Types of check valves

A check valve refers to a valve used to prevent the backflow of media, also known as a one-way valve. The main types include rotary check valves, lift check valves, butterfly check valves, ball check valves, etc. It is widely used in fluid pipelines of industrial and mining enterprises.

The valve disc of the rotary check valve is disc-shaped and rotates around the axis of the valve seat channel. Due to the streamlined flow path inside the valve, the flow resistance is smaller than that of the lift check valve, making it suitable for large-diameter applications with low flow rates and little flow variation. However, it is not suitable for pulsating flow and its sealing performance is inferior to that of the lift check valve. Swing check valves are divided into three types: single disc, double disc, and half disc. These three forms are mainly classified according to the valve diameter, in order to prevent the medium from stopping or flowing backwards and reduce hydraulic shock.

Lift check valve: a check valve in which the valve disc slides along the vertical centerline of the valve body. Lift check valves can only be installed on horizontal pipelines, and ball shaped valve discs can be used on high-pressure small-diameter check valves. The valve body shape of the lift check valve is the same as that of the globe valve (which can be used interchangeably with globe valves), so its fluid resistance coefficient is relatively high. Its structure is similar to that of a globe valve, with the same valve body and disc as the globe valve. The upper part of the valve disc and the lower part of the valve cover are processed with guide sleeves. The valve disc guide sleeve can freely rise and fall inside the valve disc guide sleeve. When the medium flows downstream, the valve disc opens by the thrust of the medium. When the medium stops flowing, the valve disc descends on the valve seat by self sagging, which prevents 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 a medium inlet and outlet channel direction that is the same as the valve seat channel direction, and its flow resistance is smaller than that of the straight through type.

Disc check valve: a check valve in which the valve disc rotates around the pin shaft inside the valve seat. The disc check valve has a simple structure and can only be installed on horizontal pipelines, resulting in poor sealing performance; Pipeline check valve: a valve in which the valve disc slides along the centerline of the valve body. Pipeline check valve is a newly emerged type of valve, which has a small volume, light weight, and good processing technology, and is one of the development directions of check valves. But the fluid resistance coefficient is slightly larger than that of a swing check valve; Compression type check valve: This type of valve is used as a boiler feedwater and steam shut-off valve, and it has the comprehensive function of a lift type check valve and a globe valve or angle valve. In addition, there are some check valves that are not suitable for pump outlet installation, such as bottom valves, spring-loaded, Y-shaped, etc.