The differences among lift check valves, swing check valves and butterfly check valves

Check valves are classified by structure into lift check valves, swing check valves and butterfly check valves. Weiti Industry will explain the differences among these three types of check valves for you

Lift check valve: A check valve in which the valve disc slides along the vertical center line of the valve body. Lift check valves can only be installed on horizontal pipelines. For high-pressure small-diameter check valves, the valve disc can be a ball. The valve body shape of the lift check valve is the same as that of the stop valve (it can be used interchangeably with the stop valve), so its fluid resistance coefficient is relatively large. Its structure is similar to that of a stop valve, and the valve body and disc are the same as those of a stop valve. The upper part of the valve disc and the lower part of the valve cover are machined with guide sleeves. The guide sleeve of the valve disc can freely rise and fall within the guide sleeve of the valve cup. When the medium flows in the same direction, the valve disc opens by the thrust of the medium. When the medium stops flowing, the valve disc drops onto the valve seat by itself, playing a role in preventing the medium from flowing back. The direction of the medium inlet and outlet channels of the straight-through lift check valve is perpendicular to the direction of the valve seat channel. The vertical lift check valve has the same direction of the medium inlet and outlet channels as the valve seat channel, and its flow resistance is smaller than that of the straight-through type.

Swing check valve: The disc of a swing check valve is disc-shaped and rotates around the axis of the valve seat channel. Due to the streamlined internal channel of the valve, the flow resistance is smaller than that of a lift check valve. It is suitable for low flow rates and large-diameter applications with infrequent flow changes, but it is not suitable for pulsating flow, and its sealing performance is inferior to that of a lift check valve. Swing check valves are divided into three types: single-disc, double-disc and multi-disc. These three forms are mainly classified according to the valve diameter. The purpose is to reduce hydraulic shock when the medium stops flowing or flows back.

Butterfly check valve: The butterfly check valve has a similar structure to the butterfly valve. The main difference lies in that the butterfly valve, as a shut-off valve, must be driven by an external force, while the butterfly check valve is an automatic valve and does not require a driving mechanism. When the medium stops flowing or flows back, the butterfly plate rotates to the valve seat by its own weight and the effect of the backflowing medium. This type of check valve can be used on both horizontal and vertical pipes and is usually installed in a wafer manner. Under the action of fluid pressure, the two valve discs overcome the spring force and rotate around the pin shaft. The open state is somewhat like a ">" sign. Some straight pipe sections should be left at the inlet and outlet of the valve because the valve disc must have a certain amount of rotation space.