Application Automatic recirculation valves protect centrifugal pumps against overheating, excessive noise, instability and cavitation during low flow conditions. If the flow through the pump falls below a certain level the bypass system opens and the fluid will be recirculated providing the required minimum flow through the pump.

Operation The main flow positions the check valve at a certain point. The stem of the check valve transmits the motion via a lever to the bypass. The bypass system controls the bypass flow in a modulating way and reduces the pressure to bypass outlet level. The full minimum flow is bypassed when the check valve is seated. The bypass is fully closed when the check valve is in its upper position, thereby allowing full pump flow to the system.

Flow sensitive The checkvalve moves upwards with increasing main flow and downwards with decreasing flow. The checkvalve transmits this motion via a lever to the bypass system (Fig. 3 and 4).

Type TDM The TDM consists of the check valve section (Fig. 2) with bypass configuration type M (Fig. 4). The movement of the lever is transmitted via a piston to the multi-stages vortex plug. The minimum flow is thereby bypassed in a modulating way over several pressure reduction stages. Applicable for differential pressures from 300 psi up to 3200 psi. Standard with non-return function.