Air-Actuated Differential Check Valve for Positive Displacement Flow Meter Systems

Air-Actuated Differential Check Valve for Positive Displacement Flow Meter Systems

Accurate liquid measurement requires more than a reliable flow meter—it requires control over air and vapor intrusion. The K-XX Series Air-Actuated Differential Check Valves are specifically designed to prevent fluid from flowing whenever air or vapor is present, ensuring precise metering and protecting downstream processes.

These valves are normally closed, spring-loaded units installed at the outlet of a positive displacement meter. When the incoming fluid pressure exceeds the combined resistance of the spring and back pressure, the valve opens to allow liquid flow. Conversely, if back pressure plus spring force is higher than the fluid pressure, the valve remains closed. This automatic operation ensures that only liquid is measured, preventing errors caused by trapped air or vapor—especially critical during split-compartment testing in tank trucks or bulk transfer applications.

Globally, this type of valve is recognized under various names. In North America and Europe, it is often called a Differential Check Valve or Air-Actuated Meter Check. In the Middle East and Africa, engineers frequently refer to it as a Flow Lock Valve. In Southeast Asia and Latin America, it is sometimes described as a Meter Outlet Air-Guard Valve. No matter the term, the function remains the same: accurate, reliable liquid measurement without air or vapor interference.

Installation is straightforward but requires careful attention to orientation and pressure relief. The valve features a flow-direction indicator, and its outlet is commonly fitted with a 3” NPT connection to integrate seamlessly with the meter system. When paired with an air and vapor eliminator, the K-XX Series ensures that the system is free from air intrusion while maintaining continuous liquid flow.

Available in aluminum construction with square flanges, the K-XX Series covers multiple flow ranges to match different meter sizes: for example, the K-50-AL supports up to 550 LPM for M-40 (1.5”) and M-50 (2”) meters, while the K-80-AL supports up to 1150 LPM for M-80 (3”) and M-100 (4”) meters. Its robust design accommodates high-use industrial applications, including fuel terminals, bulk oil depots, chemical plants, and LPG or solvent distribution systems.

In summary, the K-XX Series Air-Actuated Differential Check Valves are not just auxiliary components—they are essential for maintaining measurement precision, preventing air-related errors, and safeguarding positive displacement meter performance. For operators seeking reliability, accuracy, and reduced operational risk, this series provides a proven solution that integrates seamlessly into modern metering systems worldwide.