Yarway automatic recirculation control (ARC) valves. Source: EmersonAn automatic recirculation valve (ARV) diverts fluid flow from the discharge of a centrifugal pump through a bypass circuit to ensure a minimum flow rate is maintained. This is vital for all variable-flow centrifugal pumps. While the primary function of an ARV is to protect a centrifugal pump from cavitation, overheating and running dry, the valve also serves several other functions.

Operating principle

The ARV is a three-way valve that typically incorporates a spring-loaded check valve, a hollow spindle and a letdown unit. The outlet to a process stream remains fully open when the process stream demands fluid flow. As the outlet flow rate diminishes, the differential pressure across the spring-loaded check valve is reduced and the check valve begins to close. When this occurs the hollow spindle begins to open a pathway through a bypass circuit. When demand ceases the check valve is fully closed and the bypass circuit is fully open. The letdown unit, located in the valve port that feeds the bypass circuit, ensures that the outlet pressure is maintained at safe levels.

The additional functions of the ARV are that of a normal check valve as it is an effective backflow preventer and pulsation dampener. It also functions as a flow and pressure control valve, replacing the functions of a check valve, a control valve or bypass flow and feedback loop, as the preloaded spring of the check valve and the letdown unit are adjusted to maintain the predetermined flow rate through a variable flow centrifugal pump.

Yarway ARC pump protection valves

Yarway automatic recirculation control (ARC) valves are self-contained, low-maintenance valves designed to protect centrifugal pumps from thermal damage and premature failure. The ARC valve design has a proven track record of over 40 years. According to the manufacturer, these valves provide precise recirculation control, are suitable for virtually all fluids and are easy to install. They feature a multistage pressure letdown unit and an integral check valve for cavitation prevention, pulsation dampening and recirculation of fluid back to a variable flow centrifugal pump when flow rates dip below a preset threshold.