The general function of valves is to allow the medium to flow in only one direction and to prevent the flow in the direction. Usually, the valve operates automatically, and the disc opens under the action of a fluid pressure flowing in one direction. When the fluid flows in the opposite direction, the disc acts on the seat by the fluid pressure and the self-coincidence disc of the disc, thus cutting off the flow.
Among them, non slam check valve belongs to this type of valve, which includes swing non slam check valve and lifts non slam check valve. The swing non-slam check valve has an intermediate hinge mechanism and a door-like disc rests freely on the inclined seat surface. In order to ensure that the disc can reach the proper position of the seat surface every time, the disc is designed in a hinge mechanism so that the disc has sufficient swing space and makes the disc truly and comprehensively contact with the seat. Valve discs can be made entirely of metal or can be metal inlaid with leather, rubber, or synthetic coverage, depending on the performance requirements. The swing-type non slam check valve has almost no hindrance to the fluid pressure when it is fully opened, so the pressure drop through the valve is relatively small. The lift non slam check valve disc seat is located on the seating face of the valve body. In addition to the valve, the disc can rise and fall freely, the rest of the valve is like a globe valve. The fluid pressure causes the disc to rise from the seating surface, and the medium reflux causes the disc to fall back to the seat and cut off the flow. According to service conditions, the disc can be all-metal structure, or it can be in the form of rubber pads or rubber rings embedded on the disc rack. Like globe valves, fluids are narrow through lifting non-slam check valves, so the pressure drop through lifting non-slam check valves is larger than that of swing non-slam check valves, and the flow of swing non-slam check valves is limited very little.
Disc smashing and medium backflow.
The reason for disc breakage is that the medium pressure before and after non-slam check valve is close to equilibrium and mutual "saw" state, the disc often beats with the seat, and the disc made of some brittle materials (such as cast iron, brass, etc.) is broken. The precaution is to use non slam check valve with the disc as tough material.
The sealing surface is damaged and the impurities are clamped in. Repairing the sealing surface and cleaning the impurities can prevent backflow.