THE Automatic Valve Solution for Centrifugal Pump Protection

Automatic Recirculation Valve (ARV)

STL Power & Process Controls are an official Schroedahl Channel Partner. 

SCHROEDAHL is the largest supplier of Automatic Recirculation Valves (ARV) in the world. 

The SCHROEDAHL ARV provides an automatic solution to protect centrifugal pumps against overheating, instability, and cavitation under no, or low process volume conditions.  As soon as the flow rate of the process falls below a certain value, the bypass opens, delivering the minimum flow required for the pump.

The application itself is usually a closed loop system and consists of a suction and recirculation line from, and to the tank. Typically, the ARV is mounted directly on the pump discharge flange.  The ARV comprises of a check valve in the main line and a control device for the minimum flow recirculation (the bypass control system).  The general valve operation is related to the process flow volume; all SCHROEDAHL ARVs are flow sensitive. 

Compared to a Continuous or Controlled Bypass System that both need an additional check valve, the Schroedahl ARV is distinguished by: 

1. Flow sensing and modulating function
2. Check valve
3. Automatic bypass end connection
4. Pressure reduction of the bypass flow without cavitation

This results in the following advantages compared to conventional systems:

ü  A single self-operated unit which can be mounted directly on the pump outlet
ü  No external energy required – easy to install
ü  Reliable, direct operation with little hysteresis
ü  No special maintenance required – the unit is self-lubricating (pump fluid)

Figure A

The outlet main flow controls the check valve and positions it in proportion to the flow. The stem of the check valve transmits the motion via a lever to the bypass (Fig. A).  The bypass system regulates the bypass flow in a modulating way and reduces the pressure to the bypass outlet pressure level without cavitation.  The full minimum flow is bypassed when the main 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.

Please contact our Technical Manager, Ash Kalsi, to discuss the ARV in more detail or to request the full Engineering Letter. 

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