Series MRK & MRM -Schroedahl Automatic Recirculation Valve

Function: SCHROEDAHL Automatic Recirculation Valve Type MRM

• The check valve moves upwards with an increase in main flow and downwards with a decrease in flow.
• The movement of the check valve is transmitted directly via the lever to the bypass system.
• When the check valve is closed, the bypass is completely open and full bypass flow is allowed to the suction tank.
• With increasing main flow, the check valve is lifted off its seat and moves upwards.
• Only when the bypass is completely closed, full flow to the system is allowed.
• The valve is set in the factory in such a way that the specified minimum flow is reached when the check valve is seated (this means that the main flow is zero).

Function : SCHROEDAHL Automatic Recirculation Valve Type MRK

• The MRK valve system is compromised of a check valve and a special control and throttle device for the minimum flow recirculation system (bypass system).
• The general valve functioning is related to the process flow quantity (flow sensitive).
• The bypass system itself consists of a primary regulating device (multi-staged), which is controlled by the main check valve and also a secondary, extra-special multi-staged pressure regulator.
• The functioning of the complete bypass is therefore split into 2 parts. Both parts (primary and secondary part) have to work together to fulfill the required pressure drop function as declared in the data sheet.
• The secondary part is controlled via the outer-connected pressure piping on the bypass section

The SCHROEDAHL Automatic Recirculation Valve Type MRM & MRK protects high pressure centrifugal pumps against overheating and cavitation problems by automatically maintaining a minimum flow when the system flow is at low load condition. At lower process flows, the check valve activates the bypass trim parts via a lever system, so that the pump is protected with the correct minimum flow. When the process/system flow starts (increases), the main check valve lifts off its seat and starts to operate (modulate) the bypass recirculation flow that returns to the system tank. When the check valve identifies enough system flow, the bypass closes automatically (switch point). If the system flow decreases again, then the bypass also starts to recirculate automatically.

Features

• Automatic bypass operation
• Modulating functioning
• Low maintenance
• Easy to install
• Damping of system pulsations
• Self-operated
• Reduces plant investment and operational costs