Automatic recirculation valve
The SSV, a special automatic recirculation valve, automatically protects centrifugal pumps – especially boiler feed water pumps – against wear and damage, as can occur if the pump runs dry or during low-load operation. Typical damages are for example a temperature increase, which can lead to partial evaporation of the medium, or recirculation in the impeller. It can also lead to flow separation and cavitation in the pump. Similarly, increased vibration and mechanical stresses occur in the pump and cause damage. The SSV bypass control valve opens as soon as the process flow demand falls to the same level as the minimum flow required by the pump. In this way, the specified minimum continuous flow required by the pump is maintained, even if there is zero process flow demand.
The SSV is installed in the pump discharge line directly on or near the pump discharge port. Each SSV exactly matches the operating data of the pump. The SSV responds to the process flow demand and ensures that if the bypass control valve is in the fully open or partially open position that the sum of flow in the main direction and in bypass direction is always at minimum flow necessary for the pump. This regulation takes place automatically, without the need for an external energy supply, or any kind of measuring equipment.
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