Check valve with antifouling drainer

The utility model discloses a check valve with a sewage-proof drainer, which essentially consists of a main valve which consists of a valve body, a fixed sleeve, a longitudinal reinforcing plate, a first-grade sealing device, a second-grade sealing device and a connecting rod. The utility model is characterized in that the middle section at the bottom of the main valve is provided with a sewage-proof drainer by a connecting pipe; the sewage-proof drainer consists of a valve cover, a rubber septum piece, a valve flap, a valve body, a valve seat, a short pipe and a connecting pipe; an upper pressure chamber is formed between the valve cover and the rubber septum piece of the sewage-proof drainer; a lower pressure chamber is formed between the valve body and the rubber septum piece which is linked with the valve flap. The utility model has sound structure and smart concept, can automatically induce the internal leakage of the upper valve body, and start the drainage; the utility model is an external hanging type, does not occupy the space of flow path, and has small resistance and generalization value.