resistance of the system. This overflow valve limits the pressure in a system where a liquid is discharged using a positive-displacement pump and flows throughout the system at various flow rates. The valve cage (1) includes a valve body (22) fitted with a valve head (14), wherein both cage and body are arranged so that the valve head exhibits a second effective diameter which is larger than a first effective diameter after it is lifted from a valve seat (3). With the increasing displacement of the valve body (22), the valve head (14) uncovers simultaneously an increasing passageway section. The valve body (22) is made of a single piece in the shape a piston (11) which is capable of sliding in the valve cage (1) and has a third effective diameter larger than the second one so that the liquid flowing through the valve cage (1) upon the opening of said valve will generate a pressure differential acting on said piston (11) against the action of the first spring (21). |
