The check valve can be divided into a lift check valve, […]
The check valve can be divided into a lift check valve, a swing check valve, a double flap butterfly check valve and an axial flow check valve according to the structure. The lift check valve can be divided into three types: straight flow passage, vertical structure and angular flow passage.
The swing check valve is divided into three types: single-lobed, double-lobed, and multi-lobed. The butterfly check valve is straight-through. In the connection form, it can be divided into four types: threaded connection, flanged connection, clamped connection and welded connection.
The poppet of the lift check valve is the same piston and is therefore also referred to as a "piston check valve." At the beginning of the flow, it is pushed by the upstream fluid, disengaging the valve seat and opening the flow channel; when the flow stops, the valve flap returns to the valve seat under gravity to cut off the flow. The valve flap of the ball check valve is spherical, and its principle is similar to that of a lift check valve.
The flap of the swing check valve rotates away from the valve seat to cause fluid to flow forward, and when the upstream flow stops, the flap returns to the valve seat to form a seal, thereby preventing reverse flow of fluid.
In the double-lobe butterfly check valve, the two half-valves connected by the intermediate pin shaft constitute a closing member, and when the upstream flow stops, the two valve flaps are swiftly closed like a butterfly when driven by the spring; At the beginning, the two flaps fold back like butterfly wings and the valve opens, which is also the origin of the "butterfly" name.