To provide a negative pressure breaking valve which surely dissolves a negative pressure in piping even if the negative pressure in the piping is small and in which liquid in the piping is hard to flow out.
This negative pressure breaking valve is provided with a valve housing 10 having a valve chest VR and a valve element 20 contained in the valve chest VR, and in the valve housing 10, a liquid inlet 12, an air inlet 14 and a valve seat 15 are formed. The valve element 20 is constituted by assembling a valve guide 15 comprising a base, projection and a small projection to a valve seat 21 comprising a seat body part 22, an elastic deformation part 23 and a support part 24, and an air inflow hole 28a penetrating the base is formed at the small projection. The valve element 20 is supported by the valve housing 10 in the state separated from the valve seat 15 so as to divide the valve chest VR, and when the pressure in the piping becomes positive, the elastic deformation part 23 is elastically deformed so that the valve element 20 is brought into contact with the valve seat 15 so as to close the air inlet 14.
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OUCHI RYOJI
FUJIWARA KATSUHIRO
