Check Valve is known as One way Valve or Non return Valve. It is a critical automatic valve widely used in industrial fluid piping systems. It operates without manual control relying solely on the dynamic force of flowing medium to open and close automatically serving the core purpose of preventing medium backflow.The following are the classification by structural type of it.

     Lift Check Valve

     The Lift Check Valve shares a similar design with the Globe Valve featuring matching valve body and disc configurations. A key component is the guide sleeve machined on the upper disc and lower bonnet allowing the disc to move smoothly vertically for precise alignment with the valve seat. A pressure relief hole positioned on either the lower disc guide sleeve or upper bonnet guide sleeve discharges trapped medium when the disc rises reducing opening resistance.

     Based on pipeline installation it has two types:

     Straight through Lift Check Valve: Installed on horizontal pipelines. When medium flow stops the disc settles on the  valve seat by its own weight to block backflow.

     Vertical Lift Check Valve: Inlet and outlet channels align with the valve seat direction minimizing flow resistance. It is ideal for vertical pipeline installations prioritizing space and flow efficiency.

     Swing Check Valve

     The Swing Check Valve features a disc shaped closing element that rotates around a shaft in the valve seat channel. Its streamlined internal flow path reduces resistance lower than the straight through Lift Check Valve making it suitable for large diameter applications. However its sealing performance is slightly inferior and it generates significant water hammer pressure during closure causing sealing surface wear and noise. It works best in low velocity stable flow environments and is not recommended for pulsating flow.

     It also has three variants by disc count:

     Single disc Type: Equipped with one valve seat channel and disc suitable for medium diameter applications balancing performance and cost effectiveness.

     Double disc Type: Features two valve seat channels and discs designed for large diameter pipelines with DN over 600mm. The dual disc design distributes closing force evenly enhancing sealing and reducing water hammer impact.

     Multi disc Type: Composed of multiple small diameter discs that close sequentially when flow stops or reverses mitigating hydraulic impact. Lightweight discs ensure smooth closing minimizing valve seat damage. Suitable for extra large diameter applications with DN over 600mm.

    Compression Check Valve

      The Compression Check Valve is specialized for boiler feed water and steam shut off integrating functions of a Lift Check Valve and Globe Valve or Angle Valve. The valve stem and disc are not directly connected enabling automatic non return and manual override. The handwheel is used for boiler pressure testing steam shutdown or emergency closure when a parallel boiler malfunctions. Increased back pressure closes the valve automatically and the handwheel then secures the disc tightly on the seat for leak proof sealing.

    Other Types of Check Valves

     Additional specialized Check Valves serve specific applications:

     Foot Valves: Installed at pump suction ports with a filter screen to prevent debris entry and maintain pump prime.

     Butterfly Check Valves: Compact and thin profile using a swinging disc for low resistance. Suitable for large diameter pipelines and space constrained areas.

     Ball Check Valves: Utilize a spherical ball to block backflow offering fast response and reliable sealing for low pressure low flow or viscous medium systems.

    Installation and Operational Notes

    To ensure optimal performance and safety:

    Straight through Lift Check Valves must be installed horizontally. Vertical Lift Check Valves Ball Check Valve 2 and Foot Valves require vertical installation with medium flowing from bottom to top.

    Swing Check Valves are typically mounted horizontally but can be installed vertically or inclined if flow direction and disc movement are unobstructed.

     Lift Check Valves are recommended for small diameter pipelines with DN 50mm or smaller for superior sealing. Swing Check Valves suit large diameter pipelines with DN larger than 50mm to minimize flow resistance.

     During installation align medium flow direction with the arrow on the valve body. Incorrect orientation renders the valve ineffective risking backflow and equipment damage. Ensure sufficient space around the valve for maintenance.