Non Return Valve Suppliers China
Non Return Valve Suppliers China
refers to the opening and closing member for the circular valve and by its own weight and media pressure to produce action to block the backflow of the medium of a valve. Belong to the automatic valve category, also known as check valve, check valve, backflow valve or isolation valve. The valve movement is divided into lift and swing type. Lifting check valve and globe valve structure is similar, only the lack of driven valve valve stem. The medium flows in from the inlet side (lower side) and out from the outlet side (upper side). When the inlet pressure is greater than the sum of the weight of the valve flap and its flow resistance, the valve is opened. Conversely, the valve closes when the medium flows backwards. Swing check valve has an oblique and can rotate around the axis of the valve flap, the working principle is similar to the lift check valve. Check valve is often used as the bottom valve of the pumping device, can stop the backflow of water. Check valve and shut-off valve used in combination, can play a role in the safety of isolation. The disadvantages are high resistance and poor sealing when closed.
Working Principle
Check valves can also be used to provide recharge to auxiliary systems in which the pressure may rise above the system pressure. Check valves can be mainly divided into swing check valves (rotating according to the center of gravity) and lift check valves (moving along the axis).
The function of this type of valve is to allow the medium to flow in one direction only, and to prevent the flow in the opposite direction. Usually this valve is automatic work, in one direction of flow of fluid pressure, the valve flap open; fluid flow in the opposite direction, by the fluid pressure and the self-weight of the valve flap combined flap act on the valve seat, thus cutting off the flow.
Among the check valve belongs to this type of valve, it includes swing check valve and lift check valve. Swing check valves have a hinge mechanism and a door-like flap that rests freely on the inclined seat surface. To ensure that the flap reaches the right position on the seat surface every time, the flap is designed in the hinge mechanism so that the flap has sufficient swing space and true, full contact with the seat. The valve may be made entirely of metal, or may be inlaid with leather, rubber, or synthetic coverings, depending on the performance requirements. Swing-open check valves, in the fully open condition, are virtually unobstructed by fluid pressure, so the pressure drop through the valve is relatively small. Lift check valves have a valve flap that sits on the seat sealing surface on the valve body. This valve is like a globe valve except that the valve can be raised and lowered freely. The fluid pressure causes the valve to lift off the seat sealing surface and the media backflow causes the valve to fall back onto the seat and cut off the flow. Depending on the conditions of use, the flap can be of all-metal construction or in the form of a rubber gasket or rubber ring inlaid on the flap frame. Like globe valves, the passage of fluid through the lift check valve is narrow, so the pressure drop through the lift check valve is somewhat greater than that of swing check valves, and the flow rate of swing check valves is rarely restricted.
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